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SERVICE MANUAL

1. I S SM 2020 Disc Storage Unit CABLE ASSEMBLY FROM ACTUATOR Chassis Assembly 73080 Bottom View Figure 4 9 4 19 SM 2020 Parts List for Chassis Assembly Partial figure 4 10 Reference No 1 19200 2 73033 3 13333 4 73700 5 22580 6 15845 7 18501 8 13314 9 13366 10 73081 11 73420 12 13351 13 13349 14 14025 15 0576 16 13384 17 14006 18 73079 19 73402 20 18590 21 18510 22 14026 23 13838 24 13453 25 73401 26 73091 73092 27 18511 28 14122 29 14004 30 13353 31 24330 32 74413 33 73333 34 14105 35 19104 36 73417 37 18550 38 18543 39 73242 40 18970 41 73418 73419 4 20 Part Number Part Name Dowel Pin Drive base Screw Power supply circuit card Capacitor Clamp Standoff Screw Screw Base chassis Transformer Screw Screw Washer lock Spring Screw Washer Spring post Bracket post assembly Relay spin motor start Bushing Washer Screw set Screw Spin motor assembly Pulley spin motor 1500 60Hz Pulley spin motor 1500 50Hz Snap bushing Nut Washer Screw Circuit breaker Bracket Insulator Nut Washer shoulder Capacitor assembly Capacitor 15V Capacitor 5V Spin motor Relay power off delay Switch fuse assembly 115V 60Hz Switch fuse assembly 220V 50Hz Disc Storage Unit Quantity N N N F E R N N N E E E E HI N Ii I GA IRN 00 f I IE gt SM 2020 Disc S
2. j l U SERVO TIMING U24 6 gt 7 ERE ny Ier OE pug s 1 gt COUNT PULSE f 1 A B D f L f DIFF 0 FWD DRIVE LINEAR ZONE ENABLE REVERSE A B J 1 1 I i FOWARD A B J 1 1 1 t 1 1 REV U U U U24 12 ARRIVAL ZONE A B T Ll f l f l f 1 1 A B D ee P ee i eme I l f 1 1 1 11 REVERSE A B il 1 t 1 1 1 l 1 upi 1 25 MILS FWD 024 8 1 94 MILS rev U U U 2 5 MILS 0 69 MIL A B l 0 56 MIL i 5 0 MILS TRACK CENTER gt gt ARRIVAL LINER TRACK 0 i 1 I I l f 1 1 l 1 LI LJ 1 1 REVERSE A B Jord 4 oT Oe Tn U22 12 REV u U U 3 60 Disc Storage Unit OPTICAL SIGNAL PROCESSING TIMING HOME POSITION TRACK ZERO oA B A B A B LINEAR SIG A B LOGIC A B LOGIC Figure 3 36 OHO LOGIC MECHANIZATION COUNT DIRECTION LATCH A B A B D FWD DRIVE SET CYLINDER REV DRIVE A B D Track Number and Head Position Comparison Circuits Sheet 1 Disc Storage Unit DMA DISC
3. HEADS OVER DISC SURFACE YES PUSH CARRIAGE AGAINST REAR CH T ES 2 CRASH STOP CARTRIDGE LOCK CHECK HEADS PER PREVENTIVE OBSERVE MAINT PROCEDURE CARRIAGE MOTION Disc Storage Unit DRIVE READY X YES LIT 9 VERIFY HIGH 70 SPIN SPEED AT A5 6 i YES VERIFY HIGH POWER OFF SIG AT B5 1 NO REPLACE REPAIR DRIVE CONTROL LOGIC BOARD YES REPLACE REPAIR POWER SUPPLY CHECK RECEIVER INTERLOCK SWITCH CHECK POWER TRANSFORMER CARRIAGE MOVES VERIFY THAT DRIVE READY READY LIGHTS WITHIN 90 SECONDS FROM CARTRIDGE LOCK Figure 3 43 YES REPLACE FIXED DISC YES REPLACE HEAD FIXED DISC DAMAGED Troubleshooting Flow Diagram REPLACE INTERFACE CIRCUIT CARD Sheet 1 NO YES CHECK SECTOR TRANSDUCER OUTPUT AT A5 5 YES NOTCHES DETECTED REPLACE SECTOR TRANSDUCER Disc Storage Unit TWO TRACK SEEK LOOP PROGRAM ENTER FROM KEYBOARD NEW 10 DIM A 110 20 GET 0 0 30 FOR A 0 TO 50 40 NEXT A 50 GET 0 300 A 60 IF A 50 GOTO 80 70 GOTO 20 80 END RUN NOTE STEP 50 CHANGE 300 TO TX96 TO SEEK DIFFERENT TRACK TRACK STEP PROGRAM ENTER FROM KEYBOARD NEW 10 DIM A 110 20 FOR S 0 TO 19200 STEP 96 30 IF 5 19200 GOTO 60 40 GET 0 5 50 NEXT S 60 END NOTE CHECK DIFF1 AT A3 7 FOR LOW PULSES THEN ENTER 20 FOR S 0 TO 19200 STEP 192 RUN
4. 15V 15V POWER ON LAMP R27 1 15V 5V GND i R2 5V GND R3 5V 0 POWER SUPPLY DRIVE CONTROL LOGIC MTR SW ON HI B5 R W SAFE 2 HI PL BS MTR SW ON FIG 3 35 POWER SAFE 5 FIG 3 35 FIG 3 39 FIG 3 37 OTOR 15V UNREG TO DRIVE HOME AMP SPIN 15 VOLT ELAY MOTOR SUPPLY FIG 3 37 BRIDGE RECTIFIER TO REVERSE AMP FIG 3 37 15 VOLT REGULATOR 15 VOLT REGULATOR LINE POWER FILTER TRANSFORMER TO FORWARD AMP FIG 3 37 15V DISABLE 45V 5 VOLT REGULATOR 15V RAM 15V 5 VOLT SUPPLY BRIDGE RECTIFIER DELAY RELAY DRIVER SERVO 5V 5V POWER ON LAMP FRONT PANEL AND UNLOCK SOLENOID POSITION TRANSDUCER FIXED DISC TRANSDUCER REM DISC TRANSDUCER 5V 15V 15V 15V 5V 15V 5V 15V 15V 5V 15V 15V 5V 15V SM 2020 READ WRITE SERVO NO 2 NONE N AS DIODE REG 22 N Figure 3 34 Power Function 3 57 SET TO APPLY AC POWER TO TRANSFORMER 15V SUPPLIES ENERGIZED LIGHT MAIT WAIT MOTOR SWITCH SET TO CARTRIDGE UNLOCK LIGHT SUPPLY MOTOR SWITCH ON AND SPIN STOPPED SIGNALS ACTIVE ENABLE 5V SUPPLY REMOVABLE CARTRIDGE IN PLACE YES APPLY 115V TO SPIN MOTOR
5. JL J NY WAIT ENERGIZE DOOR UNLOCK SOLENOID LIGHT CARTRIDGE UNLOCK DISABLE 5V SUPPLY E MAKE LOAD HEADS ACTIVE HIGH MAKE DRIVE FORWARD TO ZERO LOW AND SUBSTITUTE FOR BIT 16 OF CYLINDER REGISTER CONTINUE FORWARD DRIVE TO ACTUATOR TRACK 000 DETECTED RESET INITIALIZE LATCH MAKING DRIVE FORWARD TO ZERO HIGH REPEAT CONTINUE NORMAL SERVO ARTHIMETIC LOGIC AND SERVO LOOP CONTROL ACTUATOR YES TRIGGER ARRIVAL DELAY ONE SHOT WAIT 6 121 ELASPED ARRIVAL STILL ACTIVE YES SET ARRIVAL FLIP FLOP WAIT 1 AND R W SAFE 2 ACTIVE GENERATE DRIVE READY LIGHT DRIVE READY GENERATE ACCESS READY DRIVE CONTROL TRANSFERRED TO CONTROLLER DR HOME OP HOME POS HOME POS DLYD ARRIVAL HDS LOADED DR FWD TO TRACK INITIALIZATION OP DRIVE SELECT ADDRESS BUS SET CYLINDER CYLINDER ADDRESS REGISTER DRIVE SELECT WRITE GATE CONTROLLER TO DRIVE ERASE GATE CONTROLLER TO DRIVE DRIVE SELECT READ GATE SELECT HEAD SECTOR PULSE SM 2020 FLOW AND TIMING DIAGRAMS Sese a 20046 JE L C Ee L TYPICAL INITIALIZATION TIMING REMAIN ACTIVE 200 NS MINIMUM NS fe PREVIOUS ADDRESS 500 NS L MAXIMUM NEW ADDRESS NEW ADDRESS TRACK GN 304s F 25 us MINIMUM
6. SELECT WRITE GATE ONLY ONE HEAD SELECTED WRITE GATE p SELECT ERASE GATE SEEK INCOMPLETE ARRIVAL E F PONER SAFE INTERFACE SELECT ERASE GATE TP14 SELECT WRITE GATE SM 2020 LOGIC READ WRITE SELECT HEAD 0 HEAD 0 SELECTED SELECT HEAD 1 E HEAD 1 SELECTED tap MULTIPLE SELECTION Im SELECTION TO FIG 3 31 DECODER SELECT HEAD 2 T HEAD 2 SELECTED ELECTIO SELECT HEAD 3 HEAD 3 SELECTED Pen HEAD SELECTION CIRCUITS HEAD 1 Y WRITE DATA ADD WRITE i CURRENT FIG 3 36 BIT 256 WRITE CURRENT GENERATOR SELECT WRITE GAT ONLY ONE HEAD SELECTED SELECT ERASE GATE SEEK INCOMPLETE ARRIVAL F F FIG 3 34 POER SAFE INTERFACE ERASE SELECT CURRENT GENERATOR F ERASE GATE TP14 SELECT WRITE GATE Figure 3 39 Write Function Sheet 2 3 67 SM 2020 Disc Storage Unit READ FLOW DIAGRAM CONTROLLER SELECTS DRIVE REPEAT CONTROLLER COMMANDS NEW TRACK NUMBER READ DEMODULATOR TIMING DATA PERIOD 640 nS RECORDED DATA 0 2F CLOCK J J J DOUBLE FREQUENCY WRITE DATA J RD GATE TRIGGER f 50 nS RAW DATA 1F CLOCK 0 RAW DATA CLOCK LOLI LJ osc MAMA DATA READ DATA LATCH READ CLOCK J J l CONTROLLER SELECTS READ WRITE HEA
7. decre gh oA ES 4 22 4 12 Transformer Assembly 73420 xo tn BE Je ane NIS ee Sy tede S d 4 23 4 13 Prefilter Assembly 73130 4 24 4 14 Covers Package 75240 os Given VET Ge wo 1825 4 15 Switch Panel Assembly 73250 DECEM ELE DECEDERE E DT 4 26 4 16 Sector Transducer Assembly 73606 4 27 4 17 Bottom Panel 73080 4 28 4 18 Drive Control Logic NE re date wore SS E 4 30 4 19 Interface 73540 ces tat etek Seter Pra EG VE 4 32 4 20 Servo Card No 1 73590 xx xc 4 34 4 21 Servo Card No 2 ed 5 ohn 73 4 36 4 22 VFO 73560 gg Wax 4 38 4 23 Read Write 73460 PE 2074 ae wis BE AGA Je 4 41 4 24 Power Supply 73700 Aw Segoe oue 4 25 Terminator Assembly 73710 TE Mes w 4 45 vi Disc Storage Unit SM 2020 Section 1 GENERAL DESCRIPTION 1 1 SCOPE This manual contains the general description operation and maintenance data for the Models 2115 100 2215 100 2215 200 and 2315 200 Disc Storage Units manufactured by Basic Four Corporation 18552 MacArthur Boulevard Santa Ana California 92707 The Disc Storage Unit is an integral part of the BASIC FOUR data processing systems Control of th
8. LOAD CYL REG CYL BIT 128 TP6 E CYL BIT 256 INITIALIZATION OP ADDERS EXCLUSIVE OR FUNCTION 128 DRIVE DIFF pub 256 COUNT PULSES PRESENT CYLINDER FORWARD ADDRESS s DR HOME OP COUNTER DRIVE FORWARD COUNT DOWN FIG 3 37 COUNT UP CYL ADDERS CARRY CARRY BORROW LATCH CYL ADDERS BORROW FIG 3 35 INITIALIZATION OP SM 2020 SERVO NUMBER TWO DIFF 1 DIFF 0 FIG 3 37 SHAPED D A ERROR CONVERTER FIG 3 37 DIFF 32 DIFF 64 256 DIFF 128 256 Figure 3 36 Track Number and Head Position Comparison Circuits Sheet 2 3 61 DRIVE CONTROL LOGIC SHUTTER ASSEMBLY RVDR REVERSE DRIVE ARZN ARRIVAL ZONE TRKO TRACK 000 MMPS HOME POSITION LZEN LINEAR ZONE ENABLE FDEN FORWARD ENABLE RYEN REVERSE ENABLE FDDR FORWARD DRIVE SERVO NUMBER ONE TP6 oA B CURRENT SUPPLY REFERENCE RECTIFIER AND FILTER LOGIC BUFFER INVERTER LOGIC BUFFER NULL DETECTOR LOGIC BUFFER TACH GEN M SM 2020 DRIVE 186 CONTROL i LOGIC LED DRIVE FIG 3 36 50 re MB L0 A B AtB A B A B HI BEFORE A B HI COUNT DOWN PULSES RVEN LO HI BEFORE A B HI COUNT UP PULSES FIG 3 36 FIG 3 36 LIN SIG TP COUNT PULSES 5 3 36 A B LZEN DIFF 0 FDDR D
9. 7 51 ohm 55 1 4w R34 R43 R14 R47 R48 R52 R5 10845 Resistor RN55D 162 ohm 15 1 8w R7 R49 R54 R55 10841 Resistor RN55D 147 ohm 1 1 8w R12 R63 R64 R65 10049 Resistor RC07 1K 5 1 4w R13 R37 R41 10034 Resistor RC07 240 ohm 5 1 4w R14 10071 Resistor RC07 8 2K 5 1 4w R17 10052 Resistor RC07 1 3K 5 1 4w R19 11117 Resistor RN55D 82 5 ohm 15 1 8w R20 10937 Resistor RN55D 237 ohm 1 1 8w R21 11105 Resistor RN55D 61 9 ohm 11 1 8w R22 11363 Resistor RN60D 1 40K 1 1 4w R23 10427 Resistor RC32 120 ohm 5 1 R24 10032 Resistor RC07 200 ohm 5 1 4w R28 R29 R51 10039 Resistor RC07 390 ohm 5 1 4w R30 R32 13204 Potentiometer 100 ohm 3 4w R31 10839 Resistor RN55D 140 ohm 1 1 8w R33 10925 Resistor RN55D 178 ohm 15 1 8w R35 R36 10861 Resistor RNS5D 1 33K 1 1 8w R38 10035 Resistor RC07 270 ohm 5 1 4w R39 R40 10026 Resistor RC07 110 ohm 5 1 4w R42 10825 Resistor RN55D 100 ohm 1 1 8w R45 10045 Resistor RC07 680 ohm 5 1 4w R46 10864 Resistor RN5SD 1 43K 1 1 8w R50 11025 Resistor RN55D 332 ohm 1 1 8w R55 10056 Resistor RC07 2K 5 1 4w R56 R61 10966 Resistor RN55D 2 67 1 1 8w R57 10010 Resistor RC07 24 ohm 5 1 4w R58 R59 11027 Resistor RN55D 332 ohm 1 1 8w R60 11159 Resistor RN55D 7 15K 1 1 8w R62 10102 Resistor RCO7 11K 5 1 4w SM 2020 Quantity Ref Ref HNO RR RPP ePN en
10. ADJUSTING SCREWS Figure 3 7 Filter Mounting Screw Location b Replace absolute filter with P N 73663 3 20 Disc Storage Unit SM 2020 Table 3 2 Twelve Month Preventive Maintenance continued c Reassemble absolute filter assembly in the reverse order of removal NOTE Tighten the nine screws mounting the air filter such that the foam tape between the air filter and the chassis is evenly compressed Perform steps 21 through 31 of six month preventive maintenance 3 13 CLEANING SHUTTER AND REMOVABLE DISCS Some malfunctions may be caused by a dirty shutter or by an accumulation of foreign particles on the surface of removable discs The following paragraphs detail the accepted method for cleaning these items 3 13 1 SHUTTER CLEANING PROCEDURE 1 Remove glass shutter from shutter assembly NOTE The glass shutter should only be cleaned when removed from drive 2 Prepare a few pieces of lens paper lightly dampened do not soak with 91 Isopropyl Alcohol 3 Holding the shutter on the edge gently wipe the shutter surface until all foreign material is removed 4 Repeat steps 2 and 3 if necessary 3 13 2 REMOVABLE DISC CLEANING PROCEDURE 1 Prepare a cleaning paddle by wrapping several layers of tissue around tongue blade 2 Lift and rotate disc from the bottom of opened cartridge while wiping surface lightly with dampened paddle 3 14 OPTICAL TRANSDUCER AND SHUTTER ALIGNMENT The opti
11. YES CHECK REPLACE CONTROLLER DRIVE CONTROL AND CABLE LOGIC CARD READ WRITE CONNECTORS CARD REPLACE VFO CARD SM 2020 REPLACE READ MRITE CARD RUN DISC DIAGNOSTIC AGAIN ERROR PERSISTS YES n REPLACE VFO CARD SET TO CARTRIDGE UNLOCK REMOVE CARTRIDGE REPLACE COVERS AND SECURE DRIVE Figure 3 43 Troubleshooting Flow Diagram Sheet 2 3 73 Disc Storage Unit SM 2020 Section 4 PARTS LISTS 4 1 SCOPE This section contains illustrated parts breakdowns and complete piece parts listings The first part of this section includes exploded view illustrations of the drive mechanical components The second part of this section contains assembly drawings of circuit cards and parts lists organized by reference designator symbol numbers 4 2 PART NUMBERS OF DISC STORAGE UNITS Model Packing Operating Part Number Density Power Number 2115 2 100 000 115V 60Hz 400180 2115 2 100 000 220V 50Hz 400181 2215 4 200 000 115V 60Hz 400170 2215 4 200 000 220V 50Hz 400171 2315 8 400 000 115V 60Hz 400173 2315 8 400 000 220V 50Hz 400174 SM 2020 Parts List for Disc Drive Assembly figure 4 1 Reference No WANA Q Part Number 73170 73184 19160 13372 73180 73540 73590 73480 73460 73560 73720 73401 19140 73281 25500 73160 73193 13349 Part Name Receiver assembly Anchor Spring Screw Cover assembly fixed disc Interface circuit card Se
12. dimensions Height 8 72 inches Width 19 0 inches Depth 24 75 inches Weight 65 pounds 1 6 Disc Storage Unit Name Switch Panel Spin Motor Assembly Actuator Assembly Optical Positioning Transducer Assembly Drive Control Logic A0 Interface AS Servo No 1 A4 SM 2020 Table 1 3 Component Description Part Number Description The switch panel located on the front of the bezel mounts two rocker switches and three indicators The function of each is described in Section 2 74210 The spin motor drives the blower for the air filtration circulation system and the spindle supporting the discs by a single continuous belt The spin motor assembly consists of a 50 60 Hz ac motor and an attached pulley and is attached to a self adjusting spring loaded bracket mounted to the bottom of the drive chassis 73401 The actuator assembly moves the carriage assembly which 73020 supports the read write heads and shutter assembly The actuator is a rotary motor The shutter is a glass mask that passes between a LED light source and photo electric cell of the optical transducer assembly The optical positioning transducer assembly detects 73010 carriage position velocity direction and carriage home position This assembly consists of a LED and mask mounted on a block and separated from a PC board upon which is mounted three photo diodes and three operational amplifiers Th
13. 20 21 C8 C12 C17 CR3 CRS CR4 R1 R11 R12 R19 R2 R13 R3 R22 R4 R23 R5 R6 R7 R15 R16 R17 R24 R8 R9 R20 R10 R21 R14 R18 01 U2 U3 U4 U6 U7 U13 05 09 U8 U10 U11 U12 U14 U15 U16 Part No 74510 12509 22540 12641 12723 12812 12521 1206 12515 13005 13009 10063 10105 13212 11068 10990 10112 11166 10069 10101 10975 10045 60573 17055 17001 17021 18000 17024 17013 17002 17042 Part Name Interface Assembly Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Diode 1N3 Diode 1N5 Resistor Resistor Potent iome Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Integrated Integrated Integrated Integrated Integrated Integrated Integrated Integrated Integrated 192P 0 01uf 10 80V 0 1uf 2 80V DM15 500pf 5 SOOV 150D 22uf 20 20V CER 0 1uf 20 50V 192P O 1uf 210 80V 150D 220uf 20 10V 192P 0 0334f 105 80V 064 231B 5 1V 5 RC07 3 9K 5 1 4w RCO7 15K 5 1 4w ter SOK 3 4w RN55D 4 99K 1 1 8w RN55D 26 7K 1 1 8w RC07 30K 455 1 4w RN55D 8 45K 41 1 4w RCO7 6 8K 5 1 4w RCO7 10K RN55D 18 07 680 5 1 4w 7K 1 1 8w ohm 5 1 4w 75107N 9602 7404 7405 resistor pac 1 5K 7438 7476 7400 7408 Circuit Circuit Circuit Circuit Circuit Circuit Circuit Circuit Circu
14. Figure 3 2 Head Spacers Inserted Between Heads Using dental mirror check read write heads for evidence of oxide build up If oxide build up is present check disc surfaces for evidence of contamination If contamination exists clean discs Clean read write heads a b Prepare a cleaning paddle by wrapping several layers of tissue around tongue blade Lightly dampen paddle in alcohol do not soak Never touch heads with fingers Using a second unwrapped tongue blade to support the back of each head swab head surfaces with lightly dampened paddle Prepare a new paddle repeat step c until cleaning tissue shows no signs of having removed head surface residue Using dental mirror inspect head surface If still dirty repeat cleaning steps 3 15 SM 2020 Disc Storage Unit Table 3 1 Six Month Preventive Maintenance continued 13 Move the carriage assembly back and forth and clean both the top and bottom carriage rails using a lint free tissue dampened with 91 Isopropyl Alcohol CAUTION Ensure that head spacers are installed between both removable disc and fixed disc heads 14 Use a cotton swab dampened with molycoat G to lubricate the long and short actuator rails while moving the carriage assembly back and forth See figure 3 3 SHORT RAIL LONG RAIL Figure 3 3 Lubrication Locations 15 Holding the carriage assembly against the rear crash stop and remove head spacers from between the remov
15. HE 5 4 1 Part Numbers Of Disc Storage Units EE EEE 4 1 Parts List for Disc Drive Assembly 4 2 Parts List for Receiver Assembly 2 1 4 4 Parts List for Fixed Disc Cover Assembly Right Side 4 6 Parts List for Fixed Disc Cover Assembly Left Side 4 8 Parts List for Door Assembly DE e 1 Parts List for Chassis Assembly 1 Parts List for Actuator Assembly Top View 1 Parts List for Actuator Motor Assembly Parts List for Chassis Assembly Bottom View Parts List for Chassis Assembly Partial Parts List for Blower Assembly Parts List for Transformer Assembly r Parts List for Prefilter Assembly Parts List for Covers eu el eas Parts List for Switch Panel Assembly Parts List for Sector Transducer Assembly Parts List for Bottom Panel uk Parts List for Drive Control Logic Cireuit Card PE Parts List for Interface Circuit Card Parts List for Servo Circuit Card No 1 Parts List for Servo Circuit Card No 2 Parts List for VFO Circuit Card Parts List for Read Write Circuit Card Parts List for Power Supply Circuit Board Parts List for Terminator Assembly PO SDN N N N ND D BP O 1 Ca 1 amp Q1 tS 09 r 1 Disc Storage Unit SM 2020 LIST OF TABLES 5 5 m 1 1 Storage Capacity of Disc Storage Units 1 2 1 2 SPECLEIC
16. a With receiver handle in the up position remove two springs holding receiver assembly figure 3 31 TO BE SUPPLIED Figure 3 31 Fixed Disc Removal Receiver Cover b Lift up receiver assembly to gain access to four screws figure 3 32 MOUNTING SCREW 1 OF 4 Figure 3 32 Fixed Disc Removal Fixed Disc Cover 3 52 Disc Storage Unit SM 2020 Loosen two screws holding one of the receiver brackets slide bracket away from receiver until the flange bearing comes out Then remove receiver cover After identifying wire destination remove the blue and violet leads from the solenoid After identifying wire destination remove both red leads from the microswitch Remove latch linkage from fixed disc cover assembly figure 3 31 Disconnect B7 connector from the drive control logic circuit card figure 3 25 Remove four screws securing fixed disc cover to drive chassis and remove fixed disc cover figure 3 32 NOTE Four spacers are located under the fixed disc cover assembly Extend drive over the work bench such that the disc spindle is accessible from the bottom Using 5 32 inch allen wrench remove three screws securing the disc spindle assembly to the chassis figure 3 33 Push fixed disc and disc spindle as a unit out through the top of the chassis TO BE SUPPLIED Figure 3 33 Fixed Disc Removal Disc Spindle Moun
17. NOTE CHECK DIFF2 AT A3 8 FOR LOW PULSES THEN ENTER 20 FOR S 0 TO 19200 STEP 384 RUN NOTE CHECK DIFF4 AT A3 9 FOR LOW PULSES THEN ENTER 20 FOR S 0 TO 19200 STEP 768 RUN NOTE CHECK DIFF8 AT A3 10 FOR LOW PULSES THEN ENTER 20 FOR S 0 TO 19200 STEP 1536 RUN NOTE CHECK DIFF16 AT A3 11 FOR LOW PULSES THEN ENTER 20 FOR S 0 TO 19200 STEP 3072 RUN NOTE CHECK DIFF32 AT A3 12 FOR LOW PULSES THEN ENTER 20 FOR S 0 TO 19200 STEP 6144 RUN NOTE CHECK DIFF64 256 AT A3 13 FOR LOW PULSES THEN ENTER 20 FOR S 0 TO 19200 STEP 12288 RUN NOTE CHECK FOR LOW PULSE DIFF128 256 AT A3 13 HEADS POSITIONED OVER DISC 2 SET TO CHECK ACTUATOR RAILS FOR CLEANLINESS RAILS DIRTY OR YES OBSTRUCTED NO ENTER TWO TRACK SEEK LOOP PROGRAM CHECK AMPLITUDE AND PHASE OF 9A AND B PER TABLE 3 3 AMPLITUDE ACCEPTABLE YES VERIFY THAT HMTP A4 S SWINGS TO 2V AT TRACK 000 ENTER TRACK STEP PROGRAM WATCH CARRIAGE MOTION CHECK DIFF PULSES CARRIAGE MOVES PER PROGRAM YES NO OIFF PULSES PER PROGRAM REPLACE SERVO 2 CIRCUIT CARD PUSH CARRIAGE AGAINST REAR CRASH STOP CLEAN LUBRICATE RAILS PER PREV MAINT ALIGN OPTICAL TRANSDUCER PERFORM OPTICAL TRANS DUCER SHUTTER ALIGNMENT REPLACE DRIVE CONTROL LOGIC CIRCUIT CARD AS SOON AS SWITCH IS TH
18. PANEL POWER SWITCH AND SECURE POWER CORDS ARE BACK PANEL LINE FUSES 600D 2 CARTRIDGE UNLOCK LAMP 6000 YES YES REPLACE REMOVE DRIVE REMOVE TOP BAD FUSE TOP COVER COVER IS CONTROL 0 TO iV AT LOGIC B3 1 REPLACE NO LAMP ISOLATE YES OPEN YES ISOLATE SHORT REPAIR REPLACE DRIVE CONTROL LOGIC CARD CHECK POWER ON LAMP VERIFY B3 TS SECURE CHECK R27 ON DRIVE CONTROL LOGIC REMOVE BOTTOM COVER IS 15V RAW AT CARTRIDGE SOLENOID NO IS REPAIR 15V 15 REGULATOR OR F2 ON POWER NAC YES REPLACE POWER SUPPLY OK PS SUPPLY SUPPLY NO PLACE CHECK AC VOLTAGE ON POWER TRANSFORMER ISOLATE AND REPLACE DEFECTIVE PART IN AC INPUT CIRCUIT YES ISOLATE N SHORT NO CARTRIDGE UNLOCK LIGHTS ISOLATE REPAIR OPEN OR FAULTY SOLENOID YES ISOLATE OPEN IN 15 RAW CIRCUIT OPEN DOOR INSEAT CARTRIDGE DOOR YES UNLOCKED NO REMOVE TOP COVER IS 15V RAW AT CARTRIDGE SOLENOID 2 NO VERIFY B3 IS SECURE IF OK REMOVE BOTTOM COVER IS F4 ON POWER SUPPLY x gt YES REPLACE FUSE NO NO ES ISOLATE SHORT SM 2020 MOTION ERRATIC YES NO 3 72 CLOSE DOOR REMOVE TOP COVER OBSERVE CARRIA
19. READY NO CONTROLLER SELECTS READ CONTROLLER SENDS WRITE HEAD WRITE GATE AND CRC BYTES CONTROLLER SENDS READ CONTROLLER GATE INACTIVATES WRITE GATE CONTINUE TRIGGER 25 uSEC ERASE GATE DELAY ONE SHOT NEXT SECTOR REQUIRED NEXT SECTOR REQUIRED YES CONTROLLER SENDS WRITE GATE GENERATE DRIVE READY ERASE GATE FOR NEXT COMMAND FROM CONTROLLER MORE YES THAN ONE HEAD SELECTED MAKE DRIVE CONTROLLER SENDS READY AND DOUBLE FREQUENCY ACCESS READY WRITE DATA TAAGTIVE CONTINUE ALL DATA WRITTEN MANUAL INTERVENTION REQUIRED SM 2020 SERIAL WRITE DATA AS ASSEMBLED BY CONTROLLER DOUBLE FREQUENCY WRITE DATA FROM CONTROLLER NRZ WRITE amp READ CURRENT TO READ WRITE HEAD DOUBLE FREQUENCY READ DATA RAW DATA SERIAL READ DATA TO CONTROLLER 3 66 Disc Storage Unit TRANSFORMATION FROM BINARY TO RECORDING SIGNAL TO READ SIGNAL TO BINARY 1 1 Figure 3 39 0 0 1 1 0 0 1 1 Write Function Sheet 1 Disc Storage Unit DRIVE CONTROL LOGIC CONTROLLER READ WRITE CABLE 2 J2 SELECT HEAD 0 SELECT HEAD 1 HEAD SELECTION DECODER SELECT HEAD 2 SELECT HEAD 3 XDSEL B6 XHSEL XWDAT B7 XWRGT SELECT FIXED DISC SELECT LOWER HEAD B19 DOUBLE FREQUENCY WRITE DATA ADD WRITE CURRENT CYL BIT 256 Lo FIG 3 36
20. SET CYLINDER 150 NS CYLINDER ADDRESS REGISTER PREVIOUS ADDRESS NEW ADDRESS DRIVE SELECT WRITE GATE CONTROLLER TO DRIVE ERASE GATE CONTROLLER TO DRIVE DRIVE SELECT READ GATE SELECT HEAD SECTOR PULSE SM 2020 FLOW AND TIMING DIAGRAMS EE 200ns a JJ bend i TYPICAL INITIALIZATION TIMING STABLE STABLE oe MUST REMAIN ACTIVE 200 NS MINIMUM 0 5 100 15 500 NS L MAX IMUM NEW ADDRESS TRACK fae TT or zns 25 us MINIMUM MUST BE DOWN AT LEAST 40 uS PRIOR TO A READ OPERATION WRITE DATA OPERATION 46 20 5 us pi ele LU gt e 20 us MINIMUM cute READ DATA OPERATION 3 58 CONTINUE NEW ADDRESS SEQUENCE CONTROLLER SELECTS DRIVE WAIT ARE DRIVE READY AND ACCESS READY CONTROLLER SENDS NEW ADDRESS AND SET CYLINDER GENERATE LOAD CYLINDER REGISTER TRIGGER 200 MSEC DELAY NORMAL SERVO ARITHMETIC LOGIC AND SERVO LOOP CONTROL ACTUATOR ACCESS READY INACTIVE 200 MSEC DELAY OVER IS ARRIVAL LATCH SET GENERATE ACCESS READY DRIVE CONTROL TRANSFERRED TO CONTROLLER Figure 3 35 LATCH SET INCOMPLETE DRIVE HOME ACCESS READY DRIVE CONTROL TRANSFERRED TO CONTROLLER Start START UP
21. bit cells become smaller for each successive higher track number Bit cells are also smaller when the number of tracks per inch increases Since ultimately the retrieval of the recording in a bit cell is the function of a drive greater precision is required of drive operation as the number of available bit cells on a disc is increased Figure 1 5 shows typical construction details of a disc cartridge The plastic cartridge consists of two pieces with a door in each The lower half of the cartridge has an air door that is forced upward toward the disc by the drive air flow The upper half of the cartridge has a disc access door which is raised by levers attached to the drive as the cartridge is inserted in the drive When the disc access door is raised the disc is exposed and the opening becomes the head access area The disc assembly rests in a molded depression surrounding the Sector ring This arrangement keeps the disc edges from coming in contact with the edge of the cartridge Forty seven of the disc sectors are identified by notches SM 2020 Disc Storage Unit CYLINDER 202 405 TRACK 0 UPPER HEAD TOP SURFACE ME TRACK O LOWER HEAD k I CYLINDER 0 CYLINDER 202 405 INDEX SLOT SECTOR SLOT Z Ex END OF COATING NN TRACK 200 TRACK 400 STRADLE RIWELENMENT IW ELEMENT ERASURE de CENTER TRACK D CENTER TRACK TRACK ADIACENT TRA
22. switches to 64 32 8 and 1 to ON 128 64 16 and 2 to ON for Model 2X15 200 Set test module SELECT CYLINDER switch ON Press test module RESET pushbutton Press test module INITIATE push button The servo drives the heads to Cylinder 105 210 Set the test module SELECT CYLINDER switch to the OFF position a b Set the test module switches HEAD 1 and HEAD 2 to the OFF position Set the SET HD SCTR switch ON The top head of the removable disc is now enabled to read Disc Storage Unit SM 2020 Table 3 4 Removable Disc Head Adjustment continued 11 Turn head 0 adjusting screw clock wise until display begins to take shape of the waveform shown in figure 3 18 Figure 3 18 Waveform Head 0 0003 Inch from Cylinder 105 210 12 Continue turning the screw clock wise until the oscilloscope display resembles the waveform shown in figure 3 19 Figure 3 19 Waveform Head 0 0001 Inch from Cylinder 105 210 3 33 SM 2020 Disc Storage Unit Table 3 4 Removable Disc Head Adjustment continued 13 Make final adjustments on the screw by making the A value equal the value maximum allowable difference is 10 Figure 3 20 Waveform for Correct Head Alignment 14 Back off head adjusting screw 1 2 The head assembly is held in position turn by the head clamp 15 Using torque wrench torque head a Ensure tightening of the clamping clamping screw to 8 inch pounds screw d
23. sz Pr MUST BE DOWN AT LEAST 40 PRIOR TO A READ OPERATION WRITE DATA OPERATION 46 20 5 us MM ni 20 us MINIMUM n READ DATA OPERATION 3 58 NEW ADDRESS SEQUENCE CONTROLLER SELECTS DRIVE WAIT ARE DRIVE READY AND ACCESS READY CONTROLLER SENDS NEW ADDRESS AND SET CYLINDER GENERATE LOAD CYLINDER REGISTER TRIGGER 200 MSEC DELAY CONTINUE NORMAL SERVO ARITHMETIC LOGIC AND SERVO LOOP CONTROL ACTUATOR ACCESS READY INACTIVE 200 MSEC DELAY OVER Is ARRIVAL LATCH SET Is ARRIVAL LATCH SET GENERATE ACCESS READY NO SET SEEK INCOMPLETE DRIVE CONTROL DRIVE ROME TRANSFERRED OP AND TO CONTROLLER ACCESS READY DRIVE CONTROL TRANSFERRED TO CONTROLLER TURN OFF NORMAL SET TO CARTRIDGE UNLOCK MOTOR SWITCH ON SETS LOAD HEADS LOW DRIVE READY INACTIVE DRIVE READY IVE READY DARK DRIVE HOME OP SET LOW INITIALIZATION LATCH SET REGISTERS SET FOR TRACK 000 DRIVE HOME OP SUBSTITUTED FOR BIT 32 OF PRESENT CYLIN DER ADDRESS REVERSE DRIVE TO ACTUATOR WAIT 000 DETECTED YES RESET INITIALIZE LATCH CARRIAGE MOVES TO REAR CRASH STOP WAIT UE DELAY OVER YES 5V SUPPLY DIS ABLED CARTRIDGE UNLOCK SOLENOID ENERGIZED CARTRIDGE UNLOCK LIGHTED WAIT So DELAY OVER 2 YE
24. 10 16 4 12 LED DRIVE 18 ARRIVAL ZONE K E HOME POSITION F 7 M L H K E SERVO F NO 1 N LINEAR TACHOMETER POSITION DRIVE Me Pu gt 76 gt a SHAPED ERROR TACHOMETER DRIVE REVERSE LATCH SET FORWARD LATCH SET REVERSE PREAMP DRIVE FORHARD PREAMP DRIVE 7 PREAMP DRIVE B5 BS CURRENT FEEDBACK SUPPLY POWER SAFE I B3 B3 FRONT p MOTOR SWITCH ON SERVO NO 2 PANEL READ GATE TRIGGER 5 5 READ DATA LATCH 5 VFO IF READ CLOCK 9 READ DATA 9 K READ CLOCK 2 A2 Al 8 RAW DATA 5 HEAD 0 SELECTED HEAD 1 SELECTED HEAD 2 SELECTED HEAD 3 SELECTED m 18 WRITE CURRENT SELECT HEAD 0 ERASE CURRENT READ SIGNAL DRIVE 21 CONTROL WRITE CURRENT SELECT HEAD 1 ERASE CURRENT READ SIGNAL LOGIC READ WRITE AMPLIFIER WRITE CURRENT SELECT HEAD 2 ERASE CURRENT READ SIGNAL WRITE CURRENT SELECT HEAD 3 ERASE CURRENT READ SIGNAL gt 1 3 41 3 70 SM 2020 Disc Storage Unit B4 M A M A 7 x 7 5 5 SELECT DRIVE READY SHUTTER 3 2 6 SELECT ACCESS READY IE EEE TEN 10 10 DRIVE ACCESS READY 0 16 DINEAR CONE ENABLE 16 SERVO CONTROL SELECT SEEK INCOMPLETE M M m FORWARD DRIVE 12 1 18 SHAPED ERROR 18 10516 READ DATA LED DRIVE READ CLOCK A B 4 13 REVERSE DRIVE 13 SECTOR REMOVABLE ARRIVAL ZONE INDEX REMO
25. 1K CR20 1N4002 01 R74 R76 if 25 v 2N4401 R7 MOTOR SWITCH ON lt pis R75 1K REVERSE PREAMP DRIVE lt 1 6 FORWARD PREAMP DRIVE lt 8 70 SPIN SPEED SM 2020 15V UNREG 15V REG RE 15V UNREG R15 R16 ey 100 470 CR10 1462318 15V UNREG 2 3 NON LM723 I Di BH 45V REG 2 INV P1 5 gt POWER R70 10K 15V DRIVE HOME 15V RAW SAFE 1 023 2N4401 R80 R78 25 c8 2N5192 REI 470 1K 0 01 772 N C14 2K 07 921 100pf P1 2 gt 15V TP1 MEN 2N4401 248982 V RAW 5V REF CR13 R77 1N3064 SN 1N4742A 25 29 2N5195 5V REF 12 i R79 10K 15V UNREG R68 gt 200 767K V CRU Un 1N4002 23 37 R25 1 00K E13 HEAD 19 3 POSITIONER 200K 0 1 ACTUATOR CRI6 1N4002 15V REG R66 ba FEEDBACK 220 ve CR22 9 5 1N3064 5V UNREG 4 R7 15V REG I 100 1K 15V UNREG ed R48 C15 330 0 1 V ut CRB LN723 1N5232B ION 5 6V 5 1 2 AC POWER DELAY ver 435 RELAY VN REG RJ 2403 15 CR20 uS RI CR19 52 3K c 1N4002 d 0 01 R74 MAUI R76 i C20 ik 30 E6 50 R75 1K Figure 3 42 Power Supply Circuit Card Schematic Diagram 3 71 VERIFY POWER OFF CARTRIDGE UNLOCK SET FRONT PANEL POWER SWITCH TO POWER ON LIGHTS YES RECHECK BACK
26. 3 24 3 11 Shutter Mounting Screws D EAS AN ENE TESE 3 25 3 12 Safe Waveform Too Much Space ard delar f r Ce Jak 3 26 3 13 Correct and Unsafe Waveforms 3 27 3 14 APG Waveform ew 502 QUU GATES SE 3 28 3 15 TP7 Waveform SE ge 3 29 3 16 Combined TP6 and TP7 Waveforms Seb rae hn AV ay ae var Ao Es shores 2 13529 3 17 Head Adjusting Screw Location s 3 31 3 18 Waveform Head 0 0003 Inch from Cylinder 105 210 3 33 3 19 Waveform Head 0 0001 Inch from Cylinder 105 210 3 33 3 20 Waveform for Correct Head Alignment 3 34 3 21 Timing Pulse Waveforms Sa sai Meg 3 36 3 22 Access Time Waveforms er dy ais 3 39 3 23 Mounting Screws for Head Clamps and Adjusting Bracket ios 3 41 3 24 Head Removal and Replacement 3 41 SM 2020 Disc Storage Unit LIST OF ILLUSTRATIONS continued Figure 3 25 Drive Control Logic Circuit Card Connector Location 3 44 3 26 Actuator Mounting Screws AE 3 46 3 27 Optical Positioning Transducer Removal and Replacement pi dd val Sats 3 46 3 28 Shutter Removal Crash Stop and Shutter EE Bracket Mounting Screws ver QE ee Oe jus lt an at 3 48 3 29 Spin Motor Mounting Screws C oder 3 49 3 30 Fixed Disc Removal Fixed Disc Sector Transducer and Sector
27. 30 5 microseconds from the start of sweep Increase or decrease the delay a Turning adjusting screw clockwise of head 0 or head 1 TIMING PULSE increases the time between begin by adjusting R3 on the A5 circuit ning of sweep and the TIMING PULSE card Observe oscilloscope pattern while performing the adjustment NOTE Since head 0 and head 1 TIMING PULSE delays are controlled by R5 it may be necessary to alter nately switch from head 0 to head 1 to obtain the CORRECT waveform figure 3 21 Set up oscilloscope to measure Channel 1 014 pin 9 on 5 circuit index delay one shot output card Sync 1 of AS circuit card Vertical 1 V division Time Base 50 uSec division e Sync EXT Adjust R22 on AS circuit card for Adjusts delay from index pulse to 205 microsecond negative pulse forty eighth sector pulse Check equal spacing of sector Channel 1 V3 pin 6 on A5 circuit pulses card Time Base 1 mSec division Verify equal spacing between pulses Time Base 5 mSec division Check for equal spacing Readjust R22 if necessary to obtain equal spacing between sector pulses 3 17 ACCESS TIME ALIGNMENT The access time alignment should be performed whenever the actuator the A3 circuit card or the A4 circuit card is replaced 3 37 SM 2020 Table 3 6 Disc Storage Unit Access Time Alignment Procedure Remarks 3 38 Remove power and extend drive to obtain access to back of drive Re
28. 5 1 4w Resistor RC07 2K 5 1 4w Resistor 7 1 8K 5 1 4w Potentiometer 1K Resistor RCO7 5 1K 5 1 4w Resistor RN55D 576 ohm 1 1 8w Quantity Ref Ref FS EA HH Uu e NNE NAs Disc Storage Unit Parts List for Power Supply Circuit Board figure 4 24 continued Reference Designator R18 R19 R30 R20 R21 R25 R22 R23 R52 R58 R80 R87 R88 R54 R55 R59 R61 R68 R60 R62 R66 R69 R90 R70 R73 R83 R84 R71 R72 R76 R78 R79 R81 R82 R86 R89 U1 U2 U4 U3 US U6 Part No 11551 16728 11454 10849 11466 11144 10954 11051 10947 10060 11049 11173 10161 11094 10017 10032 16623 10233 16625 10101 10013 10069 10212 10039 10063 10434 10053 16731 16624 60303 60335 60358 17025 Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Part Name RN60D 3 32K 1 1 4w 4 ohm 5 7w RN60D 2 00K 1 1 4w RN55D 1 00K 1 1 8w RN60D 2 67K 1 1 4w RN55D 887 ohm 1 1 8w RN55D 2 00K 41 1 8w RN55D 3 32K 1 1 8w RN55D 301 ohm 1 1 8w RCO7 3K 5 1 4 RN55D 3 16K 1 1 8w RN55D 56 2K 1 1 8w RCO
29. A B D l l REVERSE A B l 1 FORWARD A B l 24 6 REV A B f l lL A B 0 Tf l LNS r J 1 FOWARD A B J 1 i reverse LT u f LT REV u U U24 12 FWD ea te A B D J 1 1 1 1 1 cowo 1 1 LE 1 1 I i i 7 i I i 1 1 1 1 REVERSE A B l l FWD U24 8 REV U UI U e ETT A B D i Wl ee pb FORWARD A B T err REVERSE A B k FWD REV u LI U22 12 3 60 HMTP HOME POSITION TRACK ZERO oA B A B A B LINEAR SIG A B LOGIC A B LOGIC 2 2 Figure 3 36 Tri SM 2020 FLOW AND TIMING DIAGRAMS FOR HEAD POSITIONING FUNCTION DIRECTION SENSE AND COUNT CONTROL pe TETTE Que Ga ep wet COUNT PULSE FWD 1 J COUNT PULSE REV J LINEAR ZONE ENABLE IS ACTIVE FOR 1 25 MILS EITHER SIDE OF TRACK CENTER TRACK CENTER DEFINED BY A B LINEAR SIGNAL L f l f LOT L HE qe I 1 1 1 1 1 1 1 1 T i i 1 1 1 1 I i l CROSSING ZERO ARRIVAL ZONE A B D IS ACTIVE FOR 0 56 MIL EITHER SIDE OF REVERSE A B a ea TRACK CENTER FORWARD A B 1
30. Alignment continued 4 10 Remove six screws securing the component cover to the chassis and remove cover Remove four screws securing the drive control logic card to the mounting brackets and slide the card assembly out of the way Manually position the carriage assembly against rear crash stop Using a dental mirror verify that shutter assembly is not broken and that a clearance exists between the mask and shutter by sighting down from rear of drive toward the disc spindle figure 3 9 Set ac switch on rear panel to ON position Set power switch to the POWER ON position Connect scope probe between TP1 on the A4 circuit card and oscillo scope channel 1 This permits access to transducer block and shutter Remove Read Write circuit card from connector of the drive control logic card Replace the shutter if it is broken or scratched If clearance does not exist between shutter and mask perform steps 8 9 16 17 and 18 before performing step 10 MASK SHUTTER Figure 3 9 Shutter Mask Spacing a TP1 on the A4 circuit card is HOME POSITION b Connect ground lead to SERVO GRD on component side of drive control logic card 3 23 SM 2020 Disc Storage Unit Table 3 3 Optical Transducer Shutter Alignment continued Procedure Remarks c Adjust oscilloscope to observe a 0 volt to 5 volt logic level 11 Loosen screw holding transducer a Keep transducer bl
31. EE Be ee cas a S W 2 1 2 2 2 Cartridge Unlock QUSS E Det 2 2 2 2 3 Reddy sp E 2 2 SECTION 3 MAINTENANCE 3 1 Scope cL 3 1 3 2 Special Cautions He AE Re Me 3 3 1 3 3 Detailed Functional Description Bee a Wo RUM del Teo uv Us 3 2 3 4 Power Function Vee og a 3 3 3 5 Start Stop and Status Puerro Sy Deke 22 ia vao fis Im 3 4 3 6 Head Positioning Function 3 6 3 6 1 Track Number and Head Position Comparison Circuits 3 6 3 6 2 Head Position Control Circuits es 3 7 3 7 Sector and Speed Detection Function s 3 9 3 8 Write Function gt 6 5 10 3 9 Read Function s s s s s s s n n ng 3 11 3 10 Troubleshooting PE gm IC tg NOUS 3 11 3 11 Special Tools Test Equipment and Materials vade EE Se 3 11 1 Special 015 3 12 3 11 2 Cleaning Materials SANT Dui De yal eid 3 13 3 11 3 Fixed Disc Replacement Kit ET 0 3 13 3 12 Preventive Maintenance 25 5 tai 5 30 deo ENG 3 13 3 13 Cleaning Shutter and Removable DISCS Fa VE V ox 3S ee 3 21 3 13 1 Shutter Cleaning Procedure 6 ss so n 3 21 3 13 2 Removable Disc Cleaning Procedure ee eee 3 21 3 14 Optical Transducer and Shutter Alignmen
32. FIRST FIXED DISC SECTOR PULSE SETS STOPPED LOW TRIGGER 1 MINUTE DELAY SET DRIVE HOME OP LOW SET INITIALIZE LATCH TRIGGER 200 MSEC DELAY SET CYL INDER REGISTER TO ZEROES SET PRESENT CYLINDER ADDRESS TO ONES SUBSTITUTE DRIVE HOME OP FOR BIT 32 OF PRESENT CYLINDER ADDRESS CONTINUE REVERSE DRIVE TO ACTUATOR CARRIAGE MOVES PAST HOME TO REAR CRASH STOP 200 MSEC DELAY OVER SET DRIVE HOME OP HIGH REMOVING REVERSE DRIVE TO ACTUATOR WAIT ENERGIZE DOOR UNLOCK SOLENOID CARTRIDGE UNLOCK DISABLE 5V START UP MAKE LOAD HEADS ACTIVE HIGH MAKE DRIVE FORWARD TO ZERO LOW AND SUBSTITUTE FOR BIT 16 OF CYLINDER REGISTER CONTINUE FORWARD DRIVE TO ACTUATOR TRACK 000 DETECTED RESET INITIALIZE LATCH MAKING DRIVE FORWARD TO ZERO HIGH REPEAT CONTINUE NORMAL SERVO ARTHIMETIC LOGIC AND SERVO LOOP CONTROL ACTUATOR TRACK 000 5 TRIGGER ARRIVAL DELAY ONE SHOT WAIT 6 MSEC d ELASPED YES ARRIVAL NO STILL ACTIVE YES SET ARRIVAL FLIP FLOP WAIT R W SAFE 1 AND R W SAFE 2 ACTIVE GENERATE DRIVE READY LIGHT DRIVE READY GENERATE ACCESS READY DRIVE CONTROL TRANSFERRED TO CONTROLLER DR HOME OP HOME 05 HOME POS DLYD ARRIVAL HDS LOADED DR FWD TO TRACK INITIALIZATION OP DRIVE SELECT ADDRESS BUS
33. I Pulley 5 5 3 51 3 31 Fixed Disc Removal Receiver Gover EE Mee 3 52 3 32 Fixed Disc Removal Fixed Disc Cover N 3 52 3 33 Fixed Disc Removal Disc Spindle Mounting Screws pn 3 53 3 34 Power Function Bod mel ee 3 57 3 35 Start Stop and Status Function 2 Sheets 2 3 58 3 36 Track Number and Head Position Comparison Circuits 2 Sheets 3 60 3 37 Position Control Circuits 2 Sheets 3 62 3 38 Sector and Speed Detection Function 2 Sheets 3 64 3 39 Write Function 2 Sheets 3 66 3 40 Read Function 2 Sheets e 3 68 3 41 Interconnection Diagram 3 70 3 42 Power Supply Circuit Card Schematic Diagram et US 3 71 3 43 Troubleshooting Flow Diagram 2 Sheets 3 72 4 1 Disc Drive Assembly ux XM 4 3 4 2 Receiver Assembly 73170 4 5 4 3 Fixed Disc Cover Assembly 73180 Right Side Le SE 4 7 4 4 Fixed Disc Cover Assembly 73180 Left Side 4 9 4 5 Door Assembly 75160 Ge tay 4 11 4 6 Chassis Assembly 73080 Top View GE BS eae E 4 13 4 7 Actuator Assembly 73020 4 15 4 8 Actuator Motor Assembly 742226 4 17 4 9 Chassis Assembly 73080 Bottom View ee 4 19 4 10 Chassis Assembly 73080 Partial es n 4 21 4 11 Blower Assembly 73120
34. ORANGE JUMPER BLUE WIRE FROM SPIN MTR Figure 4 17 Bottom Panel 73080 4 28 Disc Storage Unit SM 2020 Parts List for Drive Control Logic Circuit Card figure 4 18 Reference Designator Part No Part Name Quantity 74450 Drive control logic assemble Ref 74291 Circuit card P A0 thru AS 2885 Connector P C board 44 pin 6 B1 thru B7 TP1 thru 18521 Contact pins 52 TP10 TP12 thru TP17 C1 C2 C3 C14 C15 C16 12720 Capacitor 150D 6 8uf 20V 8 C39 C40 i 4 9 11 17 23 24 12812 Capacitor CER 0 1uf 50 17 C27 C28 C29 C30 C33 C35 C36 C37 C38 C43 C45 C5 C6 C12 C15 C20 C21 12641 Capacitor DM15 500pf 500V 9 C22 C32 C44 7 8 19 25 26 12534 Capacitor 192P 0 001uf 200V 5 10 12814 Capacitor CER 0 22uf SOV 1 C18 1206 Capacitor 150D 220uf 10V 1 C31 C41 12818 Capacitor CER 1 0uf 50V 2 C34 12801 Capacitor CER 0 01uf SOV 1 C42 12723 Capacitor 150D 22uf 20V 1 C46 12661 Capacitor DM15 3300pf 500V 1 CR1 CR2 CR3 13007 Diode 1N4002 3 J1 P1 26071 Connector socket 50 pin 2 R1 R8 R11 R13 R14 R15 10053 Resistor RC07 1 5K 5 1 4w 17 R21 R25 R26 R28 thru R35 R2 R3 R17 R18 10022 Resistor 07 75 ohm 5 1 4w 4 R4 thru R7 R17 10028 Resistor RC07 130 ohm 5 1 4w 5 R9 10148 Resistor RC07 910K 5 1 4w 1 R10 R20 10111 Resistor RC07 27K 5 1 4w 2 R12 10246 Resistor RC20 750 ohm 5 1 2w 1 R19 10896 Resistor RN55D 17 4K 1 1 8w 1 R22 R23 R24 10432 Resistor RC32 20
35. a connector adapter attached to Drive Control Logic boards having edge connectors for J1 and J2 Add the following note to figures 3 35 3 36 and 3 38 through 3 41 NOTE PRINTED PIN NUMBERS LETTERS SHOWN FOR DRIVE CONTROL LOGIC BOARD APPLY TO BOARDS HAVING EDGE CONNECTORS FOR Ji AND J2 ADDED PIN NUMBERS APPLY TO BOARDS HAVING INTEGRAL MALE FEMALE CONNECTORS FOR J1 AND J2 Make the following pen and ink changes Figure 3 34 Add ORN to wire from Power Supply E10 to Drive Control Logic and change 5V to 15V Add BLK to wire from Power Supply E11 to Drive Control Logic 15V Add RED to wire from Power Supply E9 to Drive Control Logic 5 Figure 3 35 sheet 2 Near left margin add 33 below a and 46 above Z on J1 J2 Near right margin add 37 below 14 36 above 15 and 39 above 12 on J1 J2 Add B20 to J2 for XARDY Figure 3 36 sheet 2 Near left margin add the following numbers on address lines to the left of J1 J2 6 for 0 10 for 1 7 for 2 11 for 3 4 for 4 8 for 5 5 for 6 9 for 7 and 26 for 8 Add B9 to J2 for XCYA8 Figure 3 38 sheet 2 Near left margin add 46 to XDRSO line near J1 J2 Near right margin add 14 below X 13 above J 12 above Y and 15 above in J1 J2 Figure 3 40 sheet 2 Near left margin add 49 below 6 32 above b 30 above P and 46 above Z in J1 J2 Near right margin add 38 below 18 and 35 above 17 in J1 J2 Figure
36. and reverse direction of the rotary actuator Read Write This circuit card contains the write amplifier write 73460 A3 safety circuits the head selection diode matrix the read signal conditioning and zero crossing detector circuits that convert signals read from the disc to RAW DATA VFO This circuit card contains the circuits that convert 73560 Variable the RAW DATA read from the disc into READ DATA and Frequency READ CLOCK signals Oscillator 1 Removable The removable disc sector transducer detects sector 73190 Disc Sector slots in the rotating skirt of the removable disc Transducer It is attached to the front of the fixed disc cover Assembly assembly near the removable disc skirt Fixed The fixed disc sector transducer detects sector slots 73606 Disc Sector in the rotating sector ring This assembly is attached Transducer to the bottom of the drive chassis near the sector ring Assembly of the fixed disc Power This circuit card contains the fuses and circuits that 73700 Supply provide the 15 volt regulated and the 5 volt regulated power used throughout the drive It also contains the head unload relay which causes the heads to retract from the discs during abnormal power conditions or when the discs are rotating at less than 70 of normal speed The power supply is mounted on the bottom of the chassis Switch Fuse This assembly consists of two slow blow fuses an ac 73418 power switch and a line filter Power Off T
37. be determined This is accompolished by synchronizing a variable frequency oscillator VFO to the raw data The VFO output is a double frequency clock 2F read clock synchronized to the raw data The oscillator on the VFO card is started by the read gate and delayed read gate The double frequency read clock from the VFO is compared to the raw data When the 2F read clock occurs too soon a lag correction signal is generated which changes the control current from a bidirectional current source This lowers the frequency of the oscillator Similarly a lead correction signal may be generated to increase the frequency of the oscillator The raw data is examined at the double frequency clock rate to create the restored data This read data is not synchronized to any timing in the controller or the CPU so a read clock 1F read clock is sent with the read data to the controller 3 10 TROUBLESHOOTING Troubleshooting is performed whenever a malfunction occurs and requires a thorough knowledge of normal drive operation In addition specific diagnostic test programs can significantly reduce the time needed to isolate troubles to a removable assembly In addition to the functional block and data flow diagrams figures 3 34 through 3 40 an interconnection diagram figure 3 41 and a power supply schematic figure 3 42 are provided as troubleshooting and repair aids 3 11 SM 2020 Disc Storage Unit In digital data processing equipment a fa
38. between Cylinder 50 and Cylinder 100 It is possible to obtain a pattern which looks similar to the correct pattern but with incorrect amplitude Ignore these positions and continue to adjust the shutter position until the correct amplitude is obtained then continue adjusting until the correct pattern is obtained GROUND GROUND 0 5V OR LESS 1 5V TO 1 9V CORRECT WAVEFORM DANGER SPACE IS 0 005 TOO LITTLE INCHES NOMINAL SPACE Figure 3 13 Correct and Unsafe Waveforms This reduces the shutter to mask space at the rear of the shutter If no clearance exists position the shutter slightly toward the actuator motor The Lissajous pattern will at first resemble the shape of the SAFE waveform figure 3 12 3 27 SM 2020 Table 3 3 Disc Storage Unit Optical Transducer Shutter Alignment continued Procedure Remarks 29 Repeat steps 26 through 28 until the CORRECT Lissajous pattern is obtained figure 3 13 30 Repeat steps 26 through 29 while moving carriage back and forth between Cylinder 150 and 200 31 Verify that the CORRECT pattern is obtained as the carriage is moved through the range of travel from 000 to 200 32 oA and check steps a Connect TP7 on the A4 circuit card to channel 2 of the oscilloscope b Verify that the TP6 waveform figure 3 14 has a peak to peak amplitude of 1 5 volts minimum to 2 0 volts maximum as the carriage is moved back and forth between
39. carriage assembly toward Cylinder 100 loosen rear mounting screw figure 3 11 and position the rear of the shutter assembly toward the actuator Tighten both mounting screws snug a This connects B to the oscillo scope vertical deflection plates b Set vertical sensitivity to 0 5 V CM c Set ground tract at top graticule of scope d Input selector DC a Calibrate external horizontal input to 5 V division Connect TP7 A to oscilloscope horizontal deflection plates Time base EXT Coupling DC Slope Mode AUTO This reduces the shutter to mask space at the front end of the shutter 00 If no clearance exists position the shutter slightly toward the actuator motor The Lissajous pattern will at first reassemble the shape of the SAFE waveform shown figure 5 12 GROUND Figure 3 12 Safe Waveform Too Much Space Disc Storage Unit Table 3 3 SM 2020 Optical Transducer Shutter Alignment continued Procedure Remarks 24 25 26 27 28 Repeat steps 21 through 23 until the Lissajous pattern takes the shape of the CORRECT waveform figure 3 13 Position the carriage assembly to Cylinder 100 Loosen the rear shutter mounting screw and position the shutter slightly away from dc actuator motor Verify that clearance between the shutter and mask still exists While monitoring the oscilloscope display move the carriage back and forth
40. four wires from spin motor as follows a blue wire terminal 1 of spin motor start relay b red wire terminal 2 of spin motor start relay c black yellow wire terminal 7 of the power transformer 60 Hz configuration d green wire from spin motor frame Remove spin motor assembly through top of drive chassis qim ee ORIVE BELT ADJ SPRING SPIN MOTOR MOUNTING SCREW 4 SPIN LOADED MOUNTING BRACKET DRIVE BELT ADJ SCREW 3 Figure 3 29 Spin Motor Mounting Screws SM 2020 Disc Storage Unit 3 29 SPIN MOTOR REPLACEMENT 1 Perform in reverse order steps 7 through 10 of paragraph 3 28 2 Leaving the three screws that secure the spin motor spring loaded mounting bracket to chassis loose temporarily install the switch fuse assembly Ensure that the drive is in an upright position 3 Place the drive in normal operation by setting ac switch to ON position the power switch to POWER ON and the spin motor switch to CARTRIDGE LOCK position 4 Verify that the belt tension spring automatically shifts the motor to the correct belt tension 5 Remove ac power by setting the spin motor switch to CARTRIDGE UNLOCK position power switch to POWER OFF and ac switch to OFF position 6 Remove two screws securing switch fuse assembly to drive chassis 7 Perform in reverse order steps 1 through 6 of paragraph 3 28 3 30 FIXED DISC REMOVAL Replacement of the fixed disc requires that the fixed disc spindle a
41. on and power safe logic signals and the safety circuit which maintains power to the drive long enough to ensure head retraction in cases where the front panel power switch is set to POWER OFF before the carriage switch is set to CARRIAGE UNLOCK 2 The Start Stop and Status Function figure 3 35 includes the circuits that control start up and stop sequencing and the circuits that check drive status and generate appropriate status signals for the controller 3 The Head Positioning Function consists of the track number and head comparison circuits figure 3 36 and the head position control circuits figure 3 37 The track number and head comparison circuits generate a shaped error signal for the head position control circuits The shaped error signal usually is the result of the controller commanding the drive to move the read write heads to a different track This command results in there being a difference between the present cylinder address present head position and the address contained in the cylinder register new address During the drive start up sequence the shaped error is a result first of a drive home signal and second a drive to track 0 signal load heads During a stop sequence the shaped error is a result of a drive home signal The head position control circuits detect the direction and velocity of head motion the carriage shutter and read write heads all move together From this information and the shaped error sign
42. t 2 RESET HI ADDRESS LOAD CYL REG HI TO ONES MULTIPLE HEADS SEL INITIALIZE TRIGGER FIG 3 39 F F 200 MSEC FIG 3 39 ERASE TIME PRESET TRACK 0 POSIT TON gt 200 MSEC TO SEEK ARRIVE INCOMPLETE LATCH HOME DETECTOR SET FIG 3 36 FIG 3 37 ARRIVAL ACCESS ARRIVE READY IN TIME ARRIVAL DRIVE READY J1 LOAD CYL 32 CONTROLLER CABLE 32 INTERFACE SEL SET REGISTER CYLINDER E XSTCY SET CYCINDER DMA DISC CONTROLLER XDRS DRIVE SELECT SM 2020 BS 5V OFF B DRIVER B3 UNLOCK CARTRIDGE FRONT CARTRIDGE UNLOCK LAMP PANEL 15V CARTRIDGE UNLOCK SOLENOID POWER SUPPLY FIG 3 42 UNLOCK 1 CARTRIDGE HI 5 MOTOR SWITCH ON HI HI 15V RAW LOAD HEADS TP13 10 64 SEC DELAY BECOMES SHAPED ERROR FIG 3 37 FORWARD DRIVE DRIVE FIG 3 37 FORWARD TO ZERO BIT 16 SET CYLINDER REGISTER TO ZEROES DRIVE HOME 0 Ti M FAULT 1 SET 10 DETECT anl BECOMES SHAPED 000 TRACK 0 H1 SEEK INCOMPLETE HI Fer ED BIT 32 ERROR FIG 3 37 REVERSE DRIVE FIG 3 36 CYL REG DEC OF 91 4 SET SET PRESENT FIG 3 37 2 RESET HI Ane LOAD CYL REG DRESS TO ONES R W SAFE 1 FIG
43. the spin motor spring loaded mounting bracket to chassis loose temporarily install the switch fuse assembly Ensure that the drive is in an upright position Place the drive in normal operation by setting rear panel ac power switch to ON position the power switch to POWER ON and the spin motor switch to CARTRIDGE LOCK position Verify that the belt tension spring automatically shifts the motor to the correct belt tension Remove ac power by setting the spin motor switch to CARTRIDGE UNLOCK position power switch to POWER OFF and ac switch to OFF position Remove two screws securing switch fuse assembly to drive chassis Perform in reverse orders steps 1 through 6 above 3 55 Disc Storage Unit AC Sf CARTRIDGE LOCK CARTRIDGE UNLOCK SWITCH LINE FUSES RECEIVER INTERLOCK SWITCH BACK PANEL POWER SWITCH B3 MIR SW ON HI R W SAFE 2 HI MTR SW ON FIG 3 35 LINE FILTER POWER TRANSFORMER POWER SUPPLY 15 VOLT SUPPLY BRIDGE RECTIFIER 5 VOLT SUPPLY BRIDGE RECTIFIER DELAY RELAY DRIVER 15V UNREG DISABLE 5V TO DRIVE HOME AMP FIG 3 37 TO REVERSE AMP FIG 3 37 15 VOLT REGULATOR 15 VOLT REGULATOR TO FORWARD AMP FIG 3 37 5 VOLT REGULATOR 15V SERVO DRIVE CONTROL LOGIC B5 POWER SAFE FIG 3 35 FIG 3 39 FIG 3 37 15V RAW FIG 3 35
44. 0 ohm 5 1w 3 R27 10987 Resistor RN55D 24 9K 1 1 8w 1 Q1 12923 Transistor 2N5088 1 Q2 12921 Transistor 2N5192 1 U1 U2 U6 U7 17021 Integrated Circuit SN7405 4 U3 17008 Integrated Circuit SN7430 1 U4 031 035 U36 U43 U44 17001 Integrated Circuit SN7404 7 1045 US 18000 Integrated Circuit Resistor 1 5K 1 U8 U17 U30 U41 U48 U49 17002 Integrated Circuit SN7400 8 053 054 U9 U38 17055 Integrated Circuit 9602 2 U10 U21 U22 U33 U34 17003 Integrated Circuit SN7410 7 U40 U52 011 17033 Integrated Circuit SN7406 1 U12 U24 17020 Integrated Circuit SN74174 2 U13 U16 U25 17058 Integrated Circuit SN7483 3 U14 U20 U26 U29 17032 Integrated Circuit SN7486 4 015 027 17053 Integrated Circuit SN74193 2 018 17013 Integrated Circuit SN7476 1 019 17029 Integrated Circuit SN7414 1 023 037 17004 Integrated Circuit SN7420 2 U28 U32 U42 U50 U55 17042 Integrated Circuit SN7408 5 U39 17011 Integrated Circuit SN7474 1 U46 047 151 17024 Integrated Circuit SN7438 3 18650 Connector fast on 15 5 3 18631 Connector fast on GND 2 70315 Eyelet 5 27250 Key polarizing 6 25390 Washer fiber 2 4 29 SM 2020 Figure 4 18 916 1604 E pum ex den E men mer Drive Control Logic 73720 Disc Storage Unit Disc Storage Unit Parts List for Interface Circuit Card figure 4 19 Reference Designator C1 C2 C3 C4 C5 C9 C10 C11 18 22 23 C6 C16 7 13 14 19
45. 1 4 25 micro second erase gate delay one shot is triggered at the end of the write gate so the gutter is erased to the end of the recorded area This is necessary because the erase head is physically placed behind in the direction of disc rotation the read write head 3 10 Disc Storage Unit SM 2020 3 9 READ FUNCTION figure 3 40 As in the write function the controller causes the read write heads to be positioned over a specific track and by use of the index and sector pulses locates the start of the specific beginning sector where the required data is stored The same circuits decode the head selection signals select fixed disc and select lower head for reading as for writing paragraph 3 8 Drive select is active and the controller makes the read gate active at the beginning of the first sector to be read The read signal from the selected read write head is processed by the read signal conditioning circuits and converted to logic levels by the zero crossing detector The raw data signal from the Read Write card is essentially the same as the double frequency write data signal which caused the data to be recorded in the sector However small variations in the disc rotational speed are common and this causes variations in the timing of bit cells In order to reconstruct the data originally used to generate the double frequency signal the signal from each bit cell must be identified so the logic state of the original data bit may
46. 20 NOTE Previously recorded data may be recovered from the fixed disc after head arm replacement by performing the following steps prior to installing component cover a Power up drive and install disc cartridge b Loosen the appropriate head clamp c Turn the head adjusting screw counterclock wise until screw just begins to bind d Load heads and enable appropriate head e Set up oscilloscope as in step 7 of table 3 4 except sync negative on pin 14 of 5 circuit card f Turn adjusting screw clockwise until maximum amplitude is obtained at track 0 g Tighten head clamping screw ensure that the amplitude remains maximum Perform disc diagnostic 3 22 ACTUATOR ASSEMBLY REMOVAL Remove disc cartridge from drive Remove drive power and extend drive to obtain access to back and bottom of drive Remove nine screws securing bottom cover to drive chassis Remove the red lead from E13 and the black lead from E14 on the power supply card figure 3 8 Remove six screws securing component cover to drive chassis Remove cover Remove screw securing head cable bracket to drive chassis figure 3 1 Remove four screws securing drive control logic circuit card to mounting bracket Remove Al through 5 circuit cards from drive control logic circuit card 3 43 SM 2020 Disc Storage Unit 9 Remove head connector cables JO through J3 from the A2 circuit card figure 3 1 10 While holding carriage assembl
47. 3 SELECT READ INTERFACE RED READ TP16 pe m _ 1F READ CLOCK READ DATA READ DATA LATCH VARIABLE FREQUENCY OSCILLATOR AND DATA SYNCHRONIZING RAW DATA CLOCK 1F READ CLOCK DATA READ DATA LATCH OSC START LATCH READ GATE TRIGGER LAG CORRECTION CUR CONTROL OSC CORRECTION LEAD CORRECTION Figure 3 40 SM 2020 DISC Jt CONTROLLER 32 CABLE 32 18 punts B15 DMA DISC CONTROLLER 7 XSRD 811 Read Function Sheet 2 3 69 SELECT DRIVE READY SELECT ACCESS READY INDEX Fre FIXED DMA DISC CONTROLLER DRIVE CONTROL LOGIC SET CYLINDER lt X r lt DMA DISC CONTROLLER cy Z gt P DRIVE SELECT 0 INTERFACE RESTORE DRIVE SELECT 1 mmmspsa Ress 256 DRIVE SELECT 1 SECTOR REMOVABLE 70 SPIN SPEED SPIN STOPPED DRIVE SELECT LINE TERMINATION ONLY G C x AN m B7 REHDVABLE TRANSDUCER SIGNAL REMOVABLE DISC 7 TRANSDUCER SIGNAL REMOVABLE DISC TRANSDUCER FIXED TRANSDUCER SIGNAL FIXED DISC DISC 3 TRANSDUCER SIGNAL FIXED DISC SM 2020 7 7 ECTS ER EN 5 5
48. 3 36 d bise MULTIPLE HEADS SEL Suda SEL DRIVE READY 31 CONTROLLER INITIALIZE TRIGGER FIG 3 39 SET LO J2 CABLE 2 uS HOME FIG 3 39 EUSE TINE ENABLE XDRDY B10 PRESET POSITION CLK RESET DELAY pe MSEC TO SEEK ARRIVE INCOMPLETE DMA DISC LATCH CONTROLLER F E R W SAFE 2 TOR ENABLE SEL ACCESS READY ENABLE XARDY SET LO SET 10 ACCESS READY ARRIVE IN TIME 5 INTERFACE B NOT USED ACCESS READY ARRIVAL DRIVE RFADY LOAD CYL REGISTER FIG 3 36 FIG 3 37 FIG 3 39 INITIALIZATION OP FIG 3 37 F AS CYLINDER SERVO NO 2 Figure 3 35 Start Stop and Status Function Sheet 2 3 59 CONTROLLER SELECTS DRIVE WAIT ARE DRIVE READY AND ACCESS READY GENERATE LINEAR ZONE ENABLE LINEAR SIGNAL YES USED FOR BOTH POSITION EE CONTROLLER SENDS ERROR AND NEW ADDRESS AND VELOCITY SET CYLINDER CARRIAGE MOVES 0 69 MIL TOMARD TRACK CENTER GENERATE ARRIVAL __ __ ZONE TRIGGER 6 MSEC ONE SHOT 5 6 MSEC OVER NEW CYLINDER ADDRESS SET INTO REGISTER CARRIAGE MOVES BACK TOWARD CENTER OF TRACK SET 200 MSEC DELAY ACCESS READY INACTIVE COMPARE PRESENT ADDRESS WITH NEW ADDRESS SIGN OF DIFF ERENCE CAUSES ERROR POLARITY THAT WILL DRIVE ACTUATOR TO WARD ERROR REDUCTION YES ARRIVAL MSEC MAGNITUDE OF at ZONE STILL AC
49. 3 40 On lines to left of J1 J2 add the following 33 near 11 near 5 9 near 3 32 near b 6 near T 4 near U 26 near 7 49 near 6 10 near S 8 near 8 50 near N 31 near 9 7 near R 5 near 4 30 near P 46 near Z Gn the lines to the right of J1 J2 add the following 37 near 14 35 near 17 13 near J 39 near 12 138 near 18 15 near K 36 near 15 14 near X 12 near Y
50. 66 Part Name Cam cartridge door open Screw Washer lock Standoff Micro switch Screw Plate micro switch mounting Screw Handle latch assembly Seal strip assembly Cartridge guide Screw Screw Grommet Transducer assembly Sector transducer Nut Cover fixed disc Disc Storage Unit Quantity PNR L IN PRP DRE BRE Disc Storage Unit SM 2020 Figure 4 3 Fixed Disc Cover Assembly 73180 Right Side SM 2020 Parts List for Fixed Disc Cover Assembly Left Side figure 4 4 Reference No 00 10 G Part Number 73297 73185 19120 13313 18390 19150 73188 73255 73342 13330 Part Name Clamp cable Guide cartridge Grommet Screw Plug keying Ring truarc Spring cam Cam cartridge door open Pivot cam Screw Disc Storage Unit Quantity ANKE r Disc Storage Unit ore E 3 fru RED ve Ed KEYING PLUGS DETAIL A DUCER CABLE CONN TO 18381 CONNECTOR Figure 4 4 Fixed Disc Cover Assembly 73180 Left Side SM 2020 SM 2020 Parts List for Door Assembly figure 4 5 Reference No V O NIQAUPRGUNKE Part Number 73292 73286 73285 14004 14025 14104 73268 14003 14024 14103 73269 73349 19248 73348 Part Name Strip attaching Window Handle door Washer plain Washer lock Nut Hinge right side Washer plain Washer lock Nut Hinge left side Shim up to 8 may be
51. 7 3 3M 5 1 4w RN55D 52 3K 41 1 8w RCO7 47 ohm 5 1 4w RCO7 200 ohm 5 1 4w RS 2C 0 25 ohm 3 6 5w RC20 220 ohm 5 1 2w RS 5 1 0 ohm 3 6 5w 07 10K 5 1 4w RCO7 33 ohm 5 1 4w RCO7 6 8K 5 1 4w RC20 30 ohm 5 1 2w RCO7 390 ohm 5 1 4w RCO7 3 9K 5 1 4w RC32 240 ohm 5 iw RCO7 1 5K 5 1 4w 25 ohm 5 10w RS 2C 0 5 ohm 3 6 5w Integrated circuit LM723 Integrated circuit LM307N Integrated circuit LM1458N Integrated circuit 7426 SM 2020 Quantity H H H H ki PR N H N NP 4 43 SM 2020 Disc Storage Unit ACT RETURN ACTUATOR 73750 9393 REG sv SEG TSV REG Figure 4 24 Power Supply 73700 4 44 Disc Storage Unit SM 2020 Parts List for Terminator Assembly figure 4 25 Reference Designator Part No Part Name Quantity C1 Capacitor CER 2200pf 50V 1 C2 Capacitor 150D 2 2uf 20V 1 J1 Connector AMP 5839001 1 R1 Resistor RC07 200 ohm 5 1 4w 1 R2 Resistor RC07 130 ohm 5 1 4w 1 U1 U2 Integrated circuit resistor pac 2 220 330 ohm Figure 4 25 Terminator Assembly 73710 4 45 basic Four Sg gt November 1 1974 To The User of SM 2020 Concurrent with publication of SM 2020 dated November 1 1974 two configurations of the Drive Control Logic board are being installed in Disc Drive Units The boards are interchangeable by virtue of
52. 92P 0 0022uf 10 80V 192P 0 033uf 10 80V CER 0 01uf 20 50V DM 470pf 5 500V Diode 1N3064 Transistor 2N5462 Transistor 2N4401 Transistor 2N4403 Transistor 2N5192 Transistor 2N5195 Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor RCO7 100K 5 1 4w RN60D 604K 1 1 4w RNSSD 301K 1 1 8w RN55D 150K 1 1 8w RN55D 75 0K 1 1 8w RNS5D 37 4K 1 1 8w RNS5D 18 7K 1 1 8w RNS5D 9 31K 1 1 8w RN55D 4 64K 1 1 8w RN60D 1 0M 1 1 4w RN55D 30 1K 1 1 8w RN55D 6 04K 1 1 8w RN55D 10 2K 1 1 8w RN55D 10 0K 1 1 8w RCO7 2K 55 1 4w RN55D 20 5K 1 1 8w RCO7 1K 5 1 4w RCO7 680 ohm 5 1 4w RCO7 1 8K 5 1 4w RN55D 12 1K 1 1 8w RNSSD 8 06K 1 1 8w RNSSD 28 0K 1 1 8w RN55D 4 99K 1 1 8w RNS5D 20 0K 1 1 8w RN55D 8 45 1 1 8w RCO7 22K 5 1 4w RCO7 470 ohm 5 1 4w 50 ohm 3 3 25w Potentiometer 5K 10 3 4w Resistor RN55D 17 4K 1 1 8w SM 2020 Quantity Ref Ref o PPNN m O0 DD ft ft H H HH QN P N AOAN 2 I 00 4 35 SM 2020 Disc Storage Unit Parts List for Servo Circui
53. 92P 0 0047uf 5105 80V 150D 6 8uf 205 20V 192P 0 012uf 210 80V 0 A Diode 1N3064 Diode 1NS231B 5 1V 5 Transistor 2N4401 Transistor 2N4403 Transistor 2N5195 Transistor 2N5462 Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor RN55D 10 0K 1 1 8w RCO7 2K 5 1 4w RC07 150 ohm 5 1 4w RN55D 4 75 415 1 8w RN55D 30 1K 1 1 8w RN55D 75 0K 1 1 8w RNSSD 200K 15 1 8w RN55D 25 5K 1 1 8w RN55D 200K 1 1 8w RN55D 3 40K 1 1 8w RN55D 7 68K 1 1 8w RC07 1 MEG 5 10 ohm 5 2w RC07 510K 5 1 4w 1 4w RN55D 20 0K 1 1 8w RN55D 6 65K 1 1 8w RN55D 4 99K 1 1 8w RN55D 2 87K 1 1 8w RN55D 3 01K 1 1 8w RN55D 100K 1 1 8w RN55D 2 94K 1 1 8w RN55D 36 5K 1 1 8w RN55D 1 00K 1 1 8w RN55D 3 01 1 1 8w RNSSD 90 9K 1 1 8w RN55D 499 ohm 1 1 8w RN55D 9 09K 1 1 8w RN55D 4 53K 1 1 8w RN55D 40 2K 1 1 8w SM 2020 Quantity Ref Ea ka RA Q4 N RS GI HEB EB B BRU CO Qo e SM 2020 Disc Storage Unit Parts List for Servo Circuit Card No 1 figure 4 20 continued Referen
54. ALTONS lt ular Sy GE Sox X EE a 1 6 1 3 Component Description EP MEE Ee 1 7 3 1 Six Month Preventive Maintenance be on JER GEA fas AA D 3 13 3 2 Twelve Month Preventive Maintenance 5 18 5 3 Optical Transducer Shutter Alignment 3 22 3 4 Removable Disc Head Alignment 5 50 3 5 Removable Disc Transducer Alignments 3 35 3 6 Access Time Alignment 3 38 LIST OF ILLUSTRATIONS Figure Page 1 1 Disc Storage Unit 1 1 1 2 Cartridge Receiver Area with Component Cover Removed 1 4 1 3 Disc Drive Bottom View 1 5 1 4 Disc Origanization RAGE fe uus 1 10 1 5 Disc Cartridge Exploded View umm 1 11 1 6 Comparison of Sizes Disc to Head Separation and Contaminants 1 12 1 7 Functional Block Diagram 1 14 3 1 Drive Component Identifier x ok ego ee boobs e N 3 14 3 2 Head Spacers Inserted Between Heads DD Ene Je So clase oi 3 15 3 3 Lubrication Locations EG fuut Ge feos 3 16 3 4 Prefilter Mounting Screw Location fan c 3 17 3 5 Switch Fuse Assembly Mounting Screw location tide 3 19 3 6 Spin Motor Mounting Plate Location 3 19 3 7 Filter Mounting Screw Location 3 20 3 8 Actuator Motor Leads 3 22 3 9 Shutter Mask 5 3 23 3 10 Block Screw Seven Be Aah En EE
55. ASSEMBLY SPIN MOTOR START RELAY FIXED DISC SECTOR TRANSDUCER Figure 1 3 BLOWER ASSEMBLY POWER SUPPLY PCB Disc Drive Bottom View SM 2020 1 5 SM 2020 Disc Storage Unit Table 1 2 Specifications t Parameter Characteristics ACCESS TIMES Including Head Settling 20 milliseconds track to track 35 milliseconds average random move 12 5 milliseconds average rotation delay RECORDING TECHNOLOGY bit density 2200 bits inch innermost track double frequency 1 56 M bits seconds nominal 3 12 M Hz second nominal recording format data transfer rate clock frequency 640 nanoseconds nominal 1 500 rpm 14 inch 4 bit cell time disc rotation speed disc diameter number of heads DRIVE POWER REQUIREMENTS AC 115 volts 10 60 Hz 220 volts 10 50 Hz 200 Watts Continuous I I ACCESS MECHANISM Actuator electromagnetic rotary motor Positioner optical ENVIRONMENT Temperature 10 C to 30 C 50 F to 85 F 15 C to 71 C 5 F to 160 F operating non operating power off Humidity without condensation 8 to 80 0 to 95 forced room air ambient at installed location 40 CFM ducted 10 000 feet maximum operating non operating power off cooling air circulation altitude GENERAL
56. CCESS READY SET CYLINDER DRIVE SELECT MULTIPLE HEADS SELECTED WRITE GATE DOUBLE FREQUENCY DATA SELECT FIXED DISC dike AND SELECT LOWER H START STOP AND ARRIVAL STATUS FUNCTION re READ GATE READ DATA READ FUNCTION READ po m POWER SAFE enj DC VOLTAGES SPIN MOTOR AC TO OTHER FUNCTIONS SPIN MOTOR 70 SPIN SPEED FIXED DISC SECTOR SPIN STOPPED SECTOR AND SPEED SPIN STOPPED FIXED DISC INDEX DETECTION REMOVABLE DISC SECTOR FUNCTION FIXED DISC NOTCH DETECTOR REMOVABLE DISC_INDEX REMOVABLE DISC NOTCH DETECTOR 0202 WS arun e38e1o3g 2514 Disc Storage Unit 5 2020 Data is read from a disc by having the carriage moved so the read write head is positioned over the correct track then selecting the appropriate head to start reading at the beginning of the sector containing the required data The read signal is converted read data Normal shut down procedure is to set the cartridge switch to CARTRIDGE UNLOCK wait for the door to be unlocked remove the disc cartridge close the door and set the front panel switch to POWER OFF During this sequence the Start Stop and Status Function causes the Head Positioning Function to provide actuator current which drives the carriage to home position When the Sector and Speed Detection function determines that the discs are spinning at less than 2 of normal speed the Start Stop and Status Function unlocks
57. CK 1 CENTER 2 4 224 MILLION DATA 1 056 MILLION DATA BYTES ND BYTES PER DISC 2 112 MILLION DATA BYTES PER DISC Figure 1 4 Disc Organization 1 10 Disc Storage Unit SM 2020 CARTRIDGE UPPER HALF HEAD ENTRY DOOR CLAMP RING SECTOR RING DISK ADAPTER ASSEMBLY CARTRIDGE LOWER HALF HEAD ACCESS ARE Figure 1 5 Disc Cartridge Exploded View in the sector ring the forty eighth sector is not identified by a notch but an early notch between the forty seventh and the first sectors signifies that it is the last sector The early notch is the index notch The disc itself is a 14 inch diameter disc of aluminum with an oxide coating on each side The oxide coating is tapered so the thickness varies from about 300 microns thick at the edge to about 200 microns thick near the center clamp ring When a data processing system includes more than one disc drive unit the drives and discs are numbered sequentially from 0 The removable discs are always even numbered 0 in drive 0 2 in drive 1 4 in drive 2 and the fixed discs are odd numbered 1 in drive 0 3 in drive 1 5 in drive 2 1 11 SM 2020 Disc Storage Unit The functions of the drive may be divided into 1 positioning the read write heads over a specific radial location over under the discs a track or cylinder 2 identifying the specific part of a track a sector passing under the heads at a particular time 3 magnetically recording writin
58. CONTROLLER DISC CONTROLLER CABLE XCYAO 1 XCYA2 XCYA3 XCYM 6 XCYA7 XCYA8 J1 J2 1 5 R 5 U 8 4 3 7 DRIVE CONTROL LOGIC ADDRESS BUS 1 ADDRESS BUS 2 ADDRESS BUS 4 ADDRESS BUS 8 ADDRESS BUS 16 ADDRESS BUS 32 ADDRESS BUS 64 ADDRESS BUS 128 ADDRESS BUS 256 T CYL BIT 1 P1 TP4 CYL BIT 2 TP2 CYL BIT 44 INVERTERS m TP5 CYL 8 E MMC IEEE WIRE REGISTER ANDED CYL REG DEC OF 3 35 TP7 g INVERTERS CYL BIT 32 ee SINNE FIG 3 35 DR FWD TO ZERO CYL BIT 64 FIG 3 36 LOAD CYL REG CYL BIT 128 TP6 FIG 3 35 INITIALIZATION OP F ie E 1 DIFF 1 NEN 7 22 DIFF 2 Pr kl DIFF 4 FT ME EE Ms DIFF 8 DIFF 16 ADDERS FEE EE NENNEN fee ee D DIFF 0 pig ee l ba ke NE UNCTIO DRIVE ea eee eee ae e cour om e FIG 3 37 PRESENT tole FORWARD FIG 3 35 08 HOME OP COUNTER D DRIVE FORWARD DIFF 32 COUNT UP FIG 3 37 CYL ADDERS CARRY BORROM DIFF 128 2 ADDERS BORROW BORROW F R LATCH FIG 3 35 INITIALIZATION OP T CYL BIT 1 P1 TP4 CYL BIT 2 2 CYL BIT 4 TPS CYL BIT 8 TP3 CYL 16 TP7 B CYL BIT 32 TP8 CYL BIT 64 TP9 ERTERS WIRE ANDED CYLINDER CYL REG DEC O REGISTER FIG 3 35 INVERTERS DR FWD TO ZERO
59. D CONTROLLER SENDS READ GATE MORE THAN ONE HEAD SELECTED WRITE OR ERASE GATE ACTIVE NEXT SECTOR REQUIRED CONTINUE PROCESS READ SIGNAL TO GET RAW DATA MAKE DRIVE READY AND CONTI ACCESS READY INACTIVATES INACTIVE SYNCHRONIZE READ GATE VFO TO DATA RATE MANUAL INTERVENTION DRIVE READY GENERATE COMMAND FROM SYNCHRONIZED READ CLOCK CONTROLLER RECONSTRUCT SERIAL BINARY READ DATA SEND READ CLOCK AND READ DATA TO CONTROLLER Figure 3 40 Read Function Sheet 1 3 68 Disc Storage Unit DRIVE CONTROL LOGIC SELECT READ GATE DELAYED READ GATE READ WRITE SELECT HEAD 0 SELECT HEAD 1 DISC CONTROLLER CABLE READ LIMITER XDSEL SELECT FIXED DISC HEAD READ ZERO SELECTION SELECTION SIGNAL CROSSING RAW DATA DECODER CIRCUITS CONDITIONING DETECTOR XHSEL SELECT LOWER HEAD SELECT HEAD 2 READ LIMITER SELECT HEAD 3 DMA DISC CONTROLLER XRGT READ GATE D SELECT READ INTERFACE GATE SELECT READ TP16 GATE XDRS Bue Al LOGIC SELECT READ GATE DELAYED READ GATE SELECT HEAD 0 READ LIMITER 15 ie SELECT HEAD 1 HEAD READ ZERO R M DAT SELECTION SELECTION SIGNAL CROSSING DECODER CIRCUITS CONDITIONING DETECTOR EAD gt SELECT HEAD 2 READ LIMITER SELECT HEAD
60. Figure 1 6 Comparison of Sizes Disc to Head Separation and Contaminants Disc Storage Unit SM 2020 Figure 1 7 illustrates the relationship of the drive functions to the DMA Disc Controller to the discs and to each other When the disc drive unit is in a cabinet the back panel power switch is normally left on all the time The normal startup sequence is to verify that the front panel cartridge switch is in the CARTRIDGE UNLOCK position then set the front panel power switch to POWER ON As soon as the voltages are available the CARTRIDGE UNLOCK indicator lights and the front door is unlocked so it may be opened and a cartridge inserted With the door closed and a removable disc cartridge in place the cartridge switch is set to the CARTRIDGE LOCK position The spin motor starts the discs and blower rotating The blower forces clean air across the disc surfaces to remove contaminants then out to cool the electronic circuits After dc power becomes safe the Head Positioning Function supplies a reverse drive current to the actuator until the discs are spinning faster than 70 of their nominal speed For about the first minute after the discs start spinning the Start Stop and Status Function keeps the carriage at the home position Then this function provides the control to load the heads to track 0 When the carriage is positioned at track 0 and there are no faults in the drive READY is lighted The status signals sent to the controller indi
61. GE POSITION CARRIAGE AT HOME NO YES HI NO QVEI SUI PUSH SET SWITCH TO AGAIN CRASH CARTRIDGE LOCK CHECK H PER PRE OBSERVE CARRIAGE MOTION Hi DAM CARR IAGE MOVES 2 No FI VERIFY THAT DISC DRIVE READY LIGHTS WITHIN 90 SECONDS FROM CARTRIDGE LOCK REP CARTRIDGE LOCK Figure 3 43 Tro VERIFY POWER OFF CARTRIDGE UNLOCK SET FRONT PANEL POWER SWITCH TO POWER ON YES REPLACE LAMP ISOLATE OPEN ITTOM IS 15 20 VAC REPLACE E3 E5 ON CR2 OR POWER PS SUPPLY CHECK AC VOLTAGE ON POWER TRANSFORMER ISOLATE AND REPLACE DEFECTIVE PART IN AC INPUT CIRCUIT NO YES CARTRIDGE UNLOCK LIGHTS CARTRIDGE UNLOCK LAMP GOOD NO YES REMOVE TOP COVER 1S YES 0 To AT B3 1 NO REPAIR REPLACE DRIVE CONTROL LOGIC CARD ISOLATE REPAIR OPEN OR FAULTY SOLENOID ISOLATE OPEN IN 15 RAW CIRCUIT OPEN DOOR INSEAT CARTRIDGE DOOR UNLOCKED DE NO REMOVE TOP COVER IS 15V RAW YES AT CARTRIDGE SOLENOID NO VERIFY B3 IS SECURE IF OK REMOVE BOTTOM COVER Is F4 ON POWER YES SUPPLY NO REPLACE FUSE NO YES ISOLATE SHORT SM 2020 YES MOTION ERRATIC YES NO 3 72 CLOSE DOOR REMOVE TOP COVER OBSERVE CARRIAGE POSITION CARRIAGE AT HOME YES
62. H H NFP NWP o A Ww I SM 2020 Parts List for VFO Circuit Card figure 4 22 continued Reference Designator Part No Part Name R66 10101 Resistor 7 10K 5 1 4w R67 10066 Resistor 07 5 1K 5 1 4w U2 U5 U5 U6 U7 2585 Integrated Circuit CA3046 U15 U19 U20 17102 Integrated Circuit 74H00 U14 17012 Integrated Circuit 74107 U15 17013 Integrated Circuit 7476 U17 U18 17103 Integrated Circuit 74H10 U21 U25 U31 U32 17002 Integrated Circuit 7400 U22 17055 Integrated Circuit 9602 123 1033 034 17003 Integrated Circuit 7410 U24 17001 Integrated Circuit 7404 026 027 17055 Integrated Circuit 74193 U28 U29 17010 Integrated Circuit 7442 U30 17009 Integrated Circuit 7402 ne 5 4 Wom aN e S 7 Bg q 2 oors 9 xa Gan 55555 BEE a Figure 4 22 VFO 73560 4 38 Disc Storage Unit Quantity PNR Ew Disc Storage Unit Parts List for Read Write Circuit Card figure Reference Designator C1 C9 C10 C11 C12 C2 C14 C15 C3 C4 c5 C6 C7 C8 C13 C22 C23 25 26 27 28 31 32 16 36 C17 C19 C18 C20 C21 C29 C30 C33 C34 C37 C38 C35 CR1 thru CR21 CR22 CR23 11 L2 L5 04 15 L6 L7 Q1 Q2 05 04 07 08 05 06 09 010 011 019 020 021 022 012 thru 016 028 Q17 Q18 Q29 thru 034 Q23 thru Q26 Q27 R2
63. LECTED HEAD 1 SELECTED HEAD 2 SELECTED HEAD 3 SELECTED WRITE CURRENT SELECT HEAD 0 ERASE CURRENT READ SIGNAL DOUBLE FREQUENCY WRITE DATA SELECT WRITE GATE POWER SAFE SELECT WRITE GATE EE SUBTRACT WRITE CURRENT READ LOGIC SELECT ERASE GATE WRITE 6 AMPLIFIER SELECT HEAD 3 SELECT HEAD 2 WRITE CURRENT SELECT HEAD 1 ERASE CURRENT READ SIGNAL READ WRITE AMPLIFIER SELECT HEAD 1 SELECT HEAD 0 SELECT READ GATE WRITE CURRENT SELECT HEAD 2 ERASE CURRENT READ SIGNAL TRANSDUCER SIGNAL REMOVABLE DISC WRITE CURRENT SELECT HEAD 3 ERASE CURRENT READ SIGNAL TRANSDUCER SIGNAL FIXED DISC Figure 3 41 Interconnection Diagram 3 70 Disc Storage Unit 15V UNREG 4 m 93 819 15V REG 1 144002 15V UNREG 295195 4 0 1 R15 R16 amp 2 100 470 15V RAW CRIL 15V REG 1N52318 ix 15V UNREG 15V DRIVE HOME v2 3 NON LM723 me CR2 MDASBO 3 R50 TO POWER TRANSFORMER SECONDARY 923 T 2N4401 V 07 Y VS 284401 2s 45V REF ES 1N3064 JON REF 5V REF CRI2 me 15V UNREG 2N5195 m R60 0 25 CR3 1N4742A A 2N5982 a4 2N4403 2N4403 15V REG 913 2N5985 15V REG R62 LH 0 25 i 1 15V UNREG net CRI UK 15V UNREG a TO POWER P TRANSFORMER SECONDARY T 1N52328 5 6V SV OFF 1 1 R67
64. Motor Assembly figure 4 8 Reference No WOON ANA WN 4 16 Part Number 19010 73118 13330 73051 73448 73224 73045 73046 73236 73034 73037 73318 73225 73226 73223 73631 13824 Part Name Screw Retainer shaft Screw Retainer spring Back plate double Clip Finger spring Bearing Actuator motor Shaft actuator Bearing Screw double actuator Cap Brush Holder brush Cable assembly Screw set Disc Storage Unit Quantity HH HP F 29 DN Disc Storage Unit SM 2020 Figure 4 8 Actuator Motor Assembly 74226 SM 2020 Parts List for Chassis Assembly Bottom View figure 4 9 Reference No Part Number 1 B73408 2 D73633 3 73635 4 73606 5 13303 6 14016 7 13656 8 74210 9 15802 10 13349 11 73663 12 13316 13 13653 14 14016 15 13835 16 A73409 17 60411 18 13351 19 A73120 20 73622 21 74303 22 A73633 23 B73633 24 C73633 25 13449 26 74304 4 18 Part Name Disc spindle assembly Wire assembly Cable assembly Sector transducer Screw Lockwasher Screw Panel assembly switch Cable tie Screw Air filter Screw Screw Washer Screw set Sector pulley Belt flat Screw Blower assembly Cable assembly Bracket circuit card mounting Wire assembly Wire assembly Wire assembly Screw Bracket circuit card mounting Disc Storage Unit Quantity NPR EP RP EA IO IPS OI GIL
65. Number 1 74226 2 13314 3 73301 4 73121 5 14015 6 A B 73664 7 18570 8 73115 9 14104 10 14015 11 73122 12 13644 13 73116 14 73118 15 19010 16 13317 17 73205 18 73111 19 19201 20 18460 21 73105 22 73665 23 73008 24 73012 25 73117 26 73024 27 73021 28 73023 29 73113 30 13414 31 13316 32 73206 33 73108 34 73207 35 73666 36 14014 37 73208 38 73229 39 73030 40 73138 41 73231 42 74227 43 74228 44 18560 45 0546 46 14013 47 14102 48 14103 49 73010 50 73446 51 73106 52 74403 53 13619 Part Name Actuator motor Screw Track indicator plate Rail short Washer lock Crash stop Stop Clamp Nut Washer lock Rail long Screw Crank Retainer shaft Screw Screw Bracket adjusting Bearing carrier Dowel pin Groove pin Carriage Limiter Spring Washer Spring plate Bearing Link Spring Screw Screw Screw Bracket plate mounting Screw adjusting Plate adjusting Screw Washer lock Clamp Clamp Shutter assembly Pin bearing Bearing actuator Cap Spacer Washer wave Bearing Washer lock Nut Nut Transducer assembly Clamp cable Frame Washer Screw Disc Storage Unit Quantity FA Gd G Q Q Q Qa I d gt E GS dS PO ES AN 00 ES NEF OS O gt N S SM 2020 Disc Storage Unit Actuator Assembly 73020 Figure 4 7 4 15 SM 2020 Parts List for Actuator
66. P PROGRAM ALIGNMENT WATCH CARRIAGE MOTION CHECK DIFF PULSES CARRIAGE MOVES PER YES PROGRAM DIFF PULSES PER NO PROGRAM YES REPLACE DRIVE CONTROL LOGIC CIRCUIT REPLACE CARD SERVO 2 CIRCUIT CARD AS SOON AS SWITCH IS THROWN STAYS ON 1 3 SEC AFTER SWITCH IS THROWN RUN DISC DIAGNOSTIC lt gt YES CONTIN UOUS DATA ERRORS RANDOM ERRORS SET TO SPECIFIC ONLY HEAD ONE NO HEAD ONLY WATCH CARRIAGE AND FRONT PANEL INDICATORS YES ONLY YES CERTAIN TRACKS CHECK READ CHECK HEAD FOR REPLACE 1 AMPLITUDE CONTAMINATION REPLACE DISC NO DRIVE CONTROL _ LOGIC CARD VERIFY AMPLITUDE HEAD SIGNAL TO HEAD ACCEPTABLE DIRTY REPLACE HEAD CARRIAGE OR R W CARD NO TO REAR CRASH S lt STOP REPLACE CLEAN HEAD R W CARD OR PER HEAD PREVENTIVE MAINTENANCE CHECK HEAD 1 ALIGNMENT YES SET TO OUT REPAIR CARTRIDGE UNLOCK TOO SOON POWER No SUPPLY AND YES lt REMOVE CARTRIDGE PERFORM HEAD ALIGNMENT PROCEDURE CHECK FOR HIGH READ GATE AT TP16 ON DRIVE CONTROL LOGIC REPLACE COVERS AND SECURE DRIVE VES OF GROUND IN MOTOR SWITCH ON CIRCUIT ISOLATE SOURCE READ NO G TE OK REPLACE YES AC POWER DELAY RELAY CHECK READ DATA LOW LATCH AT Al R REPAIR NO REPLACE POWER SUPPLY PULSE AT J1 P INTERFACE
67. PECIAL CAUTIONS Most procedures of this section require that the drive be exposed by extending the drive from the cabinet and removing the top and back covers Operating in this manner for prolonged periods of time can result in damage to the read write heads discs carriage and positioner motor if care is not exercised to keep all foreign matter out of these areas Although the drive is equipped with a clean air filtration system when operating without covers the read write heads should be checked for contamination at hourly intervals and cleaned if necessary The positioner motor has a strong magnetic field which will magnetize a wrist watch if worn while working on the drive Also if you should drop any hardware in this area while servicing the drive it is likely that they will be attracted to the magnet During removal and replacement procedures do not place small items such as screws SM 2020 Disc Storage Unit and washers on the drive base as they may accidentally fall through the air door into the fixed disc housing where they may cause catastrophic failure later Do not touch the fixed disc exposed surface at any time 3 3 DETAILED FUNCTIONAL DESCRIPTION The circuits in the disc drive unit are divided into six functional groups 1 The Power Function figure 3 34 includes the distribution of ac input power to the spin motor and the power transformer the generation and distribution of dc voltages the generation of the motor switch
68. Q13 Q23 Q14 Q15 Q16 Q21 Q22 Q24 R1 R16 R2 R48 R77 R3 R8 R28 R29 R63 R67 R74 R75 R9 R15 R49 R10 R11 R46 R47 R50 R51 R56 R57 R12 R13 R14 R17 4 42 Part No 73750 73751 12812 12801 16962 12534 16924 16922 16966 12818 2461 13025 13005 13031 13007 13009 16102 16106 18703 18920 12907 12920 12910 12904 12909 12921 12937 12947 12929 10041 10037 10049 10930 11148 16635 10029 10025 10045 10056 10055 13207 10066 11126 Part Name Power supply assembly Power supply circuit board Capacitor CER 0 1uf 50V Capacitor CER 0 01uf 50V Capacitor 30D 100uf 25V Capacitor 192P 0 001uf 200V Capacitor 30D 10uf SOV Capacitor 30D 100uf 50V Capacitor 30D 50uf 25V Capacitor CER 1 0uf 50V Bridge rectifier Diode 1N4742A Diode 1N3064 12V 5 Diode 1N5232B 5 6V 5 Diode 1N40002 Diode 1N5231B 5 1V 5 Fuse 5 amp Fuse 1 amp Fuse 4 amp Relay 603 12V Transistor 2N3055 Transistor 2N5195 Transistor 2N4403 Transistor 2N2904 Transistor 2N4401 Transistor 2N5192 Transistor 2N4441 SCR Transistor 2N5982 Transistor 2N5303 Resistor 7 470 ohm 5 1 4w Resistor RCO7 330 ohm 5 1 4w Resistor RCO7 1K 5 1 4w se Resistor RNSSD 200 ohm 1 1 8w Resistor RN55D 976 ohm 1 1 8w Resistor RS 10 0 5 ohm 3 13w Resistor RC07 150 ohm 5 1 4w Resistor 07 100 ohm 5 1 4w Resistor RC07 680 ohm
69. R3 R4 R36 R44 RS R6 R7 R8 R10 R11 R15 R16 R18 thru R25 R101 R9 R24 thru R29 R102 R106 R107 R12 R13 R14 R49 R17 R30 R31 R32 R33 R34 R35 R37 R39 R38 R40 R41 R42 R43 R45 R46 R47 R48 R100 RSO R51 thru R54 Part No 73460 12631 12812 12505 12627 12814 60008 12603 12619 12801 17337 17329 13005 13027 13025 14808 18320 12904 12914 12910 12909 2411 12943 12921 10033 10032 10106 10044 10049 10041 12148 10906 11054 10065 10070 10064 10068 10072 11137 10930 10001 10430 10051 Read Write Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor 4 23 Part Name circuit card DM 220pf 500V CER 0 1uf 50V 192P 0 0047uf 80V DM 150pf 500V CER 0 22uf 50V DM 560pf 300V DM 15pf 500V DM 68pf 500V CER 0 01uf 50V 150D 10uf 20V 150D 2 2uf 20V Diode 1N3064 Diode 1N4735A 6 2V Diode 1N4742A 12V 5 5 ge Inductor 47uh Inductor 100uh Transistor Transistor Transistor Transistor Transistor Transistor Transistor Resistor 7 220 ohm 5 Resistor RC07 200 Resistor RCO7 16K 5 Resistor 7 620 ohm 5 Resistor RCO7 1K 5 2N2904 2N4924 2N4403 2N4401 MPS918 2N5555 2N5192 1 4w ohm 5 1 4w 1 4w 1 4w 1 4w Resistor RCQ7 470 ohm 5 1 4w Resistor RN650 549 ohm 1 RNSSD 20 ohm 1 R
70. RIVE FORWARD FIG 3 35 SHAPED ERROR HI RVDR DIFF 0 FIG 3 36 FIG 3 36 DRIVE FORMARD 041 9 5 MSEC DELAY ARRIVAL LZEN L0 F F SARZN P3 FIG 3 35 Figure 3 37 I 3 62 VERSE DRIVE RIVAL ZONE ACK 000 ME POSITION NEAR ZONE ENABLE RWARD ENABLE VERSE ENABLE RWARD DRIVE SERVO NUMBER ONE SM 2020 DRIVE 218 CURRENT CONTROL SUPPLY LOGIC M REFERENCE RECTIFIER LED DRIVE AND FILTER ur FIG 3 36 2HE 0 10 A B A B te oe 1 BEFORE A B HI LOGIC A B BUFFER A B HU BEFORE COUNT UP PULSES 3 36 B4 LIN SIG TP INVERTER gt LOGIC 0 8 BUFFER 16 DIFF 0 HI A B HI FDDR DRIVE FORWARD H1 10 DIFF 0 10 A B m FIG 3 36 18 13 HI FIG 3 36 5 0 DRIVE FORWARD L0 FIG 3 36 5 MSEC DELAY LZEN 10 ARRIVAL NULL LOGIC HI DETECTOR BUFFER ARZN H1 TACH GEN Disc Storage Unit SHUTTER ASSEMBLY SERVO NUMBER ONE TP5 12 FORWARD SHAPED ERROR Cs T SHAPED ERROR SWITCH A B HI RVDR A B 10 LO b DIFF 0 L0 LINEAR SWITCH REVERSE SWITCH LINEAR TACH Figure 3 37 Position Control Circuits Sheet 1 3 62 DRIVE POSITION 0000 Disc Storage Unit SERVO NUMBER TWO 3 current 3 INITIALIZATION 0P FIG 3 35 FEEDBACK CU
71. ROWN STAYS ON 1 3 SEC AFTER SWITCH IS THROWN RUN DISC DIAGNOSTIC SET TO POWER OFF WATCH CARRIAGE AND FRONT PANEL INDICATORS REPLACE DRIVE CONTROL LOGIC CARD REPLACE DISC YES OUT REPAIR CARTRIDGE UNLOCK YES lt SOON POWER SUPPLY REMOVE CARTRIDGE REPLACE COVERS AND SECURE DRIVE ISOLATE SOURCE OF GROUND IN MOTOR SWITCH ON CIRCUIT YES YES REPLACE AC POWER DELAY RELAY REPAIR REPLACE POWER SUPPLY CONTIN UOUS DATA RANDOM ERR ERRORS YES SPECIFIC HEAD ONLY d NO ONLY CERTAIN TRACKS YES YES CHECK READ AMPLITUDE NO VERIFY SIGNAL TO HEAD AMPLITUDE ACCEPTABLE YES REPLACE HEAD OR R W CARD NO REPLACE R W CARD OR HEAD LOW PULSE AT J1 P INTERFACE CHECK CONTROLLER AND CABLE CONNECTORS REPLACE DRIVE CONTROL LOGIC CARD HEADS POSITIONED OVER DISC PUSH CARRIAGE AGAINST REAR CRASH STOP SET TO CHECK ACTUATOR RAILS FOR CLEANLINESS RAILS DIRTY OR YES OBSTRUCTED ih CLEAN ENTER DHO RAILS PER SEEK LOOP PROGRAM PRAIS PER CHECK AMPLITUDE AND PHASE OF AND B PER TABLE 3 3 AMPL I TUDE ACCEPTABLE m YES ALIGN OPTICAL VERIFY THAT HMTP TRANSDUCER A4 S SWINGS TO 2V AT TRACK 000 PERFORM OPTICAL TRANS ENTER TRACK DUCER SHUTTER STE
72. RRENT FEEDBACK AE LZEN 1 8 F B RESET LINEAR ENABLE SWITCH A B FORWARD LATCH SET RATE TACH REVERSE LATCH SET 18 4 16 15 GENERATOR D HON ACCESS TIME FORWARD PREAMP DRIVE 35 MSEC LINEAR ZONE ACCESS TIME OVERSHOOT R77 REVERSE PREAMP DRIVE 1 TRACK OVERSHOOT MAX 70 SPIN SPEED FIG 3 38 POSITION 21 FORWARD RATE TACH SMETCR TACH DR CURRENT FEEDBACK RATE TACH REVERSE RATE TACH RVEN SWITCH LINEAR SWITCH T e 50 3 TP1 ENABLE RESET SERVO ENABLE RESET SERVO ACCESS TIME 35 MSEC MAX LINEAR ZONE 1 TRACK OVERSHOOT MAX FIG 3 35 INITIALIZATION OP D 418 7 8 CURRENT FEEDBACK AON TERR SWITCH 1 8 F B LINEAR SWITCH FORWARD LATCH SET RATE TACH GENERATOR REVERSE LATCH SET FORWARD PREAMP DRIVE ACCESS TIME OVERSHOOT R77 REVERSE PREAMP DRIVE FORWARD RATE TACH SWITCH REVERSE RATE TACH SWITCH LINEAR TACH SWITCH A3 CONTROL 70 SPIN FIG 3 38 SPEED TACH DR CURRENT FEEDBACK POWER SUPPLY FIG 3 34 15V F5 FORWARD DRIVE REVERSE DRIVE FIG 3 34 FIG 3 34 DRIVE HOME 15V UNREG FIG 3 34 Figure 3 37 SM 2020 HEAD PROTECTION HEAD POSITIONING ACTUA
73. S AC POWER DELAY RELAY DEENERGIZED 5 TO POWER ON AND CARTRIDGE UNLOCK DARK DOOR LOCKED 2 CARRIAGE MOVES TO REAR CRASH STOP Disc Storage Unit INCORRECT SET TO POWER OFF MOTOR SWITCH ON SETS LOAD HEADS LOW DRIVE READY INACTIVE DRIVE READY DARK DRIVE HOME OP SET LOW INITIALIZATION LATCH SET REGISTERS SET FOR TRACK 000 DRIVE HOME OP SUBSTITUTED FOR BIT 32 OF PRESENT CYLIN DER ADDRESS REVERSE DRIVE TO ACTUATOR TRACK 000 DETECTED d YES RESET INITIALIZE LATCH WAIT WAIT CE DELAY OVER POWER ON AND CARTRIDGE LOCK DARK DOOR LOCKED Figure 3 35 Start Stop and Status Function Sheet 1 Disc Storage Unit DRIVE CONTROL LOGIC UNLOCK CARTRIDGE HI FRONT PANEL CARTRIDGE MOTOR SWITCH ON HI FIG 3 SWITCH FIG 3 34 INTERFACE 22 FIG 3 38 6 70 SPIN SPEED 7 SPIN STOPPED POWER SUPPLY FIG 3 34 BECOMES SHAPED ERROR FIG 3 37 FORWARD DRIVE FIG 3 37 BIT 16 SET CYLINDER REGISTER TO ZEROES SERVO NUMBER ONE DRIVE HOME OP 1 SET LO BIT 32 BECOMES SHAPED SEEK INCOMPLETE HI SHUTTER TRACK 000 3 SET LO ERROR FIG 3 37 ASSEMBLY DETECTOR CYL REG DEC OF REVERSE DRIVE FIG 3 36 4 SET Lo SET PRESENT R YLINDER FIG 3 37 ARRIVAL
74. SERVICE MANUAL for the Disc Storage Unit and Controller Dosic Four corporation D SM 2020 SERVICE MANUAL for DISC STORAGE UNIT November 1 1974 att basic Four corporation BD A Subsidiary of Management Assistance Inc MAI 1335 South Claudina Street Anaheim California 92805 Copyright 1974 Basic Four Corporation Printed in U S A ii basic PROPRIETARY INFORMATION The information contained herein is proprietary to and considered a trade secret of Basic Four Corporation and shall not be reproduced in whole or part without the written authorization of Basic Four Corporation d are registered trademarks of BASIC FOUR CORPORATION Disc Storage Unit SM 2020 List of Effective Pages Revision Page Date 1 1 thru 1 15 Original 2 1 thru 2 2 Original 3 1 thru 3 73 Original 4 1 thru 4 45 Original Disc Storage Unit 5 2020 TABLE OF CONTENTS SECTION 1 GENERAL DESCRIPTION 1 1 Scope SSG S 1 1 1 2 Purpose qr 1 2 1 3 Physical Description Huc 1 3 1 4 Functional Description e e s s so 1 9 SECTION 2 OPERATION 2 1 Switches 2 1 2 1 1 1 Power Switch d fe KNE GS 2 1 2 1 2 Front Panel Power Switch 2 s 2 1 2 1 3 Cartridge Switch 2 1 2 2 Indicators 3 2 1 2 2 1 Power On
75. Switch Panel Assembly figure 4 15 Reference No Part Number Part Name Quantity 1 73210 Control panel 1 2 60241 Lamp assembly 1 3 60242 Lamp assembly 2 4 60750 Lamp 3 5 18600 Switch rocker 2 6 15801 Cable tie 9 7 23390 Arc suppressor 1 8 14501 Tubing A R 9 73200 Switch panel 1 Figure 4 15 Switch Panel Assembly 73250 4 26 Disc Storage Unit Parts List for Sector Transducer Assembly figure 4 16 Reference No Part Number Part Name 1 18381 Connector 2 60379 Contact 3 18390 Plug 4 60377 Cable 5 73165 Sector sensor COLLECTOR WHITE ANODE GRAY CATHODE VIOLET VIOLET DOT Figure 4 16 Sector Transducer Assembly 73606 SM 2020 Quantity HEN ad 4 27 SM 2020 Disc Storage Unit Parts List for Bottom Panel figure 4 17 Reference No Part Number Part Name Quantity 1 15807 Cable tie 3 2 15802 Cable tie 9 3 73613 Cable 1 4 24350 Circuit breaker 1 5 22390 Arc suppressor 1 6 15830 Cable clamp 1 7 15845 Clamp 1 8 22580 Capacitor motor start 1 ORANGE FROM TRANSFORMER BROWN NOTE CABLE ROUTING SHOWN IF FOR REFERENCE ONLY GREEN BLACK FROM TRANSFORMER Via S GREEN WIRE FROM LINE CORD GREEN FROM SPIN MTR CASE REF YELLOW AND BLACK FROM SPIN MTR TO 1 7 RED FROM SPIN MTR p n WIRE FROM SWITCH FUSE ASSEMBLY ol dB PACK FOM ASSAY BROWN RED WIRE TO TERMINAL 9 OF POWER OFF DELAY RELAY
76. TIVE 2 YES SET ARRIVAL FLIP FLOP GENERATE ACCESS READY DRIVE CONTROL TRANSFERRED DIFFERENCE CON VERTED TO AMP LITUDE OF SHAPED ERROR SIGNAL GENERATE SEEK INCOMPLETE IS CARRIAGE MOVING FORWARD TRIGGER 4u S S ON LEADING EDGE OF A B WHILE A B IS ASSERTED TRIGGER 4u S S ON TRAILING EDGE OF A B WHILE A B IS ASSERTED TO CONTROLLER GENERATE COUNT UP PULSE GENERATE COUNT DOWN PULSE INCREMENT PRESENT CYLINDER ADDRESS BY ONE DECREMENT PRESENT CYLINDER ADDRESS BY ONE COMPARE PRESENT CYLINDER ADDRESS WITH NEW ADDRESS 200 MSEC DELAY OVER e CARRIAGE MOVES 1 25 MILES TOWARD TRACK CENTER LINEAR ZONE ENABLE IS ACTIVE FOR 1 25 MILS EITHER SIDE OF TRACK CENTER TRACK CENTER DEFINED BY LINEAR SIGNAL CROSSING ZERO ARRIVAL ZONE IS ACTIVE FOR 0 56 MIL EITHER SIDE OF TRACK CENTER A B COUNT PULSE DIFF 0 FWD DRIVE LINEAR ZONE ENABLE ARRIVAL ZONE 1 94 MILS 2 5 MILS 5 0 MILS SM 2020 FLOW AND TIMING DIAGRAMS FOR HEAD POSITIONING FUNCTION SERVO TIMING l f l f L dole dicc 1 25 MILS 0 69 MIL 0 56 MIL ARRIVAL LINEAR TRACK TRACK CENTER ZONE ZONE WIDTH DIRECTION SENSE AND COUNT CONTROL A B DD l J kolera VF qc A B REV f 1 COUNT PULSE FWD 1 1 1 1 COUNT PULSE REV J 1 ef n
77. TOR CURRENT FEEDBACK Position Control Circuits Sheet 2 3 63 NOTCH PULSES SECTOR INDEX TRANSDUCER DELAY 730 uSEC DELAY 5 uSEC INDEX SECTOR 48 PULSE POSITION 5 uSEC SECTOR PULSE SECTOR CONTENT 46 830 uSEC SM 2020 SECTOR AND INDEX PULSE TIMING 47 620 USEC INDEX Disc Storage Unit 1040 uSEC U2 6 L En 110 10 U14 9 mp Er 46 830 uSEC 47 MEE 110 DATA BYTES 30 PREAMBLE ne 10 BYTES POSTAMBLE POSTAMBLE CONTAINS SECTOR NUMBER TRACK NUMBER AND OTHER HOUSEKEEPING INFORMATION 830 uSEC ADJUSTABLE FROM 18 180 uSEC Figure 3 38 48 1 830 uSEC TYPICAL IS 25 30 uSEC Sector and Speed Detection Function Sheet 1 SM 2020 INTERFACE 18 180 uS R3 DRIVE CONTROL LOGIC DRIVE DMA DISC B7 AS 2 9 CONTROL CONTROLLER REMOVABLE DISC DISC REMOVABLE REMOVABLE 47 SECTOR PULSES REMOVABLE CONTROLLER 1 NOTCH DETECTED m REANA LOGIC 3 CONTR 4 TRANSDUCER TRANSDUCER DELAY 48TH SECTOR PULSE B16 014 9 PULSE 48 POSITION REMOVABLE INDEX B17 70 SPIN SPEED FIXED SECTOR FIXED DISC NOTCH DETECTED FIXED DISC TRANSDUCER B12 SPIN STOPPED FIG 3 35 FIXED INDEX XIPF B13 CONTROLLER CABLE J1 3 DRIVE DMA DISC XDRSO SELECT CONTROLLER Figure 3 38 Sector and Speed Detection Function Shee
78. VABLE TRACK 000 INDEX FIXED DMA DISC HOME POSITION LED DRIVE SHUTTER SECTOR FIXED CONTROLLER SERVO F ASSEMBLY ACCESS READY 1 Nen ACCESS READY 2 A B 3 L fell R ACCESS READY 3 LINEAR SWITCH ENER SECTOR COUNT 1 LINEAR TACHOMETER pe er SECTOR COUNT 2 POSITION DRIVE L j ADDRESS ACKNOWLEDGE ADDRESS REJECT c lt X lt gt w A3 SHAPED ERROR TACHOMETER DRIVE FORWARD LATCH SET DRIVE SELECT 0 RESTORE 1 B5 B5 CURRENT FEEDBACK Sunt pe SUPPLY POWER SAFE 5 DRIVE SELECT 1 DRIVE SELECT 2 B3 B3 DRIVE SELECT 3 FRONT B MOTOR SWITCH ON DIFFERNCE 16 si offers DIFFERENCE 64 2566 sd 64 256 DIFFERENCE 128 256 2 CURRENT FEEDBACK SERVO NO 2 SERVO NO 2 gt v ACCESS READY PANEL SET CYLINDER Al Al BS ADDRESS BUS 1 READ GATE TRIGGER s REVERSE PREAMP DRIVE ADDRESS BUS 2 i READ DATA LATCH E MER ADDRESS EE READ CLOCK ADDRESS BUS 8 READ DATA 5 ADDRESS BUS 16 Y READ CLOCK ADDRESS BUS 32 ADDRESS BUS 64 LINE A2 Al Al ADDRESS BUS 128 TERMINATION RAW DATA RAW DATA X READ GATE W DELAVED READ GATE 50 VFO TEST DATA GATE ADDRESS BUS 256 DOUBLE FREQUENCY WRITE DATA READ GATE WRITE GATE SELECT FIXED DISC SELECT LOWER HEAD HEAD 0 SE
79. WER ON position and the cartridge switch in the CARTRIDGE UNLOCK position both the spin stopped and motor switch on signals are high This combination results in the 5V off signal being active low in the cartridge unlock lamp being on and in the cartridge unlock door solenoid being energized so the door may be open to remove or insert a cartridge With a cartridge in place and the door closed the motor switch on signal will go low when the cartridge switch is placed in CARTRIDGE LOCK This deactivates the 5V off signal thus enabling 5 volts to the drive logic The spin stopped signal will go low almost immediately since it is active high when the discs are rotating less than 2 of normal speed When spin stopped goes low a 64 second delay one shot is triggered This ensures that the load heads signal will remain low for a minute to allow the spin motor to come up to normal speed 3 4 Disc Storage Unit SM 2020 When the 5 volts is enabled and the load heads signal is low drive home is set active low A low drive home op signal sets the initialize latch which sets the cylinder register to all zeroes and the present cylinder address register to all ones This configuration of the registers is for track 0 and results in a shaped error signal of zero so the drive home op signal is substituted for bit 32 of the present cylinder address register The drive home op signal then becomes a shaped error signal equivalent to a real situation w
80. able disc heads and the fixed disc heads 3 16 Disc Storage Unit SM 2020 Table 3 1 Six Month Preventive Maintenance continued 16 17 18 19 Clean the removable disc sector transducer a Wrap masking tape around one hand with sticky surface exposed b Press the tape against all surfaces of the transducer figure 4 3 until all the metallic and dirt particles adhere to the tape Clean the fixed disc sector transducer a Loosen two screws securing fixed disc sector transducer figure 1 3 and slide transducer towards back of drive b Using the sticky surface of masking tape press tape against surfaces of transducer until all metallic and dust particles are removed c Replace sector transducer to original position and retighten mounting screws Clean the disc spindle area a Wrap masking tape around one hand with the sticky surface exposed b Press the tape against all areas of the spindle until all metallic and dirt particles adhere to the tape Replace the prefilter a Position drive control logic card so that access may be made to three prefilter plate mounting screws b Remove three screws securing prefilter plate to chassis Remove screen prefilter figure 3 4 PREFILTER PLATE MOUNTING SCREWS BOTTOM COVER MOUNTING SCREWS Figure 3 4 Prefilter Mounting Screw Location 3 17 SM 2020 Disc Storage Unit Table 3 1 Six Month Preventive Maintenance contin
81. age and the A B signal controls the amount of current through the led so the total effective radiation at the QA and B photodiodes is constant The output of the second amplifier is converted to a logic signal converted to a tachometer signal and monitored to detect the arrival zone The A B signal is delayed and logic then compares the A B A B and A B delayed signals to develop count down pulses when the carriage is moving forward the A B signal is high before the A B signal or to develop count up pulses when the carriage is moving back toward track 0 the A B signal is high before the A B signal The count up or count down pulses increment or decrement the present cylinder address counter until the difference 0 signal is active low When the difference 0 signal is active the next low state of the A B signal generates the linear zone enable signal which increases the amount of effect the current feedback and tach signals have on the output of the summing amplifier When the carriage is positioned near enough to the selected track for the linear zone enable signal to be active the servo loop is extremely sensitive to very small error signals thus making it possible to position the carriage so the read write heads are positioned over the center of a track that is only 0 005 inch wide Disc Storage Unit SM 2020 If during normal drive operation the disc rotational speed sho
82. al the head position control circuits develop a positioner drive current that causes the heads to be quickly and accurately positioned over the commanded cylinder of the discs track 0 or home position 4 The Sector and Speed Detection Function figure 3 38 detects notches in the fixed disc pulley and the removable disc skirt Forty seven of the notches for each disc are sector notches and the forty eighth notch is an index notch From these notch detected signals the Sector and Speed Detection Function generates signals that identify the beginning of each sector and each revolution index of the fixed and removable discs This function also generates a 70 spin speed signal when the discs are rotating fast enough for it to be safe to load the heads and a spin stopped signal to indicate that the discs are rotating at less than 2 of normal spin speed so it is safe to open the door 5 The Write Function figure 3 39 decodes the select fixed disc and select lower head signals form the controller to select one of the four read write heads and generates a bipolar write current form the double frequency write data signal when enabled by the write gate signal The Write Function also generates an erase current during the time of and 25 microseconds after 3 2 Disc Storage Unit SM 2020 the write gate signal This erase current creates a quiet gutter between recorded tracks on the disc surface The Write Function also varies the amount of wr
83. ble the appropriate cables are connected between the CPU and Disc Cabinets 3 Verify that the cable from the controller is securely attached to 1 on the Drive Control Logic card and that the terminator or cable to the next drive is securely attached to P2 on the Drive Control Logic 3 11 SPECIAL TOOLS TEST EQUIPMENT AND MATERIALS Most of the tools and test equipment required for maintenance of the drive are standard items Special tools are required only for shop maintenance Cleaning materials however are appropriate for field use 3 11 1 SPECIAL TOOLS The following special tools will be necessary Card Extender Test Hub Disc Diagnostic Cartridge Head Clamping Wrench Head Spacers Disc Storage Unit SM 2020 3 11 2 CLEANING MATERIALS The following cleaning materials will be necessary Lint free Tissue 3 4 inch X 6 inch hardwood tongue depressors 91 Isopropyl Alcohol Masking Tape Cotton Swab Lens Paper Dental Mirror 3 11 3 FIXED DISC REPLACEMENT KIT A fixed disc replacement kit is available which consists of a recording disc nylon glove and instructions for installation 3 11 4 TEST EQUIPMENT The following test equipment will be necessary Alignment Cartridge Drive Test Unit 3 12 PREVENTIVE MAINTENANCE The following preventive maintenance operations and routine checks are intended to assure reliable operation of the Disc Storage Unit Drives being operated more than 200 hours per month should hav
84. cal transducer and shutter alignment should be performed when either the optical positioning transducer or the shutter has been replaced or when positioning errors are detected This alignment procedure is to set the correct distance 3 21 SM 2020 Disc Storage Unit between the shutter assembly and the transducer block mask The correct nominal spacing is 0 005 inch The optimum shutter mask spacing is obtained by moving the shutter while observing a Lissajous pattern indicating a 90 phase difference between QA and QB NOTE It is not necessary to perform the steps to loosen the transducer block or shutter to check the trans ducer block shutter alignment Table 3 3 Optical Transducer Shutter Alignment Procedure Remarks 1 Remove cartridge remove power a Set switch to CARTRIDGE UNLOCK and extend drive to obtain access b When CARTRIDGE UNLOCK lights pull to back and bottom of drive down on receiver door and remove the cartridge then set switch to POWER OFF Set ac switch on rear panel to the OFF position 2 Remove nine screws securing bottom This permits access to disconnect panel to chassis and remove bottom actuator motor cover 3 Disconnect red lead from servo This disconnects drive current to the motor to E13 and the black lead actuator motor to E14 on power supply card figure 3 8 Figure 3 8 Actuator Motor Leads 3 22 Disc Storage Unit Table 3 3 SM 2020 Optical Transducer Shutter
85. cate that the disc drive is operational The disc drive unit is then under program control Once the drive indicates an operational status to the controller the CPU may command the drive to position the heads at an address track number The Start Stop and Status Function then causes the Track Number and Head Position comparison circuits to load the address in a register and initiate head repositioning The present head position is compared to the contents of the address register and when there is a difference the resulting shaped error signal causes an actuator current to move the carriage until it is positioned to the commanded address If the carriage is correctly repositioned in less than 200 milliseconds the status signals return drive control to the program Index and sector pulses from the Sector and Speed Detection Function are then used by the controller to select the starting sector for either a read or write operation In order to write on one of the disc surfaces the controller has to command the Write Function to select a read write head Then as the correct sector begins to pass under the read write head the controller has to send control signals to the Write Function to generate the write signal L T ueigerq BUOTJOUNH con ROLLER HEAD POSITIONING FUNCTION ADDRESS 9 LINES TRACK NUMBER AND HEAD POSITION COMPARISON SELECT DRIVE READY SELECT SEEK INCOMPLETE SELECT A
86. ce Designator Part No Part Name Quantity 01 thru U7 U9 U10 60358 Integrated circuit LM1458M 9 U8 17023 Integrated circuit SN7407 1 U11 17029 Integrated circuit SN7414 1 73591 9270 P B T 16 BRE 65 R59 GRU 2 867 T 6 gd Fa 9 n u oj joj 1 Figure 4 20 Servo Card No 1 73590 Disc Storage Unit Parts List for Servo Circuit Card No 2 figure 4 21 Reference Designator C1 C2 C4 C10 thru C16 CR1 thru CR6 Q1 thru Q12 Q19 Q20 Q21 Q13 Q15 Q14 Q16 Q17 Q18 R1 thru R16 R32 thru R36 R58 R59 R78 R79 R82 R83 R90 R17 R18 R19 R20 R21 R22 R26 R27 R23 R24 R25 R28 R29 R30 R31 R37 R38 R39 R50 R51 R52 R54 R81 R40 R64 R65 R85 thru R89 R41 R42 R43 R44 R45 R46 R47 R48 R49 R61 R53 R55 R62 R56 R57 R60 R63 R66 R67 thru R70 R71 thru R76 R77 R80 Part No 73480 73481 12812 12720 12501 12515 12801 12640 13005 12927 12909 12910 12921 12920 10125 11852 11247 11218 11185 11080 10975 11170 11065 11725 10995 11152 10874 10873 10056 10979 10049 10045 10055 10881 11164 10992 11068 10978 11166 10109 10041 16636 13209 10896 Servo No Part Name 2 assembly Servo circuit card No 2 Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor CER O 1uf 20 SOV 150D 6 8uf 20 30V 1
87. cs are stopped When it is in the CARTRIDGE LOCK position and both power switches are on the front door is locked and if a cartridge is in place ac is applied to the spin motor In the CARTRIDGE LOCK position ground from the POWER ON position of the front panel power switch is routed to the power supply as the motor switch on signal The motor switch on signal causes an amplifier to energize a relay which shunts the high ac line around the front panel power switch This arrangement keeps ac power to the drive until the heads are retracted from the discs when the front panel power switch is set to POWER OFF before the cartridge switch is set to the CARTRIDGE UNLOCK position This is to protect against head crashes caused by the heads being over the discs when the discs are moving too slowly to provide the air motion required to support the heads above below the disc surfaces 2 2 INDICATORS 2 2 1 POWER ON This indicator lights when 15V is available from the power supply This indicates that both the front panel and back panel power switches are on and that the line SM 2020 Disc Storage Unit fuses and F2 on the Power Supply are good The POWER ON indicator will stay on for approximately one second after the front panel power switch is set to POWER OFF when the cartridge switch is in the CARTRIDGE LOCK position 2 2 2 CARTRIDGE UNLOCK The CARTRIDGE UNLOCK indicator is on when the front door is unlocked so a cartridge may be removed or i
88. cylinders 000 and 200 3 28 It is possible to obtain a pattern which looks similar to the correct pattern but with incorrect amplitude Ignore these positions and continue to adjust the shutter position until the correct amplitude is obtained then continue adjusting until the correct pattern is obtained figure 3 13 If the pattern deviates from the CORRECT waveform while moving the carriage repeat steps 23 through 30 Tighten shutter mounting screws for the CORRECT pattern a Set channel 2 ground trace equal to that of ground trace of channel 1 b Set channel 2 vertical sensitivity to 0 5 V division c Input selector DC d Time base INT e Coupling DC f Slope g Mode AUTO GROUND 1 5 TO 2 0 VOLTS PEAK TO PEAK Figure 3 14 6 Waveform If waveform is less than 1 5 volts peak to peak recheck Lissajous pattern step 24 through 30 Disc Storage Unit SM 2020 Table 3 3 Optical Transducer Shutter Alignment continued Procedure Remarks c Verify that the TP7 figure 3 25 waveform has a peak to Sc GROUND peak amplitude of 1 5 volts to 2 0 volts as the carriage is 1 5 2 0 moved back and forth between VOLTS PEAK cylinders 000 and 200 TO PEAK Figure 3 15 TP7 Waveform If waveform is less than 1 5 volts peak to peak recheck Lissajous pattern steps 24 through 30 d Setting both TP6 and TP7 waveforms on scope figure GROUND 3 16 MODE CHOP verify ETT ape o
89. dy and access ready status signals are active low the controller can place a track number address on the address lines and issue a set cylinder signal The set cylinder signal causes a load cylinder register signal and resets the seek incomplete latch The load cylinder register signal triggers the 200 millisecond home position delay one shot which causes the access ready signal to become inactive When the heads are positioned over the commanded track the seek incomplete latch is kept in the reset state unless the 200 millisecond one shot has not timed out If the arrival flip flop is not set in less than 200 milliseconds the seek incomplete latch is set select seek 3 5 SM 2020 Disc Storage Unit incomplete and select access ready status signals are active to the controller The controller must now issue a new track command sequence track number then set cylinder Even if the heads are positioned to the correct track before a new track command is issued the seek incomplete status prohibits the CPU from using this address until a set cylinder signal causes the seek incomplete status to be reset During typical shut down the cartridge switch to set to CARTRIDGE UNLOCK which sets the motor switch on high causing the load heads signal to go low Drive ready becomes inactive and drive home op is set low The DRIVE READY indicator is dark and select drive ready and select access ready are inactive The initialize latch is set resetting th
90. e that the difference between the negative peak amplitudes does not exceed 200 mv m 200 MVOLTS Figure 3 16 Combined TP6 and TP7 Waveforms 33 Check Step a Set channel 1 scope probe Set oscilloscope to monitor channel 1 to pin S of A4 circuit card only b Verify that the voltage at Move carriage slowly back and forth A4 pin S swings to 2 0 volts through Cylinder 000 as the carriage is moved through Cylinder 000 34 Power down drive and reconnect a Position carriage at crash stop actuator leads to power supply b Set cartridge switch to CARTRIDGE card UNLOCK Set power switch to POWER OFF position d Set rear ac switch to OFF position e Connect red lead to E13 f Connect black lead to E14 3 29 SM 2020 I Disc Storage Unit Table 3 3 Optical Transducer Shutter Alignment continued Set front edge carriage indicator to scale indication 000 after heads load 35 Power up drive load heads and reposition the cylinder indicator on top of actuator if necessary 36 Verify proper head alignment by performing head alignment procedure 3 15 REMOVABLE DISC HEAD ASSEMBLY ALIGNMENT The removable disc head assembly should be aligned after the replacement of the optical transducer block the shutter assembly a removable disc head the disc spindle assembly or the acturator assembly NOTE It is not necessary to perform the steps to loosen the head arm clamping screws
91. e Disc Storage Unit by the Central Processing Unit CPU is effected through the DMA Disc Controller Part Number 900280 described in TM 2002 and LD 2002 Figure 1 1 shows the Disc Storage Unit before mounting in either a CPU cabinet or a Disc cabinet TO BE SUPPLIED Figure 1 1 Disc Storage Unit 1 1 SM 2020 Section 1 the general description includes both physical and functional Disc Storage Unit descriptions of the disc storage units as well as a brief description of disc organization as a memory device Section 2 contains descriptions of control functions and indicator significance Section 3 contains a detailed functional description of the disc drive units preventive maintenance cleaning removal replacement and alignment procedures followed by functional block and flow diagrams The functional block and flow diagrams are designed to provide all the information normally needed to isolate a malfunction to a replaceable assembly At the end of Section 3 is a troubleshooting flow diagram outlining logical steps a repairman may use to isolate the source of a trouble to a replaceable assembly Section 4 is an illustrated parts list 1 2 PURPOSE Each Disc Storage Unit also referred to as disc drive or drive is used to record write encoded serial data from the DMA Disc Controller controller within a discrete area on the disc specified by the controller Then on command by the controller ret
92. e cylinder and present cylinder address registers for track 0 Drive home op as bit 32 of the present cylinder address drives the actuator to home position When the discs slow to less than 2 of normal speed the 5V off signal disables the 5V regulator and the cartridge unlock solenoid and lamp are energized The front door may be opened and the cartridge removed The front panel power switch is then set to POWER OFF and the normal shut down sequence is complete If the power switch is set to POWER OFF first the ac power delay relay maintains ac to the drive for about two seconds so the same sequence has time to retract the heads so they won t crash but the front door will not be unlocked because the 15 volts used to energize the cartridge unlock solenoid will not be available when the spin stopped signal would have enabled the unlock circuits 3 6 HEAD POSITIONING FUNCTION The Head Positioning Function consists of the track number and head position comparison and the head position control circuits The head position control circuits are used for start up normal and shut down operations whereas the actual comparison of track number and head position occurs only during normal operation 3 6 1 TRACK NUMBER AND HEAD POSITION COMPARISON CIRCUITS figure 3 36 When the program requires that data be written on or read from a disc the controller puts the track number of the selected location on the address bus and issues a set cylinder command
93. e more frequent attention For example a drive being operated 350 400 hours per month should have six month checks performed at three month intervals Table 3 1 Six Month Preventive Maintenance Remove disc cartridge from drive and leave receiver door in opened position Remove drive power loosen two captive screws securing drive to cabinet and extend drive to obtain access to back and bottom of drive Remove nine screws securing bottom cover to drive chassis and remove cover Remove six screws securing component cover to drive chassis and remove cover 3 13 SM 2020 Disc Storage Unit Table 3 1 Six Month Preventive Maintenance continued 5 Remove two screws securing head cable bracket to drive chassis figure 3 1 HEAD CABLE CONNECTORS SCREWS SECURING SUPPORT BRACKET TIMING PULSE WIDTH ADJUSTING POT USED DURING SECTOR TRANSDUCER ALIGNMENT Figure 3 1 Drive Component Identifier 6 Remove all circuit cards from connectors Remove head connectors from Read Write circuit card 8 Remove four screws securing drive control logic card to mounting bracket 9 Position drive control logic card out of the way 10 While holding carriage assembly against rear crash stop insert head spacers between removable disc heads and the fixed disc heads figure 3 2 3 14 Disc Storage Unit 11 12 SM 2020 Table 3 1 Six Month Preventive Maintenance continued Step Procedure HEAD SPACERS
94. emovable disc sector transducer is moved or replaced The sector pulse 48 position should be checked after the delay alignment is completed Both alignments should be made whenever the interface circuit card is replaced Table 3 5 Removable Disc Transducer Alignments 1 Remove user cartridge remove a Set cartridge switch to the power and extend drive to access CARTRIDGE UNLOCK position back of drive b When CARTRIDGE UNLOCK lights remove the cartridge c Set power switch to POWER OFF position d Set ac switch on drive back panel to the OFF position 2 Remove drive component cover Set all test module switches to the OFF position 3 Install test module to the Jl connector 4 Power up drive install alignment a Set ac switch to ON position cartridge and load heads b Set power switch to POWER ON c Install alignment cartridge d Set cartridge switch to CARTRIDGE LOCK position e Set test module MAINT switch ON heads will load approximately 5 seconds after placing MAINT switch to the ON position 3 35 SM 2020 5 6 3 36 Disc Storage Unit Table 3 5 Removable Disc Transducer Alignments continued Procedure Remarks Set up oscilloscope to observe the read test points Position heads to Cylinder 100 200 Select head 0 Verify the time delay from the leading edge of the Index Pulse Sync Point to the synchroniz
95. ep 9 hold carriage assembly against rear crash stop while removing two screws securing the head adjusting bracket Remove two screws securing the head adjusting bracket and remove the bracket figure 3 23 Remove the appropriate head clamping screw hd 0 or hd 1 holding the head clamp Remove clamp from head arm assembly figure 3 23 Use extreme care while removing the head arm assembly to prevent damage to the head not being replaced Hold the carriage assembly against rear crash stop and slide the head arm assembly slightly forward toward disc spindle After the locating tab of the head arm stiffener clears the carriage slide head arm assembly out toward back of drive figure 3 24 3 19 REMOVABLE DISC HEAD ARM REPLACEMENT 1 5 3 40 Insert adjusting tab end of the head arm into the carriage slot figure 3 24 Position the slide spring of the head arm against the head load cam Applying a slight amount of pressure at the center of the head arm in direction perpendicular to head motion slide the head arm assembly towards back of drive Ensure that the head arm locating tab is within the carriage slot figure 3 24 Reassemble drive by performing in reverse order steps 4 through 10 of paragraph 3 18 NOTE a Position each adjusting screw in the center of the adjusting tab slot b Adjust the twist in the head cable springs such that the cables do not make contact with the A2 circuit card baseplate or the ca
96. esistor RN55D 3 57K 1 Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor 1 2w 1 8w 1 8w RCO7 4 7K 5 1 4w RCO7 7 5K RCO7 4 3K RCO7 6 2K RCO7 9 1K RNSSD 750 RN55D 200 RCO7 10 ohm RC32 160 RCO7 1 2K I ge of 1 4w 1 4w 1 4w 1 4w 41 1 8w 1 1 1 8w 1 4w ohm 5 1w 5 1 4w 1 I I SM 2020 Quantity Ref N Q Q ORAN NU gt PD NN n qr 187 SNP O n Be ACH 6 Rep Ts e T QQ N N N gt G 4 39 SM 2020 Disc Storage Unit Parts List for Read Write Circuit Card figure 4 23 continued Reference Designator R55 thru R58 R59 thru R62 R63 thru R66 R76 R67 R74 R75 R108 R109 R68 R69 R70 R71 R72 R73 R77 R78 R79 R80 R81 R96 R104 R105 R82 R83 R84 R85 R86 R87 R88 R89 R90 R91 R92 R95 R94 R95 R97 4 40 Part No 10061 10103 10056 10025 10412 11141 10858 10060 10046 11129 11059 10018 11058 10849 10949 11035 10954 10263 11034 10008 10058 10066 10417 10434 17012 2339 2338 17050 73332 74359 60748 18792 19110 18521 18930 Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resi
97. g data on one of the four disc surfaces and 4 retrieving data previously recorded on the disc reading Because the four functions can only be performed after the discs are rotating at a fixed velocity the drive sequences through a start up procedure each time a disc cartridge is inserted Then because the disc cartridge and read write heads would be damaged if the disc cartridge were removed while the drive was in operation the door permitting access to the disc cartridge is locked while the discs are rotating and there is a sequential stop procedure performed each time the motor switch is turned off A final constraint on effective drive operation is the quality and direction of motion of the air circulated within the drive enclosure During operation of the disc drive the read write heads fly over the recording surface of the disc supported only by a cushion of air 100 microns 0 0001 inch thick Therefore airborne contaminants might easily cause a head crash For this reason the drive has a special fan filter and ducting arrangement Figure 1 6 illustrates the relative sizes of some common hazards which may cause head crashes EDGE OF AVERAGE DIAMETER FLYING HEAD PAD OF HUMAN HAIR LINT AND DUST ABRASIVE FINGER PRINT SMUDGE AVERAGE HEAD SMOKE FLYING PARTICLE DISTANCE 250 MICRO IN APPROX 100 MICRO INCHES ALUMINUM SUBSTRATE 93 MPH SURFACE SPEED CYLINDER 0
98. gure 3 26 Actuator Mounting Screws TRANSDUCER BLOCK ALIGNMENT LIP Figure 3 27 Optical Positioning Transducer Removal and Replacement 3 46 Disc Storage Unit SM 2020 10 11 Remove transducer block by sliding it out towards front of drive figure 3 26 Place transducer block out of the way Temporarily remount actuator assembly to chassis by guiding the actuator forward along two guide pins and temporarily securing rear actuator frame mounting screw Loosen rear shutter adjusting bracket mounting screw two turns figure 3 28 Position carriage towards rear of drive While holding shutter assembly at back of drive loosen front shutter adjusting bracket mounting screw until shutter separates from carriage figure 3 28 Slide shutter assembly out from back of drive Remove two screws securing shutter to adjusting bracket and remove shutter SHUTTER ASSEMBLY REPLACEMENT NOTE Do not touch flat surfaces of the glass shutter Place shutter assembly on adjusting bracket such that the shutter is positioned away from the bracket and temporarily tighten the two screws Position carriage assembly toward back of drive Position the shutter assembly forward along the carriage assembly until the shutter adjusting bracket tab is positioned under the rear mounting screw Tighten rear shutter adjusting bracket mounting screw temporarily Tighten front shutter adjusting bracket mounting screw while holding adjusti
99. he two Screws CAUTION Ensure that clearance exists between the sector transducer and the sector pulley assembly 11 Install drive belt 12 Install component cover 13 Install drive into cabinet Disc Storage Unit SM 2020 14 15 Perform removable disc head arm alignment procedure in accordance with table 3 4 Install users cartridge and perform initialization of the fixed disc and the surface test diagnostic 3 32 DRIVE BELT REPLACEMENT 1 2 10 11 12 13 14 15 16 17 Remove disc cartridge Remove drive power and extend drive to obtain access to back and bottom of drive Remove nine screws securing bottom cover Remove cover Remove six screws securing component cover Remove cover Remove two screws securing switch fuse assembly to chassis figure 3 5 Position switch fuse assembly such that cables are not stretched and access can be made to the spin motor mounting bracket Loosen three screws securing the spin motor spring loaded mounting bracket to chassis figure 3 29 While pushing spin motor toward actuator remove drive belt from around pulley After marking remove four wires from capacitor assembly Remove one screw nearest disc spindle securing one leg of the blower assembly Loosen the other screws securing two legs of the blower assembly Replace new drive belt by performing in reverse order step 7 through 10 above Leaving the three screws that secure
100. here the carriage is positioned 32 tracks closer to the center of the disc than the commanded track address This causes the head positioning actuator to drive back to the home position and into the rear crash stop When the initialize latch was set it triggered the 200 millisecond home delay one shot After the one shot times out the drive home op signal is reset high removing the reverse drive signal to the head positioning actuator Under normal circumstances the spin motor reaches 70 of its normal speed within a few seconds after the motor starts so the 70 spin speed becomes active high When the 64 second delay times out the load heads signal becomes active high activating the drive forward to zero signal which is substituted for bit 16 of the cylinder register This becomes the shaped error signal which causes the head positioning actuator to drive the carriage forward This loads the heads and when they reach track 0 the track 0 signal clocks the initialize latch resetting it This makes the drive forward to zero signal inactive and the normal positioning signals control final positioning of the heads over track 0 The arrival flip flop is set and both R W safe 1 and R W safe 2 are active making the drive ready signal active Drive ready lights the DRIVE READY indicator and when this drive is selected by the controller the select drive ready and select access ready status signals to the controller are active Any time the drive rea
101. his relay delays removal of ac power to the primary 18970 Delay Relay of the power transformer to allow two seconds for the heads to unload before ac power is removed when the front panel power switch is set to POWER OFF position before the cartridge switch is set to CARTRIDGE UNLOCK 1 8 Disc Storage Unit 5 2020 Table 1 3 Component Description continued Description Blower The blower circulates cooling air from the prefilter Assembly through the absolute filter and provides continuous I air flow over the discs electronic cards and spin motor The blower is attached to the chassis and is belt driven by the spin motor 1 4 FUNCTIONAL DESCRIPTION The disc drive unit stores and retrieves data for use by the CPU The combination of a fixed disc and a removable disc permits the user to establish a limitless library of memory affords the user flexibility in applications and enables the user to protect files by duplication of data from disc to disc The functions of the disc drive unit are dictated by the physical characteristics of the disc as a memory device and the arbitrary system of organizing the storage surfaces of the discs so the user can recover specific segments at will Figure 1 4 illustrates the utilization of a disc surface and track spacing for 1 2 and 4 million data bytes per disc A bit cell is the area of the disc surface used to record one data bit Since there are the same number of bits per track
102. ilure can often be isolated to a specific assembly by means of deductive reasoning about the symptoms of a malfunction This kind of approach can be substituted successfully for extensive signal tracing of individual circuits at a considerable saving of time Therefore the flow chart figure 3 43 describing the sequential method of troubleshooting should be used to the maximum extent with only minimal reliance on specific procedures for checking individual circuits The basic approach to troubleshooting should be to first determine if the Disc Drive is malfunctioning Once the Disc Drive has been isolated as the cause of the malfunction further isolate the malfunction to one of the functions Refer to the appropriate repair procedure once the malfunctioning function is determined Troubleshooting may be continued by observing waveforms and voltages of a circuit and or circuit components to finally isolate the malfunction to a faulty integrated circuit package or discrete component if desired Before troubleshooting the drive perform the following checks to eliminate apparent malfunctions 1 Verify that the back panel power switch and the cabinet circuit breaker are both on and that the drive power cord is plugged into the receptacle in base of cabinet 2 Verify that the DMA Disc Controller is properly seated in its connector in the CPU that the rear edge connector connectors is securely attached to the controller and when applica
103. in order to check head alignment The head alignment tolerance is 455 Table 3 4 Removable Disc Head Alignment Procedure Remarks Remove user cartridge remove a Set cartridge switch to the power and extend drive to obtain CARTRIDGE UNLOCK access to back of drive b When CARTRIDGE UNLOCK lights remove the cartridge c Set power switch to the POWER OFF position d Set ac switch to drive rear panel to OFF position Remove drive component cover Set all test module switches to the OFF position CAUTION With power OFF the operator must ensure that the heads are not forced off the head load cam while loosening the head clamping screws 3 Insert test module interface cable into the J1 connector Disc Storage Unit SM 2020 Table 3 4 Removable Disc Head Alignment continued Procedure Remarks 4 Loosen both removable disc head Leave head clamping screws snug but clamping screws using had clamp not tight ing wrench figure 3 17 HEAD 0 CLAMPING SCREW HEAD 1 CLAMPING SCREW HD 0 ADJ SCREW HD 1 ADJ SCREW HD 2 ADJ SCREW HD 3 ADJ SCREW HEAD 3 CLAMPING SCREW HEAD 2 CLAMPING SCREW Figure 3 17 Head Adjusting Screw Location 5 Turn both head 0 and head 1 Insert screwdriver through cutout in adjusting screws counterclock the drive control logic circuit card wise until the screws just begin figure 3 17 to bind 6 Power up drive install alignment a Set ac power
104. ing timing pulse peaks The CORRECT timing pulse peaks The nominal correct time delay is 30 5 micro seconds from the start of sweep figure 3 21 however verify that time delay is within the range listed on the alignment cartridge being used NOTE If head 0 or head 1 time delays are incorrect perform adjust ment procedure of step 11 a Channel 1 Pin 10 of A2 circuit card LIM RD TP b Channel 2 Pin 11 of A2 circuit card LIM RD TP Sync TP1 of A5 circuit card INDEX REM Vertical 0 5 V division Time Base 5 uSec division Mode ADD Sync EXT Channel 2 INVERT Set test module SELECT CYLINDER switch ON Set CYLINDER ADDRESS switches 64 32 and 4 128 64 and 8 to ON c Press RESET then INITIATE push buttons a Set test module SELECT CYLINDER switch OFF b Set all CYLINDER ADDRESS switches OFF c Set SELECT HD SECT switch ON d Press RESET then INITIATE push buttons O Ignore polarity of the timing pulse REFERENCE PULSE TRIGGER POINT RECORDED BIT BURST USEC 25 uSEC 10 uSEC Figure 3 21 Timing Pulse Waveforms Disc Storage Unit SM 2020 Table 3 5 Removable Disc Transducer Alignment continued Procedure Remarks Select head 1 a Set test module HEAD 1 switch ON b Press RESET then INITIATE push buttons Verify head 1 time delay by This verifies that head 1 timing pulse observing waveform of figure 3 21 occurs
105. ing the head clamp Remove clamp from head arm assembly figure 3 23 Use extreme care while removing the head arm assembly to prevent damage to the head not being replaced 11 Hold the carriage assembly against rear crash stop and slide the head arm assembly slightly forward toward disc spindle After the locating tab of the head arm stiffener clears the carriage slide head arm assembly out toward back of drive figure 3 24 3 21 FIXED DISC HEAD ARM ASSEMBLY REPLACEMENT 1 Insert adjusting tab end of the head arm into the carriage slot figure 3 24 2 Position the slide spring of the head arm on top of the head load cam figure 3 24 3 Applying a slight amount of pressure at the center of the head arm in the direction perpendicular to head motion slide the head arm assembly towards back of drive Ensure that the head arm locating tab is within the carriage slot figure 3 24 3 42 Disc Storage Unit SM 2020 10 Replace head adjusting mounting bracket Position each adjusting screw in the center of the adjusting tab slot Replace head clamp and tighten head clamping screw snug but not tight Turn the head adjusting screw of the head replaced counterclockwise until screw just begins to bind Turn head adjusting screw clockwise four complete revolutions this will set the adjusting tab in the center of the carriage bar Reassemble drive by performing in reverse order steps 1 through 8 of paragraph 3
106. is circuit card contains the circuits that monitor 73720 drive status compare carriage position to the controller commanded track number decode head selection signals from the controller and control read write operations according to controller commands and drive status It is mounted at the rear of the drive chassis and contains the interface connectors for the controller and other drive units the mounting connectors for five other printed circuit cards and connectors for chassis mounted assemblies This circuit card interfaces the controller to the 73540 drive It contains the logic to generate the sector and index pulses for both the removable disc and the fixed disc and the logic to determine if the disc rotation has stopped or if the disc is rotating at greater than 70 rated speed This circuit card contains the analog circuits that 73590 processes the optic transducer outputs to determine carriage position motion and direction track 0 and home position detection and a linear tachometer signal It also contains the mixer amplifier for the primary positioning signal 1 7 SM 2020 Disc Storage Unit Table 1 3 Component Description continued Part Name Description Number Servo This circuit card contains circuits which convert 73480 No 2 digital positioning data into an analog voltage A3 an electronic tachometer mixing circuits for the final positioning signal and the preamp drivers that control both forward
107. it SM 2020 Quantity Ref REN ODF A HED FREON 4 32 SM 2020 ADDR 1 5 ADDR ADDR 3 ADDR 2 us SCIR 24 SCTR 18 SCTR TPI s Cs iO Figure 4 19 Interface 73540 LLL i U7 ull ns Disc Storage Unit Disc Storage Unit Parts List for Servo Circuit Card No 1 figure 4 20 Reference Designator C1 C2 C6 C7 C9 C10 thru C13 CR1 thru CR7 CR9 thru CR18 CR8 01 02 08 09 03 04 05 06 07 R1 R2 R3 R7 R12 R16 R17 R29 R31 R32 R36 R37 RA5 RA9 R57 R69 R71 R76 R79 R80 R4 R10 R19 R51 R52 R67 R68 R88 R5 R11 R24 R65 R66 R6 R8 R60 R61 R64 R9 R13 R14 R38 R42 R55 R56 R15 R18 R20 R21 R22 R23 R25 R27 R35 R41 R28 R70 R74 R30 R33 R81 R39 R43 R48 R44 R47 R46 R50 R53 R54 R58 R59 R72 R62 R63 R73 R75 R77 R78 R82 Part No 73591 12623 12812 12818 12513 12505 12720 12510 13005 13009 12909 12910 12920 12927 10873 10056 10029 11066 10995 11185 11230 10988 11230 11052 11162 10149 16729 10142 10978 11156 11068 10969 11071 11201 10970 11079 10849 10971 11193 11044 11169 11064 11083 Part Name Servo circuit card No 1 Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor DM15 100pf 5 500V CER 0 1uf 20 50V CER luf 520 50V 192P 0 022uf 10 80V 1
108. ite current so the low numbered tracks the tracks farthest from the center of the disc are recorded with more write current than the high numbered tracks 6 The Read Function figure 3 40 decodes the select fixed disc and select lower head signals from the controller to select one of the four read write heads this is done by the same circuits in both the Read Function and the Write Function When the read gate signal from the controller is active the signals from the selected head are amplified and converted to a logic signal called raw data Raw data is used by the variable frequency oscillator VFO to synthesize a read clock and reformat the raw data to a read data signal synchronized to the read clock These signals are used by the controller to reconstruct the data initially recorded on the disc The six functional groups are described in detail in the following paragraphs The functional block diagrams timing diagrams and flow charts provide all the information normally needed to isolate troubles to a replaceable card or mechanical assembly 3 4 POWER FUNCTION figure 3 34 The power cord for the disc drive unit is plugged into the ac receptable at the bottom of the CPU or Disc Cabinet During normal day to day operation the back panel power switch is left set to ON so power to the drive is controlled by the front panel power switch When the front panel power switch is set to the POWER ON position ac is applied to the power tran
109. m the present cylinder address counter A carry is generated by the adders each time the new address from the cylinder register is for a track number higher than the present address The outputs from the exclusive or function is the binary difference between the cylinder register contents and the present cylinder address counter contents when the new address is for a lower numbered track than the present head location The output of the exclusive or function is the complement of the difference when the new address is for a higher numbered track 3 6 2 HEAD POSITION CONTROL CIRCUITS figure 3 37 The head position control circuits form a closed servo loop When a new track number is entered from the controller the difference 0 signal becomes inactive high and the forward switch is energized if drive forward is high or the reverse switch is energized if drive forward is low The shaped error signal is passed by the forward switch or the inverted shaped error signal is passed by the reverse switch to become the positioner drive signal The positioner drive signal is combined in a summing amplifier with feedback and tachometer signals to become the forward preamp drive or reverse preamp drive signal Whichever of these signals exist cause their drive amplifier to provide current to move the head positioning actuator The forward drive amplifier passes current from the 15V supply through the actuator to ground The reverse drive amplifier passe
110. move drive component cover Insert test module interface cable into J1 connector Connect one scope probe between TP4 POS DR of A4 circuit card and channel 1 of oscilloscope Connect second scope probe between pin E ACCESS READY of AS circuit card and channel 2 of oscilloscope Connect third scope probe between pin P SET CYLINDER of 5 circuit card and EXT SYNC on oscilloscope Set oscilloscope controls to the following Power up drive Set test module switch to perform an automatic seek operation from track O to track 67 154 to verify Set OFF o an p a Set cartridge switch to the CARTRIDGE UNLOCK When CARTRIDGE UNLOCK lights remove the disc cartridge Set power switch to the POWER OFF position Set ac switch on drive rear panel to OFF position all test module switches to the position Channel 1 Vertical Sensitivity to 2 V division Channel 2 Vertical Sensitivity to 2 V division Time base to 10 mS division Sync EXT Mode Chop Set power switch on rear panel of drive to ON position Set switch to POWER ON position Set switch to CARTRIDGE LOCK position Set test module MAINT switch to ON Heads will load approximately 5 seconds after placing MAINT switch to the ON position Set test module CYLINDER ADDRESS switches 64 2 and 1 128 4 and 2 to ON Set test module SELECT CYLINDER switch ON Disc Storage Unit SM 2020 Table 3 6 Access Time Alignment co
111. ng bracket against the carriage NOTE Do Not Touch Glass Shutter Tighten rear shutter adjusting bracket mounting screw Replace optical positioning transducer block assembly by performing in reverse orders steps 4 and 5 of paragraph 3 26 Reassemble remaining drive components by performing in reverse order steps 6 through 12 of paragraph 3 22 Verify correct alignment of the optical positioning transducer assembly Shutter assembly and removable disc heads by performing alignments of tables 3 3 and 3 4 3 47 SM 2020 Disc Storage Unit CRASH STOP SCREW SHUTTER BRACKET SCREWS Figure 3 28 Shutter Removal Crash Stop and Shutter Adjusting Bracket Mounting Screws Disc Storage Unit SM 2020 3 28 SPIN MOTOR REMOVAL 10 Remove disc cartridge from drive Remove power and extend drive to obtain access to back and bottom of drive Remove nine screws securing bottom cover to drive chassis and remove bottom cover Remove six screws securing component cover to chassis Remove cover Remove two screws securing switch fuse assembly to chassis figure 3 5 Position switch fuse assembly such that access can be made to the motion plate mounting screws Loosen three screws securing the spin motor spring loaded mounting bracket to chassis figure 3 6 While pushing spin motor toward actuator remove drive belt from around pulley Remove four screws securing the spin motor to the mounting bracket figure 3 29 Remove
112. ng steps are to obtain the correct shutter to mask clearance CAUTION With the actuator disconnected the operator must insure that the carriage is positioned against the rear crash stop before loading and unloading the disc cartridge and start ing the spin motor 16 Insert an operational disc cart ridge 17 Set cartridge switch to CARTRIDGE Verify that the discs are spinning at LOCK position rated speed 18 Set maximum clearance between the a Position carriage assembly to rear shutter and the mask figure 3 9 crash stop and loosen forward mounting screw figure 3 11 Position the front of the shutter assembly toward the actuator FRONT SCREW REAR SCREW Figure 3 11 Shutter Mounting Screws 3 25 SM 2020 19 20 21 22 23 3 26 Disc Storage Unit Table 3 3 Optical Transducer Shutter Alignment continued Procedure Remarks Connect one scope probe between channel 1 on the oscilloscope and TP6 on A4 circuit card Connect another scope probe between HORZ INPUT EXT INPUT on oscilloscope and TP7 on A4 circuit card Loosen the forward shutter mount ing screw and position shutter slightly away from the actuator motor Verify that clearance between the shutter and mask still exists While monitoring the oscilloscope display move the carriage back and forth between the rear crash stop and just prior to the head load position heads fly over disc b Manually move
113. nserted It indicates that power is applied to the drive circuits and the discs are stopped 2 2 5 READY The READY indicator is on when the drive is operating the initial time delays have expired and the heads are loaded READY will be extinguished anytime an unsafe condition is detected by the status circuits Disc Storage Unit 5 2020 Section 3 MAINTENANCE 3 1 SCOPE Section 3 contains information and instructions for procedures required to keep the drive in proper operating condition Maintenance information includes a detailed functional description and preventive corrective maintenance procedures The detailed functional description and its supporting illustrations figures 3 34 through 3 40 near the end of this Section provide the information usually needed to determine appropriate corrective action Preventive maintenance is defined as the systematic care inspection and tests of the drive to keep it in operating condition and to correct minor failures before they develop into major failures General preventive maintenance categories are adjust align check clean inspect lubricate replace and test for operational readiness Corrective maintenance is defined as the systematic isolation of a fault in failed drive This includes tests necessary to isolate the faulty component the procedures necessary to remove and replace it and the tests necessary to ensure the drive is operating properly 3 2 S
114. nt of the spin motor until its armature is rotating at a safe speed The ground connection from the Drive Control Logic card is routed through the front panel power switch in the POWER ON position and the cartridge switch in the CARTRIDGE LOCK position and back to the Drive Control Logic card to become the motor switch on signal The motor switch on signal and the read write safe 2 signal are combined to disable the 5 volt regulator when the drive is in normal operation and the cartridge switch is set to the CARTRIDGE UNLOCK position When the motor switch on signal is low POWER ON and CARTRIDGE LOCK it enables the 5 volt regulator and discharges the input capacitor on the delay relay driver which energizes the ac power delay relay If the front panel power switch is set to POWER OFF before the cartridge switch is set to CARTRIDGE UNLOCK the delay relay driver keeps the ac power delay relay energized for about two seconds until the input capacitor charges enough to turn off the delay relay driver This allows the dc voltages to remain long enough to retract the read write heads from the discs before power is removed from the spin motor After all the dc voltages are in the safe operating range the power safe signal is made active low The power safe signal is routed to the Drive Control Logic where it is used by the Start Stop and Status Function 3 5 START STOP AND STATUS FUNCTION figure 3 35 With the front panel power switch in the PO
115. ntinued Procedure Remarks Press test module RESET pushbutton Press test module INITIATE push button The servo drives the heads between tracks O and 67 for 100 Models or tracks 0 and 134 for 200 Models Verify that average access time without overshoot is less than 35 mSec maximum If overshoot or access time is Sync on pin 4 LINEAR ZONE ENABLE greater than allowable adjust of A3 circuit card potentiometer R77 on A3 circuit Set Time Base to 5 mSec division card to obtain a waveform similar to the one shown in figure 3 22 LINEAR ZONE lt 1 TRACK ALLOWED ALLOWED NOT ALLOWED Figure 3 22 Access Time Waveforms 3 18 REMOVABLE DISC HEAD ARM ASSEMBLY REMOVAL 1 Remove disc cartridge from drive 2 Remove drive power and extend drive to obtain access to back of drive 3 Remove six screws securing component cover to drive chassis Remove component cover 4 Remove two screws securing head lead support bracket figure 3 1 Remove four screws securing drive control logic circuit card to mounting bracket and slide all PC Cards toward rear of drive Remove the Al and A2 circuit cards from connectors Disconnect JO through J3 head cable connectors from the A2 circuit card figure 3 1 SM 2020 10 11 Disc Storage Unit Loosen two screws securing the head adjusting bracket and remove the bracket out the appropriate head cable hd 0 or hd 1 CAUTION When performing st
116. ock firmly block figure 3 10 and position against actuator assembly frame block towards back of drive b Keep carriage against crash stop MOUNTING SCREW Figure 3 10 Block Screw 12 Keeping transducer block firmly When HOME POSITION line goes low downward against the actuator logical 0 the home position for the frame slowly move the block carriage has been detected towards the disc spindle until the HOME POSITION line goes low 13 Continue moving the block toward Each division of the scale indicator the disc spindle approximately is 0 025 inch 0 020 to 0 040 inch further from the position observed in Step 12 14 Being careful not to shift the This alignment insures that the home transducer block position torque position is detected before the the screw mounting the block to carriage assembly contacts the crash the actuator frame to 8 inch stop pounds 15 Verify that the transducer block a Move the carriage assembly approx has been positioned to detect imately 1 2 inch from the rear home position crash stop b Slowly move the carriage assembly toward the rear crash stop 3 24 Disc Storage Unit SM 2020 Table 3 3 Optical Transducer Shutter Alignment continued Procedure Remarks c Observing the scope display verify that the HOME POSITION signal goes low when the carriage is 0 020 to 0 040 inches from the crash stop and remains low when the carriage is against the crash stop The followi
117. oes not effect head posi while observing the oscilloscope tioning indicated by a change in waveform the waveform shown in figure 3 20 b Ensure that a space exists between adjacent head clamps figure 3 17 c If the waveform changes while tightening the clamping screw 1 loosen clamping screw 2 turn adjusting screw to obtain correct waveform 3 repeat steps 14 and 15 16 Select Head 1 Head 1 is aligned a Set test module switch Head 1 ON in the following steps b Press RESET c Press INITIATE d The bottom head of the removable disc is now selected to read 17 Using the head 1 adjusting screw Head 1 is the head facing the bottom align head 1 using the procedures surface of the removable disc outlined in steps 11 through 15 18 To ensure correct alignment set This will ensure that the carriage was the carriage to Cylinder 000 not moved off track 105 210 during and then return the carriage to the head adjustment Cylinder 105 210 3 34 Disc Storage Unit SM 2020 Table 3 4 Removable Disc Head Adjustment continued Procedure Remarks 19 Verify that the CORRECT waveform is observed for both head 0 and head 1 20 After successful head alignment perform removable disc sector transducer alignment 3 16 REMOVABLE DISC SECTOR TRANSDUCER DELAY AND SECTOR PULSE 48 ALIGNMENT EE ES 5 a The removable disc sector transducer delay alignment should be made whenever the r
118. omes active high The removable disc notch detected signal triggers a removable disc transducer delay one shot The delay caused by this one shot is adjustable from 18 to 180 micro seconds in order to account for differences in transducer alignment in different drives This makes it possible to use removable discs in all drives of the same model At the end of the variable delay a 730 microsecond delay one shot is triggered The index notch will be detected before the 730 microsecond one shot times out and will trigger the 5 microsecond index one shot which generates the removable disc index pulse The 47 sector notches will all be detected after the 730 microsecond delay so a removable disc sector pulse is generated each time the 730 microsecond delay one shot is triggered The forty eighth sector pulse is generated by a 210 microsecond delay one shot that is triggered by the removable disc index pulse The removable disc index pulse triggers a retriggerable 57 millisecond one shot When removable disc index pulses occur oftener than 3 9 SM 2020 Disc Storage Unit 57 milliseconds the one shot remains set and the 70 spin speed signal is always high The sector and index pulses are gated to the controller when the drive is selected 3 8 WRITE FUNCTION After the controller has caused the heads to be positioned over a specific track the index and sector pulses provide the information necessary for the controller to indentify a specific sec
119. orm steps 5 through 14 of the actuator assembly removal and replacement procedure paragraph 3 22 4 Remove screw securing optical positioning transducer block to actuator frame figure 3 10 Slide transducer block out towards front of drive figure 3 27 6 Temporarily remount actuator assembly to drive chassis by guiding the actuator forward along two guide pins and temporarily securing rear actuator frame mounting screw 7 Loosen two screws securing shutter assembly to shutter adjusting bracket figure 3 11 8 Position shutter assembly towards the actuator and temporarily tighten the two mounting screws 3 25 OPTICAL POSITIONING TRANSDUCER REPLACEMENT 1 Remount optical positioning transducer assembly by performing in reverse order steps 4 5 and 6 of paragraph 3 24 2 Reassemble remaining drive components by performing in reverse order steps 6 through 14 of paragraph 3 22 3 Verify correct alignment of optical positioning transducer assembly shutter assembly and removable disc heads by performing alignments of tables 3 3 and 3 4 3 26 SHUTTER ASSEMBLY REMOVAL 1 Remove disc cartridge Remove power and extend drive to obtain access to back of drive 3 Perform steps 5 through 13 of the actuator assembly removal and replacement procedure paragraph 3 22 4 Remove screw securing optical positioning transducer block to actuator frame figure 3 10 3 45 SM 2020 Disc Storage Unit FRONT SCREW REAR SCREW Fi
120. rieve that stored data read and send it to the controller Each disc drive contains a permanently mounted fixed disc and when operating a removable disc cartridge removable disc shaft at 1500 rpm during operation initialized for use before data is recorded stored on it Each removable disc cartridge must be may be retrieved by any other disc drive with the same model number Both discs are rotated on the same Thereafter the data The Disc Storage Unit model number indicates the density of storage available on a disc Table 1 1 lists the different model numbers and contrasts their storage capacity It is possible to have up to four disc drives in a Data Processing System Data bytes are transferred directly between the CPU core memory and either disc in any drive within a system through the controller so it is possible that a Data Processing System may have nearly 34 million bytes of available memory Table 1 1 Series Per Per Per Per Per Number Number of Sector Track Cylinder Disc Drive Data Bytes Total Bytes Data Bytes Total Bytes Data Bytes Total Bytes 1 2 1 056 000 1 440 000 2 112 000 2 880 000 4 224 000 5 760 000 Storage Capacity of Disc Storage Units 2 112 000 2 880 000 4 224 000 5 760 000 8 448 000 11 520 000 Maximum System 8 448 000 11 520 000 16 896 000 23 040 000 53 792 000 46 080 000 Disc Storage Unit SM 2020 1 3 PHYSICAL DESCRIPTION The dimension
121. rriage when the carriage is in motion Perform removable disc head arm alignment Disc Storage Unit SM 2020 HEAD 0 CLAMP SCREW HEAD 1 CLAMP SCREW HEAD 2 CLAMP SCREW HEAD 3 CLAMP SCREW ADJUST BRACKET MOUNTING SCREWS Figure 3 23 Mounting Screws for Head Clamps and Adjusting Bracket LOCATING TAB ADJUSTING TAB Figure 3 24 Head Removal and Replacement 3 41 SM 2020 Disc Storage Unit 3 20 FIXED DISC HEAD ARM ASSEMBLY REMOVABLE 1 Remove disc cartridge from drive 2 Remove drive power and extend drive to obtain access to back of drive 3 Remove six screws securing component cover to drive chassis Remove component cover 4 Remove two screws securing head lead support bracket to drive chassis figure 3 1 5 Remove four screws securing drive control logic circuit card to mounting bracket and slide all PC cards toward rear of drive 6 Remove the Al and A2 circuit cards from connectors 7 Disconnect JO and J3 head cable connectors from the A2 circuit card figure 3 1 8 Loosen two screws mounting head wire cable to the support bracket and slide out the appropriate head cable hd 2 or hd 3 CAUTION When performing step 9 hold carriage assembly against rear crash stop while removing two screws securing the head adjusting bracket 9 Remove two screws securing the head adjusting bracket and remove the bracket figure 3 23 10 Remove the appropriate head clamping screw hd 2 of hd 3 hold
122. rvo circuit card No 1 Servo circuit card No 2 Read write circuit card VFO circuit card Drive control logic circuit card Spin motor assembly Flange bearing Standoff Tape Door assembly Bracket Screw Disc Storage Unit Quantity TON ft OP ft ft ft dH IR E ER ep N Disc Storage Unit SM 2020 HEAD CABLE CONNECTIONS TO READ WRITE CARD L LATCH LINK FROM FIXED D DISC COVER ASSEMBLY Figure 4 1 Disc Drive Assembly SM 2020 Parts List for Receiver Assembly figure 4 2 Reference No WANA 4 4 Part Number 74408 73267 73271 73271 13330 14024 14003 73265 13429 73276 73275 73372 73278 73347 73299 73298 74407 13346 13358 13349 14004 73375 14025 Part Name Guide strip assembly Strap Guide right side Guide left side Screw Washer lock Washer plain Receiver Screw Extension right side Extension left side Ramp right side Ramp left side Tape Stop Spring Tubing heat shrink Screw Screw Screw Washer plain Shield Washer lock Disc Storage Unit Quantity gt KSS NN PR PSR RS ae Disc Storage Unit SM 2020 Figure 4 2 Receiver Assembly 73170 SM 2020 Parts List for Fixed Disc Cover Assembly Right Side figure 4 3 Reference No OANA U1 Q 4 6 Part Number 73255 13364 14026 73296 18660 13318 73282 13313 73270 74390 B74373 13334 24680 19120 73190 73606 19280 732
123. s current from ground through the actuator to the 15V supply This current causes a feedback signal to the summing amplifier that is proportional to the amount of 3 7 SM 2020 Disc Storage Unit current flowing through the actuator and opposite to the polarity of the positioner drive signal negative feedback When the carriage is out of the linear zone only about one eighth of the feedback is input to the summing amplifier As the head positioning actuator rotates the carriage is moved The read write heads are mounted on the carriage and so is the mask for the shutter assembly The mask consists of a sheet of optical glass which is overlaid with several slot patterns One of the slot patterns resembles a picket fence in that there are alternate transparent and opaque slots spaced at track intervals Behind this group of slots are two photodiodes which receive varying amounts of infrared radiation from a light emitting diode LED radiation source as the mask moves The outputs of the photodiodes are the and B signals The physical spacing of the photodiodes is such that when considered ac signals there is approximately a 90 phase shift lead or lag between A and B A and B signals are combined in amplifier to become A B algebraic sum not logical and A B The output of one dA amplifier is rectified filtered and compared to a reference voltage The difference between the reference volt
124. s of the drive are listed in table 1 2 The front door of the drive is pulled forward and down to permit insertion and removal of disc pack cartridges Disc storage Unit 0 is mounted in the CPU cabinet When a system includes two three or four drives the additional drives are mounted in a Disc Cabinet and designated as Disc Storage Units 1 2 and 3 Two cables between the CPU Cabinet and the Disc Cabinet connect the drives in a daisy chain fashion The disc drive components are mounted on a preformed aluminum chassis Mounted lengthwise in the center of the chassis is a solid anodized aluminum base bar which reinforces the chassis Mounted on the solid base bar are the disc spindle rotary actuator motor and optical transducer The power supply card and components of the air filtration system are mounted on the bottom of the chassis 11 of the drive control and servo electronics are mounted at the top rear of the chassis Covers completely enclose all of the drive components to protect them against contamination and physical damage The drive consists of an optically controlled closed loop servo mechanism carrying four read write heads one per disc surface a spin motor which rotates both discs at 1500 RPM and the read write electronics Both discs are serviced by the same moving servo mechanism When commanded by the controller the servo mechanism moves the four read write heads over the same area cylinder of both rotating discs The
125. servo mechanism consists of a head carriage whose linear motion is provided by a rotary actuator and controlled by closed loop servo system with an optical position sensing device in the feedback loop During a write operation the heads are positioned over the desired track the write electronics receive serial data from the controller and generate write current transitions in the read write head using the double frequency recording method Later during a read operation after the heads are positioned over the desired track the read electronics amplify detect and filter the flux transitions from the disc and generate serial read data and read data clocks which are sent back to the controller for processing 1 3 SM 2020 Disc Storage Unit Figure 1 2 shows the locations of drive subassemblies on top of the chassis Figure 1 3 shows the drive components mounted on the bottom of the chassis Table 1 3 lists and describes components of all three Models of the disc drive Table 1 2 provides a source of quick reference data for the drive DISC SPINDLE ASSEMBLY RECEIVER ASSEMBLY HEAD ARM ASSEMBLY ACTUATOR ASSEMBLY VFO PCB A1 DRIVE CONTROL 0 SERVO NO 2 PCB A3 SPIN MOTOR ASSEMBLY READ WRITE PCB A2 INTERFACE PCB A5 SERVO NO 1 PCB A4 Figure 1 2 Cartridge Receiver Area with Component Cover Removed 1 4 Disc Storage Unit AIR FILTER CAPACITOR ASSEMBLY POWER TRANSFORMER POWER OFF DELAY RELAY SWITCH FUSE
126. sformer and the cartridge motor switch The power transformer provides the return line for the spin motor and stepped down ac voltages to the 15 volt bridge rectifier and the 5 volt bridge rectifier When the ac line is 115 volts the spin motor return tap on the power transformer and the high side of the ac line are 115 volts When the ac line is 220 volts the voltage supplied to the spin motor is from the power transformer primary and is 115 volts so long as the line connections to the power transformer are correct for the line voltage The 15 unregulated voltage is applied to the drive home amplifier on the power supply through F4 to the reverse amplifier on the power supply and to the Drive Control Logic mother board as 15V raw and through F2 to the 15 volt regulator The 15V raw is applied to the cartridge unlock solenoid The 15 volts regulated is supplied through the Drive Control Logic to the front panel lamps so the POWER lamp is on whenever there is 15 volts available in the drive The 15 volts unregulated is routed through F5 to the forward amplifier on the power supply and through F3 to the 15 volt regulator SM 2020 Disc Storage Unit After power has been switched on to the drive and the cartridge switch set to CARTRIDGE LOCK the high side of the ac line is connected through the receiver interlock switch to the motor start relay if there is a cartridge in the receiver The motor start relay limits the starting curre
127. ssembly be replaced as a unit Removing the disc spindle assembly involves removing several assemblies therefore this procedure provides the removal procedure for those assemblies 1 Remove disc cartridge 2 Remove power extend drive and disconnect power cable If rack mounted remove drive and place on work bench 3 Using 1 8 inch allen wrench remove six screws securing component cover to drive chassis and remove cover 4 Remove nine screws securing bottom cover to drive chassis Turn drive on its side and remove bottom cover 5 Remove fixed disc sector pulley assembly figure 3 30 a Remove drive belt from around fixed disc sector pulley assembly b Loosen two set screws securing fixed disc sector transducer and slide sector transducer out of the way c Using 1 16 inch allen wrench loosen two set screws located in sector pulley d Using 5 32 inch allen wrench remove allen head screw securing fixed disc sector pulley assembly to the disc spindle assembly Pull off the fixed disc sector pulley 6 Place drive in upright position to remove fixed disc cover assembly and proceed as follows CAUTION Ensure that the carriage assembly is against the rear crash stop 3 50 Disc Storage Unit SM 2020 FIXED DISC SECTOR PULLEY SECTOR TRANSDUCER SCREWS ALLEN HEAD SCREW SET SCREW 1 OF 2 Figure 3 30 Fixed Disc Removal Fixed Disc Sector Transducer and Sector Pulley 3 51 SM 2020 Disc Storage Unit
128. stor Resistor Resistor Resistor Resistor Resistor Resistor Part Name RCO7 3 3K 5 1 4w RCO7 12K 5 1 4w RCO7 2K 5 1 4w RCO7 100 ohm 5 1 4w RC32 30 ohm 5 RNSSD 825 ohm 1 1 8w RNSSD 1 24K 1 1 8w RCO7 3K 5 1 4w RCO7 750 ohm 5 1 4w RNSSD 619 ohm 1 1 8w RN55D 4 02K 1 1 8w RCO7 51 ohm 5 1 4w RN55D 3 92K 1 1 8w RN55D 1K 1 1 8w RN55D 1 78K 1 1 8w RN55D 402 ohm 1 1 8w RN55D 2 02K 1 1 8w RC20 3 9K 5 1 2w RN55D 392 ohm 1 1 8w RCO7 20 ohm 5 1 4w RCO7 2 4K 5 1 4w RCO7 5 1K 5 1 4w RC32 47 ohm 5 1w RC32 240 ohm 5 lw 99 o Integrated Circuit SN74107 Integrated Circuit Integrated Circuit Integrated Circuit Shield lower Shield upper Screw 4 40 X 0 38 Nut 4 40 nylon Spacer 4 nylon Connector pins Test points 753 UA711 9601 nylon Quantity PRED FA BO B in n 4 Disc Storage Unit SM 2020 Figure 4 23 Read Write 73460 4 41 SM 2020 Disc Storage Unit Parts List for Power Supply Circuit Board figure 4 24 Reference Designator C1 C5 C6 C7 C15 thru C18 C2 C3 C8 C10 C12 C21 C22 CR1 CR2 CR3 CR10 CR15 CR4 thru CR7 CR13 CR16 CR21 CR22 CR8 CR9 CR12 CR17 thru CR20 CR11 CR14 F1 F2 F3 F4 F5 Kl 01 02 05 06 012 020 Q4 Q8 Q11 Q19 5 Q Q7 Q9 Q10 Q17 Q18
129. switch to ON position cartridge and load heads b Set power switch to the POWER ON position c Install alignment cartridge d Set cartridge switch to LOCK position e Set test module MAINT switch ON Heads will load approximately 5 seconds after placing MAINT switch to the ON position 3 31 SM 2020 Table 3 4 Disc Storage Unit Removable Disc Head Adjustment continued 10 3 32 NOTE 1 Do not perform step 7 through step 18 of this alignment procedure until the disc has been spinning for at least one hour NOTE 2 It is possible to enter state ments at the VDT instead of using the test module Set up oscilloscope to observe the read test points When aligning a Model 2X15 100 Disc Drive Unit position heads to cylinder 105 When aligning a Model 2X15 200 Disc Drive Unit position heads to Cylinder 210 After positioning the heads at Cylinder 105 disable the cylinder accessing function Select head 0 This time allows for thermal expansion of the alignment cartridge When the VDT is used instead of the test module the Disc Drive Unit being aligned must be selected before step 7 a b mo ho a Channel 1 TP18 on Control Logic circuit card Channel 2 TP19 on Control Logic circuit card Sync 1 of AS circuit card INDEX REM Vertical 0 2 V division Time Base 5 mSec division Sync EXT Mode ADD Channel 2 INVERT Set test module CYLINDER ADDRESS
130. t 5 21 5 15 Removable Disc Head Assembly Alignment EE 3 30 3 16 Removable Disc Sector Transducer Delay and Sector Pulse 48 Alignment ie tie wh EM GE wan es ee a Wie PG 3 35 3 17 Access Time Alignment Aya NE EE 3 18 Removable Disc Head Arm Assembly Removal EX Galea 20 fer 3 39 3 19 Removable Disc Head Arm Replacement 3 40 111 SM 2020 SECTION 3 Q Q Q RA RA EA N SECTION 4 4 1 4 Disc Storage Unit MAINTENANCE continued Page Fixed Disc Head Arm Assembly Removable 3 42 Fixed Disc Head Arm Assembly Replacement 3 42 Actuator Assembly Removable s az k eae 3 43 Actuator Assembly Replacement PUR a a 3 45 Optical Positioning Transducer Removal PO Aa se v 13 45 Optical Positioning Transducer Replacement 3 45 Shutter Assembly Removal 2 2 2 2 2 2 3 45 Shutter Assembly Replacement 2 2 3 47 Spin Motor Removal s k S Su 3 49 Spin Motor Replacement k k Ga og 3 50 Fixed Disc Removal SU GND ide ae 3 50 Fixed Disc Assembly Replacement ao eat Ga W sS 3 54 Drive Belt Replacement 3 55 PARTS LISTS Scope
131. t 2 3 65 WRITE FLOW DIAGRAM CONTROLLER SELECTS DRIVE WAIT READ 55 Y REPEAT YES CONTROLLER COMMANDS NEW TRACK NUMBER CONTROLLER INACTIVATES a WRITE GATE ACCESS TRIGGER 25 uSEC READY ERASE GATE DELAY ONE SHOT YES WAIT Ne READY NO SELECTS RE CONTROLLER SENDS SELECTS READ WRITE HEAD WRITE GATE AND CRC BYTES CONTROLLER SENDS READ CONTROLLER GATE INACTIVATES WRITE GATE CONTINUE TRIGGER 25 uSEC ERASE GATE DELAY ONE SHOT NEXT SECTOR REQUIRED NEXT SECTOR REQUIRED YES YES CONTROLLER SENDS WRITE GATE TE DRIVE READY COMMAND FROM CONTROLLER MORE YES THAN ONE HEAD SELECTED CONTROLLER SENDS READY AND DOUBLE FREQUENCY ACCESS READY WRITE DATA INACTIVE CONTINUE ALL DATA WRITTEN MANUAL INTERVENTION REQUIRED SM 2020 SERIAL WRITE DATA AS ASSEMBLED BY CONTROLLER DOUBLE FREQUENCY WRITE DATA FROM CONTROLLER NRZ WRITE amp READ CURRENT TO READ WRITE HEAD DOUBLE FREQUENCY READ DATA RAW DATA SERIAL READ DATA TO CONTROLLER 3 66 TRANSFORMATION FROM 1 Figure 3 3 WRITE FLOW DIAGRAM CONTROLLER SELECTS DRIVE WAIT READ 55 YES CONTROLLER COMMANDS NEW TRACK NUMBER CONTROLLER INACTIVATES WRITE GATE pr TRIGGER 25 uSEC READY ERASE GATE 5 DELAY ONE SHOT YES WAIT P
132. t Card No 2 figure 4 21 continued Reference Designator Part No Part Name Quantity U1 U2 U7 U8 17023 Integrated Circuit SN7407 4 U3 17055 Integrated Circuit 9602 1 04 60535 Integrated Circuit LM307N 1 05 06 60558 Integrated Circuit LM1458N 2 U9 U11 17002 Integrated Circuit SN7400 2 U10 17011 Integrated Circuit SN7474 1 CRO Qre2 10 ols 229 6 4 G 5 5 kok kino krok BBS EN o ule CE Ea 24 R22 CR3O CRE EH RAIN P CES US UO ER Figure 4 21 Servo Card No 2 73480 4 36 Disc Storage Unit Parts List for VFO Circuit Card figure 4 22 Reference Designator Part No Part Name D 73920 VFO assembly 73501 VFO circuit card C1 C9 12631 Capacitor DM15 220pf 500V C2 C5 C12 thru C20 12812 Capacitor CER 0 1uf 50V C3 12742 Capacitor 1500 iuf 50V C4 C6 12720 Capacitor 150D 6 8uf 20V C8 12738 Capacitor 150D 0 22uf 50V C10 12628 Capacitor DM15 160pf 500V C11 12814 Capacitor CER 0 22uf 50V C21 12605 Capacitor DM15 15pf 500V C22 12641 Capacitor DM15 500pf 500V CR1 CR2 CR3 13005 Diode 1N3064 CR4 13026 Diode 1N4736 6 8V 10 Q1 thru Q10 2191 Transistor MPS3640 011 12909 Transistor 284401 R1 R3 R8 R9 R16 R18 11132 Resistor RN55D 665 ohm 1 1 8w R2 R11 10054 Resistor RC07 1 6K 5 1 4w RA R6 R10 R15 R26 R27 10018 Resistor
133. the door so cartridge may be removed If the operator sets the power switch to POWER OFF and leaves the cartridge switch in the CARTRIDGE LOCK position the Power Function keeps power up for about two seconds to allow the carriage to be returned to home Under these circumstances there will be no power to unlock the door so the disc cartridge cannot be removed until after the front panel switches are set to CARTRIDGE UNLOCK and POWER ON If during normal operation the carriage is not positioned to the commanded track within 200 milliseconds the Start Stop and Status Function notifies the controller that the carriage is not at the commanded track The controller must then issue a new command to home and re seek Disc Storage Unit 5 2020 Section 2 OPERATION 2 1 SWITCHES 2 1 1 BACK PANEL POWER SWITCH The back panel power switch opens both input ac lines when off and connects both input ac lines to the Power Function when on 2 1 2 FRONT PANEL POWER SWITCH When the front panel power switch is in the POWER ON position the high ac line is connected to the power transformer and the cartridge motor switch It also applies ground to the cartridge switch for the motor switch on signal in the POWER ON position 2 1 3 CARTRIDGE MOTOR SWITCH When the cartridge switch is in the CARTRIDGE UNLOCK position and both power switches are in the on position the front door is unlocked and may be opened if the dc power is up and the dis
134. ting Screws 3 53 SM 2020 Disc Storage Unit 3 31 FIXED DISC ASSEMBLY REPLACEMENT Before replacing the fixed disc assembly thoroughly clean interior of drive by vacuuming first then wiping interior with alcohol dampened lintless cloth CAUTION Do not touch the surfaces of the disc Grasp the disc spindle by the shaft 1 Install the disc spindle through the top of the drive 2 Install the fixed disc sector pulley CAUTION Exercise care when installing the fixed disc cover to avoid contact between the spacers and disc surfaces 3 Align the four fixed disc cover spacers with chassis mounting holes Ensure that the carriage assembly is positioned against the rear crash stop Install fixed disc cover Temporarily tighten the four screws Connect B7 connector to drive control logic circuit card Connect the red leads to the appropriate microswitch contacts Connect the blue and violet leads to the appropriate solenoid contacts Connect the latch link from the solenoid to the fixed disc cover assembly O Install receiver assembly as follows a Align the two flange bearings with the receiver assembly mounting brackets and tighten the four screws b Align the microswitch on the fixed disc cover such that the microswitch contacts are made when the receiver assembly is in place c Install the two springs and four anchors 10 Slide fixed disc sector transducer all the way forward and tighten t
135. to the Start Stop and Status Function Set cylinder causes an active load cylinder register which loads the new address into the cylinder register When the new address is track 0 the cylinder register decode 0 signal is active high The new address is added to the present cylinder address counter contents and when the difference is other than 0 a shaped error signal is generated by the digital to analog converter on Servo Number Two card 3 6 Disc Storage Unit SM 2020 The address in the cylinder register is the binary number of the designated track The contents of the present cylinder address counter is the ones complement of the track number of the present head location When the commanded address is equal to the present head location all of the adder outputs are high and the drive forward signal is high The drive forward signal is exclusive ored with each bit from the adder so the outputs from the exclusive or gates are all low When the carriage is positioned so the heads are over track 0 the present cylinder address counter is set to all ones As the carriage moves forward count down pulses are generated in the head position control circuits and the present cylinder address counter counts down Any time a carry forward signal results from adding the outputs of the cylinder register and the present cylinder address counter the forward signal becomes the drive forward signal unless the carry borrow latch has been set by a carry fro
136. tor on that track The controller then selects the disc surface for a write operation by the appropriate select fixed disc and select lower head signal combination 2 zero is selected top surface of the removable disc when both signals igh Head one is selected bottom surface of the removable disc when select fixed disc is high and select lower head is low Head two is selected top surface of the fixed disc when select fixed disc is low and select lower head is high Head three is selected bottom surface of removable disc when both signals are a low When the appropriate sector passes under the read write heads the drive select and write gate signals from the controller are both active low enabling the write current generator Then double frequency write data from the controller causes the write current to the selected read write head to be alternated once for a zero and twice for a one When the designated track is greater than 256 128 for Model 2215 the write current is decreased by about 15 This maintains a recording level that compensates for the decrease in bit cell size as the heads are moved closer to the center of the disc Otherwise the read signal would constantly increase with higher track numbers and cross talk interference between tracks might become a problem When the write gate enables the write current generator it also enables the erase gate so a gutter is erased on both sides of the track figure
137. torage Unit 9 Q Y MM Chassis Assembly 73080 Partial Figure 4 10 4 21 SM 2020 Disc Storage Unit Parts List for Blower Assembly figure 4 11 Reference No Part Number Part Name Quantity 1 13838 Screw set 2 2 73261 Pulley 1 3 73405 Blower assembly I 1 AIR gt DISCHARGE Figure 4 11 Blower Assembly 73120 4 22 Disc Storage Unit SM 2020 Parts List for Transformer Assembly figure 4 12 Reference No Part Number Part Name Quantity 1 73211 Transformer 1 2 14961 Receptacle 5 QU R ORANGE 2 LENGTH 27 IN UR BLACK LENGTH 24 IN BROWN 2 LENGTH 25 IN Figure 4 12 Transformer Assembly 73420 SM 2020 Parts List for Prefilter Assembly figure 4 13 Reference No Part Number 13320 73081 73325 73324 PUNE Part Name Screw Base chassis Screen Plate prefilter Disc Storage Unit Quantity ft Ul 4 24 Figure 4 13 Prefilter Assembly 73130 Disc Storage Unit Parts List for Covers figure 4 14 Reference No Part Number 73295 19210 73150 73000 13316 18720 18723 73329 13320 0 73130 Os AWN Part Name Equipment cover Bumper Bezel assembly Base plate Screw Screw Screw Rear cover Screw Prefilter assembly Figure 4 14 Covers Package 73240 SM 2020 Quantity Q a DDR 4 25 SM 2020 Disc Storage Unit Parts List for
138. ued Step Procedure c Replace screen prefilter with P N 73325 d Reassemble prefilter assembly in the reverse order of removal 20 Inspect drive belt for evidence of wear or excessive stretch Replace worn belt 21 Attach drive control logic card to mounting bracket with four screws 22 Attach head connectors to Read Write circuit card 23 Insert all circuit cards in appropriate connectors 24 Replace head cable bracket and secure to drive chassis with two screws 25 Inspect interior for loose wire connections frayed wiring dirt or physical defects Vacuum interior of drive Tighten or repair loose connections and replace damaged components 26 Verify that all circuit cards are firmly seated 27 Verify that the head 0 through head 3 cable connectors are firmly seated in their respective JO through J3 positions of the Read Write circuit card 28 Inspect bottom of drive chassis for dirt or other contaminants loose wire connections frayed wiring and burnt or damaged components Vacuum bottom of drive Tighten or repair loose connections and replace damaged components 29 Replace bottom cover and secure with nine screws 30 Replace top cover and secure with six screws 31 Push drive into cabinet and tighten two captive mounting screws Table 3 2 Twelve Month Preventive Maintenance Step Procedure 1 Perform six month preventive maintenance to step 20 Adjust drive belt tension a Remove two scre
139. uld drop below 70 nominal or ac power is lost either because the back panel power switch is set to off or because ac to the drive fails Kl on the power supply will be deenergized and the drive home amplifier will apply reverse drive to the actuator to retract the heads 3 7 SECTOR AND SPEED DETECTION FUNCTION figure 3 38 When the spin motor is turned on the discs start to rotate The fixed disc hub has 48 sector notches and one index notch and the removable disc skirt has 47 sector notches and one index notch An optical detector for each disc generates a signal for each notch that passes the detector These detected notch signals are used by the circuits on the interface board to generate the sector pulses and index pulses for the fixed and removable discs The fixed disc notch detected signal triggers a 620 microsecond delay one shot When the next notch is detected before the one shot times out the pulse for that notch triggers a 5 microsecond one shot whose output is the fixed disc index pulse Each time the 620 microsecond delay one shot is triggered it triggers a 5 microsecond one shot whose output is the fixed disc sector pulse Each fixed disc sector pulse triggers a retriggerable 2 2 second one shot The Q output of the 2 2 second one shot spin stopped is always low when the next sector pulse occurs oftener than every 2 2 seconds When fixed disc sector pulses are less frequent than every 2 2 seconds the spin stopped signal bec
140. used Screw Shim Disc Storage Unit Quantity RON Rn EPR ARERR r SM 2020 Disc Storage Unit Door Assembly 73160 Figure 4 5 4 11 SM 2020 Parts List for Chassis Assembly figure 4 6 00 1 Ov gt GQ N Reference No Part Number 13366 B73020 73720 13331 18763 13612 73401 73367 73366 10 13313 11 74354 12 26601 13 25500 14 18510 15 A73080 E73080 16 14122 17 19262 18 73280 19 60049 20 73273 21 73135 22 13316 23 74354 24 13335 25 K8140 H8140 26 J8140 G8140 Part Name Screw Actuator Drive control logic circuit card Screw Washer nylon Screw Spin motor assembly Mounting block head lead Bracket Screw Card separator 2 card Bushing Foam tape Snap bushing Chassis assembly 115V 60Hz Chassis assembly 220V 50Hz Nut Grommet Locking latch assembly Tape Bracket Cam Screw Card separator 3 card Screw Lower head 100 TPI Lower head 200 TPI Upper head 100 TPI Upper head 200 TPI Disc Storage Unit Quantity gt RN BREE PN HH IN t gt EA A HA HH HC Disc Storage Unit SM 2020 FROM POWER SUPPLY FROM ACTUATOR ASM TO POWER SUPPLY N 0 RED FROM SW CONT L PANEL GREY AND VIOLET FROM SW CONT L PANEL SW CONT L PANEL Figure 4 6 Chassis Assembly 73080 Top View SM 2020 Parts List for Actuator Assembly Top View figure 4 7 Reference No Part
141. ws securing switch fuse assembly to drive chassis figure 3 5 Position switch fuse assembly such that spin motor mount is accessible figure 3 6 Disc Storage Unit SM 2020 Table 3 2 Twelve Month Preventive Maintenance continued SWITCH FUSE MOUNTING SCREWS CONNECTOR MOUNTING PLATE Figure 3 5 Switch Fuse Assembly Mounting Screw Location b Loosen three screws holding the spin motor mounting plate to the drive chassis figure 3 6 FILTER SCREWS 1 OF 9 Figure 3 6 Spin Motor Mounting Plate Location Temporarily install switch fuse assembly Ensure that the drive is in an upright position SM 2020 Disc Storage Unit Table 3 2 Twelve Month Preventive Maintenance continued d Place the drive in normal operation by setting ac switch to ON position the power switch to POWER ON and the spin motor switch to CARTRIDGE LOCK position e Verify that the belt tension spring automatically shifts the motor to the correct belt tension f Remove power by setting the spin motor switch to CARTRIDGE UNLOCK position power switch to POWER OFF and ac switch to OFF position g Remove two screws securing switch fuse assembly to drive chassis h Retighten the three mounting screws holding the drive motor mounting plate to the drive chassis i Install switch fuse assembly 3 Replace the absolute filter a Remove nine screws securing air filter to bottom of drive chassis Remove air filter figure 5 7
142. y against rear crash stop insert head spacers between the removable disc heads and the fixed disc heads figure 3 2 11 Remove screw mounting front of actuator frame to drive chassis figure 3 11 12 Position carriage forward until rear mounting screw is accessible and remove mounting screw figure 3 26 13 Slide entire actuator assembly towards rear of drive NOTE Actuator must be held in erect position to prevent it from tipping over 14 Disconnect connector B4 from drive control logic card figure 3 25 15 Pull red and black leads from dc motor through access hole and remove actuator assembly from drive CONNECTOR B4 FROM CONNECTOR B3 FROM OPTICAL POSITIONING SWITCH PANEL TRANSDUCER CONNECTOR B7 FROM CONNECTOR B6 FROM REMOVABLE DISC FIXED DISC SECTOR CONNECTOR B5 FROM SECTOR TRANSDUCER TRANSDUCER POWER SUPPLY Figure 3 25 Drive Control Logic Circuit Card Connector Location 3 44 Disc Storage Unit SM 2020 3 23 ACTUATOR ASSEMBLY REPLACEMENT 1 Perform in reverse order steps 6 through 15 of paragraph 3 22 NOTE The actuator assembly is properly aligned when the actuator frame is positioned against the two alignment pins 2 Verify correct alignment of the optical positioning transducer block assembly shutter assembly and removable disc heads 3 24 OPTICAL POSITIONING TRANSDUCER REMOVAL Remove disc cartridge from drive Remove drive power and extend drive to obtain access to back of drive 3 Perf

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