Seagate ST506 Manual 1982
Contents
1. a N N N 30 31 32 33 34 35 OO bet N 36 37 2 38 39 40 41 42 mW N Seagate Technology e 9 e e J 4 a eee P e ST 506 Service Manual P N 20019 TPQ3904 4120 v 6330 1 7408 74123 74S74 7406 74LS221 7445 26LS32 74S86 7410 7438 2074 74191 7400 7402 741514 7407 7404 592 261531 IM339 PACK 220 330 OM SHUNT 7 POS AMP 435704 7 C gt 3 4 CAP CAP CAP CAP CAP CAP CAP CAP gt CAP SOCKET 16 PIN SOCKET 14 PIN ELECTROLYTIC 22uf 16V TANT 4 7uf 35V 10 CERAMIC 150pf NPO 59 CERAMIC 033uf X7R 109 CERAMIC 100pf NPO 59 CERAMIC 330pf NPO 5 CERAMIC 470pf NPO 5 CERAMIC luf Z5U 80 20 PCLYCARB 1uf 50V 10 DICDE 1N4148 DICDE 1N4003 DICDE ZENER 4 3V 1N5229B INDUCICR 2 2uh INDUCTOR 10uh INDUCTOR 3 3uh PAGE 48 Location 2E 2G IR 2 52 10 3C 2A 3A 6H 3D 4D 2D 6F 6D 2 5C 5D 2F 2H 1C 4C 4B 1B 5B 6E 5H 3B 3E 5F 6G 4 6 6 6 6B C27 14 15 22 25 28 29 42 17 24 21 C8 C10 C202. OUT ENA 9K COMP w READY w ACTNITY LED 568 ACTNITY LED MUST CONFORM TO ENGINEERING PEC PHASE A RH 2 7 9 4 1 2 13 gt x lt Q 5 220K R91 HOK R90 47K 5 VEU AAA RBO 2K 275 2 25 4 7 TRACC ee SEEK COMPLETE A y READY 19 c NOTES UNLESS OTHERWISE SPECIFIED l RESISTANCE VALUES IN OHMS 4 W 590 LOCATION ALL 1 GESHTORS Ve W 5464 D GO z 3 CAPACITANCE VALUES IN MICZOFARADS 80 20 TT DODES ARG 1 0 lO A 5 INDICATES CONNELTO JI COA 12 VA S AP INDICATES CONNECTOR J2 THEU 38 48 49 7 9 INDICATES TEST POINT PINS 8 NOT INSTALLED 9 POLYCARBONATE SOV 110 OV 1 29 cao caza 1 25 19 4 29455 9 0 12 14 17 TALS 221 al 7445 2 4 0 6 12 S 15 10 19 20 20004 60 l Zio CI 50 E2 2220 44 IN4JOOS Ses 525 415 O 29 041 5 AI 7 5 48 IOK 21 ga 226 Sion acm NOTES UNLESS OTHERWISE SPECIFIED
3. L _ 3 0ms _ TEST POINT 1 i j NN 3 0ms eT TEST POINT 2 TEST POINT 4 200us typ 16 67ms 1 TEST POINT 1 500ns typ TEST POINT 5 NOM typ 24 FIGURE 3 1 TEST POINT 1 STEP PULSE J FIGURE 3 2 TEST POINT 2 STEP TIMING FIGURE 3 3 TEST POINT 4 INDEX SENSOR FIGURE 3 4 TEST POINT 5 SEEK COMPLETE TIMER TEST POINT TIMING TEST POINTS 7 amp 8 250 typ LELELEEELEELEELT ETE T LL FIGURE 3 9 TEST POINTS 7 amp 8 x DIFFERENTIAL READ FILTER 200 ns a TEST POINT 11 77773 200ns 50 60ns FIGURE 3 6 TEST POINTS 11 amp 13 TIME DOMAIN FILTER TEST POINT 13 PAGE 25 TEST POINT LAYOUT P C B P N 20019 PAGE 26 TEST POINT LAYOUT P N 20040 14 BE PAGE 27 12 RENE LED E Theory of Operations ST 506 Service Manual 2 5 ST 506 Schematics Main Control P C B P N 20019 Main Control P C B P N 20040 Motor Control P C B P N 20003 Seagate Technology PAGE 28 5 1 82 8 6 E m 55388 q NEN NUN d sh mom P DIRECTION 24 DIRECTION 53 HEAD lt 29 541 HEAD SEL 2 312 WRITE CATE 2V 2 29 aut OC wPITE DATA WRITE DATA COMPLETE v READY A SEAGATE MUST
4. 2 1 5 Air Filtration System All drives manufactured by Seagate Technology incorporate an integral air filtration system No maintenance or adjustments are needed throughout the life of the drive The integral 0 3 micron air filter performs two functions First the filter maintains Class 100 standards inside the sealed Head Disc Assembly througbout the life of the drive Second an auxillary port allows pressure equalization with ambient air During normal operation there is no measurable air flow between the HDA and the outside environment Seagate Technology PAGE 6 5 1 82 Theory of Operations ST 506 Service Manual 2 2 Mechanical 2 2 1 Track g Sensor The Track optical interrupter provides an output whenever the Winchester heads are positioned over cylinder g This signal is used by the internal drive control electronics during the power on auto recalibrate routine The Track signal is also output to the drive interface for use by the controller Note that the signal at the interface is really Track f Phase A The Track f optical interrupter incorporates an infrared light emitting diode and an infrared sensitive photo transistor When the heads are positioned at cylinder f an interrupter arm attached to the stepper motor shaft mechanically breaks the light beam between the two components of the sensor The sensor will output a valid Track g signal as long as the light beam remains broken 2 2 2 Index Sensor The In
5. is of a Gabber cork composition with wear life designed to exceed 20 000 cycles When energized the brake wil draw a maximum current of 267 milliamps MEME The brake must be adjusted so that the contour of the pad contact matches the spindle motor hub When disengaged the dimension between the spindle motor hub and the Bae contact should be set at 10 mils Seagate Technology PAGE 8 5 1 82 Theory of Operations ST 506 Service Manual 2 3 Electrical Theory Flowchart 2 3 1 Motor Speed Control Block Diagram pee COMPARATOR F1 STARTER H INTEGRATCR lac decli Functional D escription Initially when power is first applied the disk is stationary and the Hall effect transistor will output a high or low level depending on the physical position of the motor This DC level wil keep Q1 turned off allowing C5 to charge up Pin 1 of Comparator A2 will output a low level that travels through R12 and forces pin 7 of A2 high As a result Al wil be off and maximum current wil flow into the coil selected by the level of the Hall effect sensor As the motor speeds up the Hall effect becomes a square wave responsible for both selecting the motor coil to receive current and controlling the amount of current applied Current is supplied alternately to coils A and B as the Hall device senses the motors physical position Depending on the time between high going edges of the Hall effect sensor Q1 will be turned off lon
6. 2 3 3 Drive Selection 997999 e e e o pG T o 13 TABLE OF CONTENTS SECTION PAGE 25256 Step Cpetatiot s a usss e 14 2 3 5 Read Operation aassasasssassas sss 25346 Write 100 ease EE ees 19 2 4 Test Point Descriptions ons geese se be twa ua 22 249 SCHEMATICS wales wine eis Mis Dane 528 3 0 55 34 54 5 4 4 45 8 5 26 3 1 DA Ba 3 2 Removals And Adjustments e ccevccccncccsesecvceseucscess3S 3 2 1 Mann Control P G B uses eese e aa sessaeesUsxiO 3 2 2 Motor Control 35 3 2 3 Spindle PEA 3 2 4 Index asas A 3 2 5 Ground 3826 Track g Sensor vu su yy k 27 3 2 7 Front CEP ncs LIE UD s usss 3 2 8 Front Cover ER 35249 SIGE BEANE 4 0 ILLUSTRATED PARTS rica u auqa 7 4 1 Physical Locations usd side ween eres See veros 4 1 1 Drive Exploded 4 1 2 Connectors Exploded View 42 4 2 Component Locations TABLE OF CONTENTS SECTION PAGE 4 2 1 Main Control P C B P N 20019 44 4 2
7. ALL RESISTORS ARE IN OHMS LAW 5 2 ALL CAPACITORS IN MICROFARADS 10 3 INDICATES JI 4 INDICATES J2 C5 POLYCARBONATE 50V 10 TOLERANCE UNLESS OTHERWISE NOTED LINEAR CORNERS OUTSIOE MAX i PART NO BROKEN INSIDE MAX 20002 001 Maintenanc e R epair ST 506 Service Manual 3 0 MAINTENANCE REPAIR 3 1 Introduction The Seagate Technology ST 506 Microwinchester disc drive does not require preventive maintenance Additionally all units shipped are covered by a one year factory warranty If field maintenance or repair is required certain restrictions apply Primarily the environmentally sealed Head Disc Assembly HDA must not be opened Seagate Technology considers a drive to be out of warranty if the HDA has been tampered with Any special tools or additional restictions will be covered under the appropriate sections This section of the ST 506 Service Manual will attempt to cover adjustments and repair of the field serviceable portion of the disc drive Any questions that are not covered in this document should be referred to the Technical Support department at Seagate Technology Seagate Technology PAGE 34 5 1 82 Maintenance R epair ST 506 Service Manual 3 2 Removals Adjustments Note Removal of any assembly not covered in this section is not possible without special clean room facilities and tools 232 1 Main Control P C B 002 T
8. ER TRK O SENSOR ASSY s GND SPRING ASSY Ix BASE CASTING REFERENCE DESCRIPTION PART NO REMARKS SEAGATE TECHNOLOGY w DRIVE EXPLODED AH ORIVE VIEW MAX MAX E CEOE EESE s _ 1 BRUSHLESS D C MOTOR CABLE L E D CABLE STEPPER MOTOR CABLE P8 TO CONNECTOR J8 CONTROL OPTICAL INTERRUPTER CABLE PT gt CONNECTOR J 7 CONTROL MTR POWER CABLE P4 TO CONNECTOR 74 CONTROL P C B pow INDEX SENSOR CABLE PG TO CONNECTOR JG CONTROL PRINTEO CIRCUIT CABLE P5 TO CONNECTOR J5 CONTROL PC B SPINDLE BRAKE CABLE TOLERANCE UNLESS OTHERWISE NOTED XX LINEAR XXX HARDNESS SURFACE TREATMENT toar Illustrated Parts Catalog ST 506 Service Manual 4 2 Component Locations 4 2 1 Main Control P C B P N 20019 4 2 2 Main Control P C B P N 20040 4 2 3 Motor Control P C B P N 20003 Seagate Technology PAGE 43 5 1 82 2 gt 0 O l Z I H H L 0 52 OF SHEET m lt e ces Le 0000000 0000000 m o iva jo oot cone 99999996 a o o 0 qv o m 2 00900008 00000060 66000000 E enc me 0197519 co 0000008 oo000008 o00000 98 o o fae 0000000 o 5586626 0000000095
9. 1 82 Illustrated Parts Catalog 4 3 3 Motor Control NA VA RW DN G a t ES DO NO IRI M de Seagate Technology P N 20003 Description TRANS ARRAY CR 006 1 358 ULN2074B CAP PCLYCARB luf 50V 10 CAP ALUM ELECT 150uf 25V ELECT 22uf 16V CAP CERAMIC CAP CERAMIC CAP CERAMIC CAP CERAMIC CAP CERAMIC CAP ALUM 0047uf XIR 047uf X7R 068uf X7R 001uf X7R DIG 1N4005 DICDE ZENER DICDE 1N4148 TRANSISTCR 2N3904 RESISTOR 1 4W 5 RESISTOR 1 4W 5 DECTCTYD 1 AW ELAS THT 2 0 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 2W 2 RESISTOR 3 4W 10 50K HEADER 6 PIN HEADER 2 PIN PLUG 6 2V luf 250 15234 10 47 470 1 5 20K 510K 100K 1 2 MEG 4 7 130 CM ZW 5 20 ST 506 Service Manual Location Al A2 A3 C5 Cl C2 C3 4 C6 7 C8 C10 C9 11 12 1 2 Q1 R2 11 R4 9 R5 8 R6 R7 16 R10 R12 R13 R15 R17 20 R1 R18 19 R3 11 2 4 5 1 82 Illustrated Parts Catalog ST 506 Service Manual 4 3 4 Spare Parts List 1 1 Motor Control P C B Assembly 20003 001 2 1 Main Control P C
10. B Assembly 20040 001 3 1 Spindle Brake Assembly 54026 001 4 1 Index LED Assembly 54037 001 5 1 Ground Spring Assembly 58061 001 6 4 Shock Mount 52025 00601 7 4 Shock Mount Spacer 58023 156 8 4 Shock Mount Washer 16527 006 9 1 Track g Sensor Optical Inter 12616 001 10 1 Left Side Frame 64023 001 11 1 Right Side Frame 64024 001 12 1 Eront Cover 62018 001 13 1 Eront Cover LED 10850 003 14 1 Front Cover LED Grammet 13025 001 15 1 DIP Shunt 7 Position 11825 007 Seagate Technology PAGE 53 5 1 82
11. R14 R5 6 7 8 21 24 29 38 R15 27 28 45 46 R39 53 R18 31 32 52 58 59 62 64 66 75 78 79 81 89 90 97 102 104 R16 17 26 R30 R76 R43 69 82 84 88 R9 12 47 60 61 71 77 R70 68 73 83 R74 R105 108 INSULATOR 5 THERMALLOY 4005 15 Q1 2 3 HEADER 16 PIN 86479 2 HEADER 5 640457 5 HEADER 2 PIN 350209 1 HEADER 4 PIN 350211 1 POST 025 SQUARE POT 3 4W 10 50K PAGE 49 J5 16 7 8 J4 J3 TP1 15 R63 5 1 82 Illustrated Parts Catalog ST 506 Service Manual 8 29 16 23 30 4 3 2 Main Control P C B P N 20040 Item No Quantity Description Location 1 2 I C TPQ3904 1C ID 2 1 I C 4020 2B 3 1 I C 6330 1 2D 4 1 I C 7408 5B 5 1 74123 6 2 74574 3B 6H 7 1 1 7406 4 8 1 I C 7415221 4E 9 1 I C 7445 10 1 261532 11 1 1 74586 5 12 1 I C 7410 74810 741510 3C 13 2 I C 7438 50 60 14 2 2074 1B 1E 15 1 I C 74191 2C 16 1 I C 7400 74S00 41500 4 17 1 7402 74502 741502 3D 18 3 741514 5C 2E 6E 19 1 7407 5H 20 1 7404 74504 CR 74LS04 4D 21 1 I C NE592 5 22 1 261 531 6E 23 1 1 1 339 4A 24 1 R PACK 220 330 GM 6C 25 1 SHUNT 7 POS AMP 435704 7 6B 26 1 TRANS ARRAY 2907 CR SALONE 4H 27 1 I C SOCKET 16 PIN 6B 28 1 I C SOCKET 14 PIN 6C 29 1 CAP CERAMIC 047uf X7R 10 C4 230 1 CERAMIC 33p
12. Sectors per Track Access Time Track to Track Average Max imum Settling Time ST 506 Service Manual 1 per 1010 bits read 1 1012 bits read 1 106 seeks 16 retries 6 38 Megabytes 1 59 Megabytes 10416 Bytes 5 0 Megabytes 1 25 Megabytes 8192 Bytes 256 Bytes 32 3 milliseconds 170 milliseconds 500 milliseconds 15 milliseconds typical Reducible to 85 ms using fast seek algorithm Reducible to 205 ms using fast seek algorithm Transfer Rate Average Latency 1 2 4 Functional Specifications Rotational Speed Recording Density Flux Density 5 0 Megabits per second 8 33 milliseconds 3600 RPM 1 7690 BPI Maximum 7690 ECI Maximum Track Density 255 TPI Cylinders 153 Tracks 612 Read Write Heads 4 Discs 2 Seagate Technology PAGE 3 5 1 82 Theory of Operations ST 506 Service Manual 2 0 THEORY OF OPERATIONS 2 1 General 2 1 1 Recording Format The ST 506 uses modified frequency modulation MEM as the encoding method implemented to record data on the drive This double density encoding scheme increases disc data capacity by replacing clock bits with data bits Clock bits are written only when data bits are not present in both the preceding and the current bit cell Clock bits are written at the beginning of the bit cell while data bits are written in the middie Due to predictable bit shift phenomena write data may require precompensation This function must be pr
13. e ig 9 6 St2 o EE LE o0000009HN o of e 9 ses R zs ba az 06000000 00000000 o0000000 0 ELD e 745 Le 9 229 z 00000008 9722 5 4 2 1 MAIN CONTROL P C B P N 20019 FITLE DAME AA 39Vd oa 4 234 00000900 lt 002 N d 82d OHINOO NIVW Z p SILL 000906 e e 4 7 M D n 4 m m I Z D lt 2 eT So oT 2 e o e e ee IM za Je e 02 ae e m RAI Re 55 QIN Re 4 SEAGATE TECHNOLOGY OF SHEET TITLE 4 2 3 MOTOR CONTROL P C B P N 20003 PAGE 46 Dlustrated Parts Catalog ST 506 Service Manual 4 3 Parts Lists 4 3 1 Main Control P C B P N 20019 4 3 2 Main Control P C B P N 20040 4 3 3 Motor Control P C B P N 20003 4 2 4 Spare Parts List Seagate Technology PAGE 47 5 1 82 Illustrated Parts Catalog 4 3 1 Main Control P C B NO 00 ION VA AWN i U h3 C N N No KH bho fO NH A 55 REI de M OV V WW EA o G6 w a N
14. 1 2 1 Physical Specifications Environmental Limits Ambient Temperature Operating Non operating Temperature Gradient Operating Non operating Relative Humidity Maximum elevation Operating Non operating Shock Operating RT _ 2 5 1NQ1 OD C L at ing D C Power Requirements 12V 35 1 8A Typical 5V 35 7A Typical Maximum Ripple Mechanical Dimensions Height Width Depth Weight Shipping Weight Heat Dissipation Typical Maximum 1 2 2 Reliability Specifications MIBE PM Component design life Seagate Technology PAGE 2 ST 506 Service Manual 40 to 1229 E 49 to 50 40 to 140 E 409 to 60 C 189 F Hour 10 Below condensation 8 to 80 Non condensing 10 000 Eeet Eo x 1000 to 30 000 Feet 10G s On side frames ne Ze EE LUU 5 S1G 5 4 5A At power 1 0A Maximum 50mv peak to peak 12 5 3 25 Inches 5 75 Inches 8 00 Inches 4 6 Pounds 2 1Kg 7 0 Pounds 3 2Kg 25 Watts 29 Watts 11 000 Typical usage 30 Minutes Not required 5 Years 5 1 82 Introduction Error Rates Soft Read Errors Hard Read Errors Seek Errors Not recoverable within 1 2 3 Performance Specifications Capacity Unformatted Per Drive Per Surface Per Track Formatted Per Drive Per Surface Per Track Per Sector
15. 1 6 11 13 16 18 19 26 30 41 43 44 45 C23 CR1 17 23 30 CR19 22 CR18 L1 2 L3 4 6 L5 5 1 82 Illustrated Parts Catalog to WwW ON to ut F4 AH vw bt Ae t IE AN ER bh fb fo uw U 43 44 45 46 47 48 49 50 51 52 53 54 55 56 K Ji 58 59 61 62 63 64 65 66 67 68 69 70 71 72 73 74 76 77 78 79 80 VS Q Seagate Technol ogy escriptj TRANSISTOR 2N3468 TRANSISTOR 2N3904 RESISTOR 1 8W 1 RESISTOR 1 8W 1 RESISTOR 1 8W 1 RESISTOR 1 8W 1 RESISTOR 1 8W 1 RESISTOR 1 8W 1 RESISTOR i 8W 1 RESISTOR 1 8W 1 RESISTOR 1 8W 1 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 90 9 QM 100 GM 162 CHM 178 221 909 ik 4 64 7 68 9 1K 22 47 OM 100 150 GM 220 270 330 GM 470 620 1 5 2K 2 7K 4 7K 10K 15K 100K 47K 10 GM ST 506 Service Manual R36 37 R48 50 55 R35 R49 51 R80 R98 99 100 101 R33 54 R13 25 34 R67 72 R1 2 3 4
16. 2 Main Control P C B P N 20040 45 4 2 3 Motor Control P C B P N 20003 46 RECETA WA du S E NS e dx 4 3 1 Main Control P C B P N 20019 48 4 3 2 Main Control P C B P N 20040 50 4 3 3 Motor Control P C B P N 20003 52 4 3 4 Spare Parts sas LIST OF ILLUSTRATIONS 2 1 Track Fom Oe crt Seen zy Sama za sus 2 2 Test Point 1 2 3 Test Point 2 00 2 4 Test Point 4 Timing 24 205 Test Point 3 Timing 2 6 Test Point 7 and 8 2 7 Test Point 11 and i3 Timing 25 2 8 Test Point Layout P N 20019 20 2 9 Test Point Layout P C B P N 20040 Cee Ea REV LIST OF TABLES 2 1 Step Pulse Encoding Phase Sequencing ccccccccccccccscccceceeel6 Introduction ST 506 Service Manual 1 0 INTRODUCTION 1 1 General Description The ST 506 disc drive is a random access storage device with two non removable 5 1 4 inch discs as storage media Each disc surface empleys one moveable head to service 153 data tracks The total formatted capacity of the four heads and surfaces is 5 megabytes 32 sectors per track 256 bytes per sector 612 tracks Up to four drives may be daisy chain connected in one s
17. CONFORM TO ENGINEERING BPEC TOLERANCE UNLEGS OTHERWIBE NOTED DIRECTION T 8 7 6 5 _ 4 IEEE DRE di cmm 7P OTEP OUT 2 412 SEEK COMPLETE HEADY READY INOE X A OTE FAULT PU PENES go 2 L OK Gs 02 a4 q gt 3 272 60 5 NOTES UNLESS OTHEEWIGE SPECIFIED 2EEISTANCE VALVES ARE IN OHMS 4 4 5 2 2ZEGISTORS 6 a CAPACITANCE IN 4 MODES 5 INDICATES CONNECTOR JI n SE S LA NIS A INOCATEG CONNECTOR JZ Theu Je 273 L 4 INDICATES TEST POINT PINS z 3 2 PART NOT NSTALLEO TPO 214 Apya B E74 47K GND 4 6 8 u 2 Agen STEP ST DICECTION 221 Y 50 STEP dz DIRECTION 34 LI 7 HEAD seu 2 x dix P 22 LANA 3 HEAD ez 2 e gt AAA 3 ca CONS 3 4 Sm 9 9 i it eretar E u 1 8 52 am ae a SING 021 2 5 PEDUCED JWR x D 9 ae 1 1 1 5 7 on E ee u L e JIA gt o ov ay x 4 87 ce w FAULT 5 1 330 5 2 4T 620 aw x
18. Head selected for read during write 4 Head selected for write during read The above circuit constantly sums the head center tap voltage If the voltage exceeds the upper or lower threshold established by the resistor divider the circuit provides a Head Unsafe output The upper and lower thresholds shift correspondingly when Write Gate is active A capacitor delays this change to allow for the change from read to write If any unsafe condition is sensed the Write Fault line is activated and 12V is removed from the write circuit Seagate Technology PAGE 20 5 1 82 Theory of Operations ST 506 Service Manual If the DC power degrades by more than 20 the power unsafe detector circuit will select a nonexistant head activate Write Fault turn off write current and initiate a recalibration sequence Plus 5 volts dropping below 4 volts will force the 5 volt comparator to a high level Plus 12 volts dropping below 10 volts will force the 12 volt comparator to a high level When either comparator turns on the resulting low level is gated through to the head select decoder and output to the drive interface as an active Write Fault signal A low voltage fault condition will also turn off the write current source Additionally this fault condition will reset the up to speed and recalibration latches initiating an auto recalibration sequence Write Gate and write current are continuously tested If one is ever active when the other is not a f
19. MHz should be observed full track record of high frequency data 000 or 1111 should resemble figure 3 5 Test Points 11 and 13 Time Domain Filter Test Points 11 and 13 may be used to observe the operation of the Time Domain Filter Trigger on Test Point 11 and monitor the delay at Test Point 13 Typically the delay observed should be 50 to 60 nanoseconds A full track record of high frequency data 000 1111 should resemble Rie 2 eVe st Poi Test Point 15 may be used to force the drive outward past Track g Grounding this test point defeats the crash stop prevention circuitry and allows the additional stepper motor travel This is a convenience feature for use in the drive manufacturing process Note Improper use of this function may permanently damage the drive Test Point 16 Half Step Note This test point applies to Main Control P C B P N 20040 and greater Test Point 16 may be used to temporarily activate the Half Step option Grounding this test point performs the same function as activating the Half Step option at position 6B 6C on P C B P N 20019 This is a convenience feature for use in the drive manufacturing process Test Points 9 10 12 and 14 Convenience Ground For any of the above functions use the ground test point that is in closest proximity to the active test point Seagate Technology PAGE 23 5 1 82 TEST POINT TIMING TEST POINT 1
20. SEAGATE TECHNOLOGY ST 506 MICROWIN CHESTER SERVICE MANUAL MAY 1 1982 360 El Pueblo Road Scotts Valley CA 95066 Phone 408 438 6550 TABLE OF CONTENTS SECTION PAGE 1 0 JNIBCBUETIION G 4er d eo win See vise 1 1 General 1 2 Specification SUMS LV dase shew es 1 2 10 Phy Steal co fine owes wae 1 2 2 Reliability TA 12 2 Perfois ance l s us ve EE e saxa ukyaq 1 2 4 Eunetronglz CREER SOT sv vd 2 0 THERY CE CPERATICNS 4 Zeb General reed sees 2 1 1 Recording ERR casaig 2 1 2 Track 2 1 3 Winchester 2 1 4 Discs S 2 1 5 Air Filtration System Seo sees 2 2 Mechanical 2522 Track nc u 2 2 2 Index 2 2527 Ground Spring soriga resent 2 2 4 Spindle E can 2 2 Electrical Iheory Elowchatt o 44a A ee 2 3 1 Motor Speed Control 9 2 3 2 Auto Recalibration o ioco paw awa oae yn aL
21. W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 HEADER 16 PIN AMP 1 5K 162 178 CM 57 6 OM 825 1K 4 87 7 68 390 560 GM 12K 22 GM 47 100 GM I en CLA 42 750 GM 270 QM 330 QM 470 CM 620 1K 1 5K 2K 4 7K 10K 15K 2 7K 100K 47K 10 GM 1 2K 220 CM 680 86479 2 HEADER 5 PIN AMP 640457 5 HEADER 2 PIN AMP 350209 1 HEADER 4 PIN AMP 350211 1 POST 025 SQUARE 3 4W 10 50K RES 8 SIP 2 2K RES PACK 8 PIN SIP 47 PAGE 51 ST 506 Service Manual Location 11 2 13 4 6 L5 CR1 10 13 14 32 33 04 5 6 7 16 17 19 20 R22 23 R44 R58 R48 50 57 R35 R49 51 R42 R1 2 3 4 R80 R98 99 100 101 R33 54 R25 34 40 41 R12 67 72 R88 R14 84 R21 24 29 38 83 R15 27 28 45 46 56 R39 53 R18 31 32 52 55 62 64 66 75 78 79 81 89 102 103 R26 R30 R43 69 85 87 R9 12 47 61 71 77 R60 70 R76 R59 68 73 R74 90 R105 108 R5 6 7 8 R82 R36 37 J5 J6 7 8 J4 J3 TP1 16 R63 RP1 4 RP2 3 5
22. ace Approximately 15 milliseconds later the seek complete timer will cause the Seek Complete signal to go true Seagate Technology PAGE11 5 1 82 Theory of Operations ST 506 Service Manual The active state of Seek Complete is a signal to the controller that normal operations can begin The up to speed and recalibration latches will stay set until power is interrupted or drops more than 20 below normal If this occurs the recalibration sequence will again be initiated Seagate Technology PAGE 12 5 1 82 Theory of Operations 2 3 3 Drive Selection Block Diagram LINE RECEIVER fran interface STEP PULSES from interface DRIVE SELECT 1 DRIVE SELECT 2 DRIVE SELECT 3 DRIVE SELECT 4 WRITE GATE fram interface WRITE DATA from interface ACTIVITY LED internal Functional D escription Drive Select serves only to gate other ST 506 Service Manual LINE DRIVER to interface DRIVE SELECTED to interface TRACK f to interface READY to interface to interface WRITE FAULT to interface INDEX to interface signals to or from the drive interface Without Drive Select the drive cannot read write or seek Seagate Technology PAGE 13 5 1 82 Theory of DIRECTICN Operations ST 506 Service Manual 2 3 4 Step Operation Block Diagram Functional D escription In order to step the following condit
23. ault condition will occur This signal is gated to the drive interface and head select decoder It will also be gated to turn off the write current source In addition to the three above listed fault conditions Write Gate is compared with Drive Select Seek Complete and Ready If an improper condition exists with any of these signals write current will be shut off Seagate Technology PAGE 21 5 1 82 Theory of Operations ST 506 Service Manual 2 4 Test Point Description est Poi c Test Point 1 may be used to monitor the interface step pulses Only the trailing edge of the pulse may be considered valid transition from negative to positive If step pulses are issued at a 3 0 millisecond rate the signal at Test Point 1 should resemble Figure 3 1 est Poi Tj Test Point 2 may be used to monitor the internal step circuitry For each step pulse on the interface Test Point 1 two step pulses must seen at Test Point 2 Note that if the Half Step En option is activated the second internal put will be defeated To adus the imc step circuitry trigger on Test Point 1 and adjust R63 for a delay of 2 8 milliseconds 0 0 05 at Test Point 2 Only the trailing edge of the pulses may be considered valid If step pulses are issued at a 3 0 millisecond rate the signal at Test Point 2 should resemble Figure 3 2 est Poi ero Sen Test Point 3 may be used to monitor the Track Zero sensor A low logic level is a valid Track Zero i
24. d in for at least 12 hours to settle the capacitor before adjusting the speed Seagate Technology PAGE 35 5 1 82 Maintenance R epair ST 506 Service Manual 3 2 3__Spindle Brake Tools Required 5 64 Hex Driver Loctite 242 10 Mil Shim 010 Flexible 1 Remove 4 6 32 x 1 4 Main Control mounting srews 2 Disconnect 1 through P8 noting their positions 3 Slide the Main Control P C B toward the rear of the drive and remove 4 Disconnect P2 at the Motor Control P C B and free the brake wires from the retaining clip 5 Remove i 6 32 x i brake mounting screw washer and spacer 6 Remove the brake solenoid 7 To reinstall apply Loctite to the first 3 threads of the brake mounting screw Replace the brake solenoid spacer washer and mounting screw but do not tighten 8 Insert the flexible 10 mil shim between the brake pad and the spindle motor housing 9 Move the brake toward the spindle motor housing until the solenoid spring assembly is compressed and a slight resistance is felt on the shim 10 Tighten the 6 32 brake mounting screw and verify that the contour of the brake pad aligns with the spindle motor housing 11 Route the brake solenoid wires through the retaining clip and connect P2 to the Motor Control P C B 12 Reverse steps 1 through 3 to replace the Main Control using Loctite on the first 3 threads of all 6 32 screws 2 2 4 Index Sensor Tools Required 5 64 Hex Drive
25. dex sensor provides an index pulse to the recalibration circuit and to the interface of the ST 506 drive Once each revolution 16 67 ms the Index sensor outputs a pulse that is typically 200 microseconds in width The Index sensor used on the ST 506 drive is of the reluctance transducer type This cylindrical sensor incorporates a built in preamplifier The case of the sensor is grounded electrically which ties the drive DC returns to the drive casting The hub of the spindle motor has two metal tabs attached one is of a ferrous composition and the other is non magnetic Each revolution of the spindle motor causes the ferrous tab to pass within close proximity of the Index sensor therefore inducing the pulse output Note The dimension between the spindle motor tab and the Index sensor is set to 30 mils 030 at the factory 2 2 3 Ground Spring The ST 506 incorporates a grounding contact between the spindle motor hub and the drive casting This ground spring performs the task of removing all unwanted static electrical charges from the spindle motor hub Seagate Technology PAGE 7 5 1 82 Theory of Operations ST 506 Service Manual 2 2 4 Spindle Brake The ST 506 uses an electromechanical brake to slow the spindle motor when DC power is removed The spindle brake is energized directly from the 12V supply When 12V is removed from the drive the brake engages against the spud motor hub to slow the motor The pad contact areal
26. eek Complete active 5 Write Gate active With write gate active and all the above conditions true 12V is supplied to the write circuit current source which provides a constant 25ma 50 ma peak to peak When active Reduced Write Current will pull approximately 2ma out of the current source This reduces the peak to peak write current to approximately 46ma MEM write data is received by the line receiver and clocks the D type flip flop The driver transistors alternate write current between the windings of the selected head The center tap of the selected head is at ground potential when Write Gate is active When Write Gate goes false the D type flip flop is both reset and preset Both driver transistors are biased off and 12V is removed from the write circuit Seagate Technology _ PAGE 19 5 1 82 Theory of Oper ations ST 506 Service Manual 2 3 7 Fault Detection Block Diagram DRIVE SELECT SEEK COMP Functional D escription Any combination of the following events will cause a Write Fault condition and will prevent the drive from writing 1 Multiple heads selected 2 DC voltages more than 20 low 3 Write Gate active and no write current 4 Write Gate inactive and write current 5 Seek Complete inactive 6 Drive Select inactive 7 Ready inactive The Head Unsafe circuit monitors the head select output for the following conditions i No head selected 2 Multiple heads selected 3
27. f 5 C51 31 1 CAP ELECIRCLYTIC 22uf 16V C27 32 7 CAP TANT 4 7uf 35V 10 C14 15 22 25 2 33 2 CAP CERAMIC 150pf NPO 5 C17 24 34 1 CAP CERAMIC 068uf X7R 10 C21 35 1 CAP CERAMIC 100pf NPO 5 C8 36 1 CAP CERAMIC 330pf NPO 5 10 37 1 CERAMIC 470pf NPO 5 C20 38 31 CAP CERAMIC 10 250 80 20 C1 3 5 6 11 13 18 19 26 30 35 37 41 43 50 39 1 PCLYCARB luf 50V 10 C23 40 1 DICDE ZENER 2 4 2 1N5221 31 41 13 DICDE 1N4148 CR11 12 15 17 42 4 DICDE 1N4003 CR19 22 43 1 DICDE ZENER 4 3V 5 1N5229B R18 44 1 CAP TANT l 0uf 35V 10 C43 Seagate Technology 50 5 1 82 Illustrated Parts Catalog x 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 66 67 68 69 70 71 AW UI mM Ww BR N SI A I N j W RA RI PO 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 Ei N ho a OV m WW HS N s OU Seagate Technology scriptio INDUCTCR 2 2uh INDUCTOR 10uh 3 3 DICDE UNITRODE NDP767 TRANSISTCR 2N3904 I C NE592 LOW NOISE RESISTOR 1 8W 1 RESISTOR 1 8W 1 RESISTOR 1 8W 1 RESISTOR 1 8W 1 RESISTOR 1 8W 1 RESISTOR 1 8W 1 RESISTOR 1 8W 1 RESISTOR 1 8W 1 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4W 5 RESISTOR 1 4
28. g enough for C5 to charge to more than 4 volts and force pin 1 of Comparator A2 low This low pulse will turn on pin 7 of Al whose resulting 6 volt output pulse will direct pin 7 of Integrator A2 to allow more current to enter the motor coils The sequence of normal operation is as follows 1 The Hall effect sensor relays speed and position information to the speed error comparator and to the current controller 2 The speed error comparator pin 1 of A2 generates a low spike whose duration is dependent on the speed error A slow speed will result in the low pulse being longer Seagate Technology PAGE 9 5 1 82 Theory of Operations ST 506 Service Manual 3 The speed error information enters the starting circuit which functions to pass a low frequency signal directly to the integrator indicating maximum error during start up The starting circuit also inverts the speed error information and combines it with a carrier that properly biases the integrator 4 Pin 7 of Integrator A2 translates the error information into a level appropriate for biasing both halves of IC A1 which functions to control the current source 5 The current control supplies the proper amount of current for attaining proper speed as directed by IC Al Seagate Technology PAGE 10 5 1 82 Theory of TRACK f PHASE A Operations ST 506 Service Manual 2 3 2 Auto Recalibration Block Diagram 512 PULSE CANTER Functional D escri
29. heads when operational are supported on an air bearing created by the rotating disc The Winchester heads used are loaded toward the disc surface at 9 5 grams This is the typical value to allow required stability in all operating conditions The flying height of the heads at the innermost cylinder is 19 microinches with a tolerance of 3 microinches The flying height of the heads at the outermost cylinder is 24 microinches 3 micrcinches The load force of 9 5 grams is sufficient enough so that various mounting orientations of the disc drive will not affect the flying height of the Winchester heads to any significant degree Additionally the head flexture assembly incorporates an extremely low mass design that is resistive to head and or media damage when shipping 2 1 4 Discs The ST 506 disc drive uses two non removable double sided 5 1 4 inch discs as the recording media The discs are designed upon current iron oxide technology The actual disc dimensions are 40mm inside diameter by 130mm outside diameter Thickness of the magnetic coating is 20 to 40 microinches increasing linearly from the inside diameter to the outside diameter The disc surface is coated with a Teflon lubricant 40 to 60 angstroms in thickness This value is equivalent to a uniform monomolecular film The disc lubricant has sufficient abrasion resistance to withstand a minimum of 10 000 start stop cycles The magnetic discs have a life expectancy of 5 years
30. ions must be true 1 Write Gate inactive 2 Write Fault inactive 3 Direction In if Track g is true 4 Drive Ready 5 Step pulse on the interface When a step pulse is applied to the drive interface the step circuitry will immediately process it The pulse is changed to 1 0 microsecond in width by the monostable multivibrator and is then gated through to the up down counter The counter will count up if the Direction line is low and will count down if the Direction line is high An increasing count will cause the PROM to select motor phases that move the heads toward Track g The outputs from the PROM are active low which turn off the pre driver transistors The inactive state of any pre driver transistor causes a current flow through the Darlington drivers To ensure fast head settling the stepper motor is always locked between two phases For this reason the stepper circuitry must receive two steps for each single track increment Subsequent to receiving an interface step pulse an internal step pulse is output by the second step generator This second pulse is injected 2 8 milliseconds after the first This time interval is the optimum value to take advantage of the motor momeritum and obtain the quickest settling time Seagate Technology PAGE 14 5 1 82 Theory of Operations ST 506 Service Manual Approximately 15 milliseconds after the last internal step pulse the retriggerable monostable multivibrator will time out a
31. nance R epair ST 506 Service Manual 3 2 9 Side Tools Required 5 64 Hex Driver 1 2 3 4 5 6 7 Loctite 242 Remove 4 6 32 x 1 4 Main Control P B mounting srews Disconnect P1 through P8 noting their positions Slide the Main Control P C B toward the rear of the dv and remove Remove 2 6 32 x 1 8 front cover mounting screws It is not necessary to remove the LED connector Remove 4 6 32 x 5 16 side frame mounting screws washers grommets and spacers Remove the right and left side frames To reinstall reverse the above procedure using Loctite on the first three threads of all 6 32 screws Seagate Technology PAGE 39 5 1 82 Illustrated Parts Catalog ST 506 Service Manual 4 0 ILLUSTRATED PARTS CATALOG 4 1 Physical Locations 4 1 1 Drive Exploded View 4 1 2 Connectors Exploded View Seagate Technology PAGE 40 5 1 82 LV AVVG i M o M OTHERWISE NOTED Linear 22 XXX ANGULAR Heels OUTSIDE BROKEN TINSIDE 2 TOLERANCE UNLESS D ree eec MAE Mie MINE Fee DIP SHUNT 7 POS N PWB ASSY CONTROL PABASSY MTRONTL 20003000 ASSY SPINDLE BRAKE WASHER FLAT 6 SPACER SHOCK MNT 58023 156 ds SHOCK MOUNT 52025000 B GROMMET PANEL 13025 001 L E D 1850 003 m COVER FRONT gt E FRAME RIGHT SIDE 5 FRAME LEFT SIDE MG ASSY INDEX amp LED CONN
32. nd generate the Seek Complete signal Note that during the stepping routine the multivibrator is constantly triggered which maintains an inactive signal on the Seek Complete line Seagate Technology PAGE 15 5 1 82 ST 506 Service Manual TABLE 2 1 Theory of Operations 1 delel dellla eledel dz s bl b EH dbz od cd ee A el 1 1 1 115121 1 a wawaman CD AM e sa s r T w m ss s G s w r s u s EE s SE s Se IC 2C Step pulse encoding IC 2D Phase sequencing 5 1 82 PAGE 16 Seagate Technology Theory of Operations ST 506 Service Manual Ex SELECT 2 3 5 Read Operation Block Diagram meae pu eem DETECTOR j Functional D escription In order to read the following conditions must be true 1 Write Gate inactive 2 Write Fault inactive 3 Drive Select active 4 Head Select active The binary decoder decodes the two Head Select lines the Write Gate line and the Write Fault line Assuming Write Gate is inactive and there is no write fault the inactive state of both head select lines will select head g The center tap of the selected head is set to approximately 5 volts by the use of series resistors By changing the reference to 5 volts 0 volts appears as 5 volts and the use of an actual negative voltage is precluded Raw data riding on the 5 volt signal is amplified by the differential two stage amplifier before entering the low pas
33. ndication est Point d ens Test Point 4 may be used to monitor the Index sensor A high logic level is a valid Index indication Only the leading edge of the pulse may be considered valid The typical signal at Test Point 4 should resemble Figure 3 3 Test Point 4 may be used to adjust the spindle motor speed Monitor Test Point 4 and adjust R3 on the Motor Control P C B accessible through the side frame for a period of 16 67 milliseconds 1 t i ompl imer Test Point 5 may be used to monitor the Seek Complete timer The timer should go true approximately 18 milliseconds after the last interface step pulse is received To observe the Seek Complete timer trigger on Test Point 1 and monitor the delay at Test Point 5 Only the trailing edge of the pulses may be considered valid The typical signal at Test Point 5 should resemble Figure 3 4 Seagate Technology PAGE 22 5 1 82 Theory of Operations ST 506 Service Manual est Poin ck WA Test Point 6 may be used to check the operation of the Track Zero Phase A circuitry A high logic level indicates the drive is at Track Zero with the stepper motor phase A active Test Points 7 and 8 Differential Read Filter Test Points 7 and 8 may be used to observe the differential read data The typical amplitude of the signal resulting from adding the two channels is 250 millivolts It is important that Test Points 9 and i0 are used as ground Components of 1 25 1 66 and 2 5
34. of 3 The ST 506 specification for spindle speed variation is 1 over the specified environmental and power limits Seagate Technology PAGE 4 5 1 82 8 39Vd FIGURE 20 TRACK FORMAT AS SHIPPED ua oe A Repeated 32 times 314 Bytes Gap 1 ID Field j Gap 2 Data Field Gap 3 Gap 4 SYNC C 57 8 61 1 HART 16X4E 13XOOIA1 FE L D C C C 3x00 13x00 256 Data c 3x00 4 v Nominal ID AM Data AM WRITE UPDATE NOTES 1 Nominal Track Capacity 10416 Bytes Total Data Bytes Track 256 x 32 8 192 Sector interleave factor is 4 Sequential ID Fields are sector numbered 8 16 24 1 9 17 25 2 10 18 26 etc A Data Fields contain the bit pattern 0000 as shipped CRC Fire Code 8 12 5 1 Bit 7 of Head Byte ID Field equals 1 in a defective sector Cylinder is error free Bit 5 of Head Byte reserved for numbering cylinders greater than 256 SSE SE AE Bit 6 of Head Byte reserved for numbering cylinders greater than 512 Theory of Operations ST 506 Service Manual 2 1 3 Winchester Heads The Seagate Technology ST 506 uses conventional Winchester head technology The head flexture supporting arm assembly is designed for contact start stop operation Bit packing density is 7690 BPI and the radial track density is 255 TPL The
35. ools Required 5 64 He pave Loctite 242 1 Remove 4 6 32 x Er Main Control P C B mounting srews 2 Disconnect P1 through P8 noting their positions 3 Slide the Main Control P C B toward the rear of the drive and remove 24 To reinstall reverse the above using lective on the first three threads of all 6 32 screws Note Avoid flexing the Printed Circuit Cable when removing P5 29 7 lt a lt a lt leh YA Ro Tools Required 5 64 Hex Driver Loctite 242 1 Remove 4 6 32 x 1 4 Main Control mounting screws 22 Disconnect P1 through P8 noting their positions 3 Slide the Main Control P C B toward the rear of the drive and remove 4 Disconnect Motor Control 1 and P2 noting their orientation 5 Remove 2 6 32 x 1 4 Motor Control mounting stews 6 Remove the Motor Control P C B 7 To reinstall reverse the above procedure using Loctite on the first three threads of all 6 32 screws Note Whenever the Motor Control is replaced or if any of its components are changed the spindle speed must be adjusted Connect a frequency counter to Test Point 4 Index and adjust R3 the Motor Control P C B accessible through the sideframe for a period of 16 67 milliseconds The frequency counter must average 100 samples per minute minimum Additonally if C5 is replaced the Motor Control P C B must be burne
36. ovided by the controller to insure data integrity at the specified error rate The ST 506 requires precompensation of write data on cylinders 128 through 152 The data pattern determines which bits must be precompensated The recommended amount of this precompensation is 12ns for both early and late written bits All other data patterns are written on time 2 1 2 Track Format The track format used on the 5 506 disc drive is slightly modified version of the IBM System 34 double density format This format is common to many industry standard floppy disc drives All ST 506 drives are formatted at the factory before shipping Data fields contain the bit pattern 0000 Refer to Figure 2 1 Track Format The Seagate sector format divides each esek into 32 sectors with each containing 256 bytes of data Total track capacity is 10416 bytes of which 8192 bytes are data Each sector is identified by an identification field that is different than any other on the drive The ID field contains cylinder head and sector information as well as address mark and error checking polynomials It should be noted that the format used by Seagate is recommended and not required Use of any other format requires careful evaluation as the format is an integral part of the drives performance and operation The Seagate format uses Cyclic Redundancy Checking CRC for error evaluation The format also allows for a plus or minus speed variation
37. ption Upon initial power application the up to speed counter up to speed latch and recalibration latch are all reset Before the drive can perform any read write or seek operations it must first become Ready At power on Ready is a combination of the drive being up to speed and an active Track f As the drive begins to spin an index pulse from the Index sensor is supplied to the index counter once each revolution When the index counter reaches 512 the drive is assumed to be rotating at its full speed of 3600 revolutions per minute The output from the up to speed counter clocks the up to speed latch Since the recalibration latch was reset at power on it will force the direction of the stepper motor outward If the heads are not positioned over Track each successive index pulse will increment the up down counter For each increment of the counter the phase encoder will select a stepper phase that moves the heads one half of a track closer to Track g If the heads are behind Track f they will move to Track f immediately since at power on the up down counter will be reset to Phase A When the heads reach Track g the recalibration latch will be clocked high In its high condition the recalibration latch will release the Direction line and block any future index pulses from being gated through as a step pulse The recalibration latch in conjunction with the up to speed latch will provide the Ready signal to the drive interf
38. r 1 2 3 4 5 6 7 8 9 Loctite 242 30 Mil Shim 030 Remove 4 6 32 x 1 4 Main Control P C B mounting srews Disconnect P1 through P8 noting their positions Slide the Main Control P C B toward the rear of the drive and remove Remove the connector from the front panel LED noting the orientation of the connector Free the index sensor wires from the retaining clip Remove 2 6 32 x 1 8 index sensor mounting screws and mounting clamp Remove the index sensor To reinstall apply Loctite to the first three threads of the index sensor mounting screws Replace the index sensor mounting clamp and mounting screws but do not tighten Rotate the spindle motor housing until the silver index tab aligns with the index sensor Seagate Technology PAGE 36 5 1 82 Maintenance R epair i ST 506 Service Manual 10 Using the 30 mil shim adjust the gap between the index sensor and the index tab 11 Tighten the 2 mounting clamp screws and verify that the gap is 30 mils 12 Route the index sensor wires through the retaining clip ane reconnect the LED 13 Reverse steps 1 through 3 to replace the Main Control B using loctite on the first three threads of all 6 32 screws Tools Required 5 64 Hex Driver P Loctite 242 1 Remove 4 6 32 x 1 4 Main Control P C B mounting srews 2 Disconnect P1 through P8 noting their positions 13 Slide the Main Control P C B the rear of
39. s filter which attenuates the higher unused frequencies The differentiator shifts the data by 909 causing the data peaks to become zero crossings The zero crossing detector senses this and converts the analog input to TTL levels The time domain filter inhibits any false zero crossings that may be found on the outer edge of the disc surface These false crossings are primarily caused by excessive third harmonics in the analog signal Seagate Technology PAGE 17 5 1 82 Theory of Operations ST 506 Service Manual The differential receiver and 2 input Exclusive OR gate form a bidirectional monostable multivibrator The output of this device is delayed 60ns by the four Hex Schmitt triggers This delay is used to clock the output of the zero cross detector into the D type flip flop Any false clocks caused by a false zero crossing does not change the state of the flip flop The last differential receiver and 2 input Exclusive OR gate form bidirectional monostable multivibrator that establishes the width of the data pulse output from the drive The line driver converts the data pulse to differential RS 422 levels a 2742 Seagate Technology PAGE 18 5 1 82 Theory of Operations ST 506 Service Manual LINE RECEIVER 2 3 6 Write Operation Block Diagram Functional D escription In order to write the following conditions must be true 1 Write Fault inactive 2 Drive Select active 3 Drive Ready active 4 S
40. t this adjustment be performed at the factory 3 2 7 Eront Cover Tools Required 5 64 Hex Driver Loctite 242 1 Remove 4 6 32 x 1 4 Main Control mounting srews 2 Disconnect Pi through P8 noting their positions 3 Slide the Main Control toward the rear of the drive and remove 4 Remove the connector from the front panel LED noting the orientation of the connector 5 Remove 2 6 32 x 1 8 front panel mounting screws 6 Remove the LED and grommet from the front panel noting the orientation of the LED 7 Remove the front panel 8 To reinstall reverse the above procedure using Loctite on the first three threads of all 6 32 screws z Note A water base hot meli glue may be used to secure the LED grommet assembly 3 ron Tools Required 5 64 Hex Driver Loctite 242 1 Remove 4 6 32 x 1 4 Main Control P C B mounting srews 2 Disconnect P1 through P8 noting their positions 3 Slide the Main Control P C B toward the rear of the drive and remove 4 Remove the connector from the front panel LED noting the orientation of the connector Black wire to single dot 5 Remove the LED and grommet from the front panel noting the orientation of the LED 6 To reinstall reverse the above procedure using Loctite on the first three threads of all 6 32 screws Note A water base hot melt glue may be used to secure the LED grommet assembly Seagate Technology PAGE 38 5 1 82 Mainte
41. the drive and remove 4 Remove 1 6 32 x ae ground spring mounting screw and spacer 25 Remove the ground spring 6 reinstall apply Loctite to the first 3 threads of the ground spring mounting screw Replace the ground spring spacer and mounting screw 7 Center the ground spring over the spindle motor contact ball and tighten 8 Verify that the ground spring button and spindle motor ball are clean and making good contact 9 Reverse steps 1 through 3 to replace Control P c using Loctite on the first 3 threads of all 6 32 screws 3 2 6 Track d Sensor Tools Required 5 64 Hex Driver tot 050 Hex Driver Loctite 242 1 Remove 4 6 32 x 1 4 Main Control P C B mounting srews 22 Disconnect P1 through P8 noting their positions 23 Slide the Main Control toward the rear of the drive and remove 4 Remove 2 6 32 x 1 8 front panel mounting screws 5 Remove the front panel It is not necessary to remove the LED connector 6 Remove 2 2 56 x 1 8 track f sensor mounting bracket retaining screws 7 Remove the mounting bracket and track f sensor noting the orientation of the track f sensor 8 To reinstall reverse the above procedure using Loctite on the first 3 threads of all screws Seag ate Technology 37 5 1 82 Maintenance R epair ST 506 Service Manual Note Proper positioning of the Track sensor is important It is recommended tha
42. ystem Low cost and unit reliability are achieved through the use of a band actuator and open loop stepper head positioning mechanism The inherent simplicity of mechanical construction and electronic controls allows maintenance free operation throughout the life of the drive Both electronic PCB s are mounted outside the HDA for field serviceability Mechanical and contamination protection for the heads actuator and discs are provided by an impact resistant aluminum enclosure A self contained recirculating system supplies clean air through a 0 3 micron filter second port in the filter assembly allows pressure equalization with ambient air without chance of contamination A patented spindle pump assures adequate air flow and uniform temperature distribution throughout the head and disc area Thermal isolation of the stepper and spindle motor assemblies from the disc enclosure yields a very low temperature rise within the enclosure providing significantly greater off track margin and the ability to immediately perform read and write operations after power up with thermal stabilization delay The ST 506 electrical interface is similar to the Shugart Associates SA1000 family of 8 inch fixed disc drives The ST 506 size and mounting are identical to the industry standard minifloppy disc drives and uses the same DC voltage and connector No AC power is required Seagate Technology PAGE 1 5 1 82 Introduction 1 2 Specification Summary
Download Pdf Manuals
Related Search