Radio Shack Mini Disk Service Manual
Contents
1. Radio Shaek Service anual T HS 80 MINI DISK Catalog Number 26 1160 1161 L CUSTOM MANUFACTURED IN U S A FOR RADIO sHack MA DIVISION OF TANDY CORPORATION TABLE OF CONTENTS PAGE INTRODUCTION ASSY 171013 001 1 Power Sup rias e pied P sA 1 SECTION I GENERAL DESCRIPTION Loup 566043 Ea Ga o IR EA 3 INTRODUCTION otsa 0 asf mnl 3 Physical Descripllon di Rn RR abra 3 Functions air SA Gas 3 Connections lt lt veis xiv ona Sw ares Ve irs qa era 3 Phyile Checkout as ness row yv RYE mes 3 Mount gm DK DUM oda ees mA Stn mw hito wpsus os KE kya koq 5 Resistor Termination DIP Shunt and Jumper 5 Flat Ribtion Galle ANTI icici vasca xe we stein rm uim n a erm 5 SECTION il THEORY OF OPERATION Mr e rr sie EG WIRE ORT CE Rt 7 Orgsnizstion of the Disk Drive 525 occ ccc s ss s cece clases 7 Functional Block Diagram Description s s asa nnn 7 NONE Sa Zal zo OSO GRA 7 WTS PYOEOEE a Sa 7 Trek SES aa a S IS a Gia BE EIE eee 7 SUNG LICE Z GS CASO VUE W 7 6 0 0 0 A 7 Inn EM Masta anay ciii s E B Dus REGNA oo ec GA WEGA Vip s CR wie tit 9 Reno ET ET ETT ELT O 8 SECTION HI OPERATION rid PG worka DY KW AWS 11 Interface Elec2. CABLE ASSEMBLY CONNECTOR PIN REMOVAL CHART Page Intentionally Left Blank SECTION Il THEORY OF OPERATION INTRODUCTION The Disk Drive consists of the mechanical and electrical components necessary to record and read digital data on a diskette DC power at 12 V and 5 V provided by the user is required for operation ORGANIZATION OF THE DISK DRIVE All electrical subassemblies in the Disk Drive are constructed with leads which terminate in 4 or 5 pin connectors ena bling the individual assemblies to be removed The magnetic head is connected to the PC board via a cable terminating in a 5 pin female connector and its associated male socket which is located in close proximity to the read write data electronics Interface signals and power are provided via connectors at the rear of the Drive A detailed description of these signals is presented in Section III of this manual FUNCTIONAL BLOCK DIAGRAM DESCRIPTION Figure 5 is a functional block diagram of the Disk Drive and should be referred to in conjunction with the following discussion The Disk Drive consists of the following functional groups Index Pulse Shaper Write Protect Sensor Track 00 Sensor Spindle Drive Control Carriage Position Control Write Erase Control Read Amplifier and Digitizer INDEX An index pulse is provided to the user system via the INDEX PULSE interface line The index circuitry consists of an Index LED Index Phototransisto
3. the bit serial WRITE DATA pulses that control the switch ing of the write current in the head The write electronics must be conditioned for writing by the WRITE ENABLE line refer to the WRITE ENABLE paragraph below For each high to low transition on the WRITE DATA line a flux change is produced at the head write gap This causes a flux change to be stored on the disk When the double frequency type encoding technique is used in which data and clock form the combined Write Data signal it is recommended that when writing all zeroes the repetition rate of the high to low transitions be equal to the nominal data rate 0 136 The repetition rate of the high to low transitions when writing all ones should be equal to twice the nominal data rate 0 196 WRITE ENABLE NWRITE GATE When this signal is true low the write electronics are pre pared for writing data read electronics disabled This signal turns on write current in the read write head Data is written under control of the WRITE DATA input line It is generally recommended that changes of state on the WRITE ENABLE line occur before the first WRITE DATA pulse However the separation between the leading edge of WRITE ENABLE and the first significant WRITE DATA pulse should not be less than 4 and not greater than 8 The same restrictions exist for the relationship be tween the least significant WRITE DATA pulse and the 11 Controller to Disk Dri
4. EY we 26 SECTION V INTRODUCTION MINI 25060 27 Resistor Termination DIP Shunt and Jumper 27 eret 27 LIST OF ILLUSTRATIONS FIGURE PAGE 1 Mini Disk Power Supply Schematic 1 2 PC Board Component 5 4 3 Resistor Termination DIP Shunt and Jumper 5 4 Cable Assembly Connector Pin Removal Chart 5 5 Functional Block Diagram ac oo hr mmn 8 6 X a 8 7 WIE OTS SORE HY 10 8 naad AMIS DOGG we v sa s v fait s mr 10 9 11 10 Circuit Board Test Points and Connector Locations 16 11 CN Seve PRIMI presul ea wta hr ER PRAE FRE 18 12 KAGERO DEM uiua aeo Boo PIRE CR Saa 18 13 Servo Motor Control Board Schematic 19 14 Mini Disk Drive Schematic Sheet 1 20 14 Mini Disk Drive Schematic Sheet 2 21 SECTION V 15 Resistor Termination DIP Shunt and Jumper 27 16 Cable Assembly Connector Pin Removal Chart 27 TABLE 1 Mini Disk Drive Mechanical and Electrical Specifications 2 2 Interface Connector Pin Assignments J1 P1 12 3 Power Connector Pin Assignment 12 MINI DISK SERVICE MANUAL ASSY 71013 001 INTRODUCTION This manual provides a General Des
5. Gate These lines are terminated through a 150 ohm resistor pack installed in a DIP socket located at IC location 2F In a single drive system Catalog Number 26 1T60 this resistor pack should be kept in place to provide the proper terminations In a multiple drive system Catalog Numbers 26 1160 and one to three 26 1161 s only the last drive on the interface is to be terminated All other drives on the interface must have the resistor pack removed Catalog Number 26 1160 is shipped with the termination resistor installed Catalog Number 26 1161 is shipped without a resistor pack 15 HEAD J3 READ WRITE HEAD CONNECTOR O O 9 TERMINATOR SOCKET 2F TPi2 9 s STEPPER der MOTOR w SERVO JUMPER me e T9123 x YW RE M 054 12 CONNECTION po 00000 0000 0000 44 POWER CONNECTOR NUSED 5 m 9 UNU w w I O INTERFACE za 9 x CONNECTION G J1 INTERFACE CONNECTION s 35 c z LOGIC BOARD COMPONENT SIDE SERVO JUMPER DRIVE MOTOR R4 SPINDLE SPEED CONTROL SERVO BOARD COMPONENT SIDE FIGURE 10 CIRCUIT BOARD TEST POINTS AND CONNECTOR LOCATIONS 16 PREVENTIVE MAINTENANCE To ensure that the Disk Drive operates at its design poten tial the only scheduled preventive maintenance required is periodic cleaning of the magnetic recording head Mechanical and electrical adjustment details are provided for further service as a
6. PART NUMBER 7000008 7000007 7000008 8790104 8569046 8569032 8589025 SECTION V MINI DISK SERVICE MANUAL MINI 25060 xx INTRODUCTION This manual provides service information for the Mini Disk Power Supply Termination Resistor Package DIP Shunt Jumper Wire and Cable Connectors for Serial Numbers MIN125060 xx Resistor Termination DIP Shunt and Jumper refer to Figure 15 1 The Resistor Termination in the IC socket is used in Drive number zero only It must be removed for Drives one two and three 3 JUMPER WIRE ADDED TO ALL DRIVES FOOU 1 RESISTOR TERMINATION IN SOCKET REMOVE EX CEPT FOR DRIVE NUMBER ZERO Service information for this system can be found in the SA400 Minifloppy Diskette Storage Drive Service Manual published by Shugart Associates dated March 1977 The Shugart Manual follows these pages 2 The DIP Shunt package is used in all Drives and must be punched and seated as illustrated 3 The Jumper Wire between pins 10 and 32 of J1 is used on all Drives ET 2 DIP SHUNT PACKAGE 12 PIN DIP SITS IN UP PER PART OF 14 PIN DIP SOCKET MUST BE PUNCH ED AS SHOWN IN ALL DRIVES FIGURE 15 RESISTOR TERMINATION DIP SHUNT AND JUMPER Flat Ribbon Cable Assembly see Figure 16 Pins must be removed from Drive connectors on the Cable Assembly as follows and as illustrated 1 Connector for Drive number zero pins 12 14 and 32 2 Conn
7. Time Head Settling Time Error Rate Head Life Media Life Disk Speed Instantaneous Speed Variation Start Stop Time Transfer Rate Bits Disk unformatted Recording Modes typical Power Industry compatible 5 1 4 inch 133 4 mm diskette 4B 35 9 912 inches 252 mm 3 38 inches 85 85 mm 5 87 inches 149 10 mm 8 0 inches 203 2 mm 4 5 Ibs 2 04 Kg 10 C to 43 C 50 F to 110 F 40 C to 71 C 40 F to 160 F 20 to 80 5 to 95 non condensing 6 to 600 Hz 0 5g oeak 5 msec track to track 15 msec last track addressed 1 per 109 recoverable 1 per 1012 non recoverable 20 000 hours normal use 3 million passes on a single track 300 rpm 1 5 long term 3 0 250 msec maximum 125 250K bits sec 1 75 million FM FM MFM MMFM 12 V dc 0 6 V 900 ma maximum 5 V dc 0 25 V 600 ma maximum TABLE 1 MINI DISK DRIVE MECHANICAL AND ELECTRICAL SPECIFICATIONS SECTION I GENERAL DESCRIPTION INTRODUCTION The Disk Drive is a MINI Disk Memory designed for ran dom access data entry storage and retrieval applications These applications typically are intelligent terminal control lers micro computers word processing systems data com munications systems error logging micro program loading and point of sale terminals The Disk Drive is capable of re cording and reading digital data using FM MFM or M2FM techniques PHYSICAL DESCRIPTION The electronic components are mou
8. WRITE DATA pulse Note that a minimum of 4 uSec and a maximum of 8 Sec between WRITE ENABLE going true and the first WRITE DATA pulse is only required if faithful reproduction of the first WRITE DATA transition is significant At the end of recording at least one additional pulse on the WRITE DATA line must be inserted after the last significant WRITE DATA pulse to avoid excessive peak shift effects The TRIM ERASE signal must remain true for BOO uSec after the termination of WRITE ENABLE to ensure that all recorded data are trim erased This value is again optimized between the requirements at Tracks 00 and 34 The duration of a write operation is from the true going edge of WRITE ENABLE to the false going edge of TRIM ERASE This is indicated by the internal WRITE BUSY waveform shown DATA REPRODUCTION The Read Electronics consists of the following Read Switch Read Amplifier Filter Differentiator Comparator and Digitizer The Read Switch is used to isolate the Read Amplifier from electrical signals across the magnetic head during a write operation Before reading can begin the Drive must be in a ready con dition As with the data recording operation this ready condition must be established by the user system In addi tion to the requirements established in the paragraph DATA RECORDING a 100 uSec delay must exist from the trailing edge of the TRIM ERASE signal to allow the Read Amplifier to settle after th
9. at the top rear of the module 2 Follow the instructions that came with the CE Diskette 3 Manually rotate the cam at the rear of the module until the cat s eye pattern shown in Figure 11 is Observed Carefully rotate the cam until the cat s eye pattern has equal amplitudes 4 Secure the module by tightening the three retaining screws that were previously loosened 5 After securing the module screw verify Step 4 Repeat s required INDEX SENSOR ALIGNMENT 1 Position the Index sensor to the center of travel lightly tighten the retaining screw 2 Perform the CE alignment as required to locate the cat s eye pattern referto RADIAL TRACK ALIGN MENT above 3 Perform fifteen step out commands to position the carriage to Track 01 4 Set the oscilloscope horizontal time base to 50 uSec per division 5 Referring to Figure 12 adjust the photo transistor mounting block until the first transition of the 2 mSec burst recorded at Track 01 occurs 200 50 uSec after the leading edge of the index pulse Ad justment may be made with the use of a flat bladed screwdriver placed between the photo transistor mounting block and the Cone Lever as required 6 Secure the retaining screws on the photo transistor mounting blocks and verify the burst location Read just as necessary TRACK 06 SWITCH 1 Apply the necessary power and control to turn on the Drive 2 Insert the CE Alignment Diskette into the Drive and close
10. result of disassembly or repair CLEANING THE HEAD To clean the magnetic head use a lint free cloth or cotton swab moistened with 91 Isopropy alcohol Wipe the head carefully to remove all accumulated oxide and dirt Dry the head using a lint free cloth CAUTION Rough or abrasive cloth should not be used to clean the magnetic recording head Use of cleaning solvents other than 9196 Isopropy alcohol may damage the head Extreme care must be exercised to prevent the heads from being damaged i e scratching banging together etc ADJUSTMENT CE ALIGNMENT The CE alignment procedure locates the magnetic read write head at the proper radial distance from the hub centerline thus assuring accurate track location This adjustment is necessary only after service or for suspected diskette inter change problems DISK DRIVE PREPARATION 1 Apply the necessary power and control to turn on the Disk Drive 2 Insert a CE Alignment Diskette Dysan Part Number 224 2A or equivalent into the drive and close the front latch 3 Attach oscilloscope probes to test points TP1 and TP2 Place the ground clip of the signal probes to TP10 Adjust the oscilloscope to read differentially A B with B inverted Sync the oscilloscope on the leading edge of the Index pulse at TP7 with the sync probe ground clip at TP6 RADIAL TRACK ALIGNMENT 1 Loosen do not remove the two module retaining screws on the bottom of the chassis and the one
11. the Drive and an appropriate signal is applied to the interface When performing a write opera tion a 0 013 inch 0 33 mm nominal data track is re corded When performing a write operation a 0 013 inch 0 33 mm nominal data track is recorded Data recovery electronics include a low level read amplifier differentiator zero crossing detector and digitizing circuits No data decoding facilities are provided in the basic Drive The Drive is also supplied with the following sensor systems 1 A track 00 switch which senses when the Head Carriage assembly is positioned at Track 00 2 The index sensor an LED light source and a photo transistor is positioned so that when an index hole is detected a digital signal is guaranteed The index sensor used is a high resolution device which can distinguish holes placed close together i e in dex sector holes in a hard sectored diskette 3 The write protect sensor disables the Disk Drive electronics whenever a write protect tab is applied to the diskette INTERFACE CONNECTIONS Signal connections for the Disk Drive are made via a user supplied 34 pin flat ribbon connector 3M Part Number 3463 001 or equivalent This connector mates directly with the PC board connector J1 at the rear of the Drive The DC power connector is a four pin connector J2 which is keyed to mate with the connector on the Logic PC board at the top rear of the Drive The signal connector harness sh
12. the front latch 3 Position the carriage to the radial alignment track Confirm the position by observing the cat s eye pattern 17 4 If adjustment is required remove the CE Diskette Loosen the retaining screw on the base of the Track 00 bracket retighten slightly to provide some fric tion on the bracket and rotate the Track 00 Adjust ment Screw at the rear of the chassis counter clockwise as far as it will go without forcing it 5 Position the carriage to Track Q1 by performing repetitive step out pulses 6 Rotate the Track 00 Adjustment Screw clockwise very slowly until the switch clicks Then rotate the screw clockwise same direction exactly one half turn 7 Tighten the retaining screw previously loosened WRITE PROTECT SWITCHES 1 Insert a non write protected diskette partially half way into the Drive 2 Ensure that the switch is actuated 3 Insert the diskette fully against the diskette back stop and close the front latch Ensure that the switch is deactivated 4 Adjust the switch by loosening the retaining screw removing the switch assembly and setting the switch higher or lower as required DRIVE MOTOR SPEED 1 Appiy the necessary power and control to turn on the Drive 2 Insert the Diskette 3 Ensure that the Drive Motor Enable line is active 4 Adjust the Speed Control potentiometer on the Servo board until the timing disk is stationary in fluorescent lig
13. 1 Q2 INTEGRATED CIRCUITS LM2917N Frequency to Voltage Converter 8050917 DISK DRIVE PARTS AND SUBASSEMBLIES PART DESCRIPTION NUMBER SYMBOL Drive Motor Assembly 8852015 Track 00 Switch Assembly 8852016 Write Protect Switch Assembly 8552017 Belt Drive 8852018 Index Assembly 8552019 LED Assembly Panel 8552020 Cone Assembly 8552021 Latch Assembly 8552022 Right Hand Guide 8552023 Left Hand Guide 8552024 Front Panel 8552025 Front Panel Bushing 8552026 Upper Bearing 8552027 Lower Bearing 8552028 Module Assembly SSR 8552029 Stepper Motor Assembly 8552030 Head Carriage Assembly SSR 8552031 Drive Band Stepper 8552032 Included in Module Assembly SSR DESCRIPTION RESISTORS 20 K 1 4 W 5 1 M 1 4 W 5 1 K 1 4 W 5 1 K Trim Potentiometer 1 K 1 4 W 5 43 2 K 1 4 W 1 470 ohms 1 4 W 596 470 ohms 1 4 W 596 18 ohms 1 4 W 5 1 K 1 4 W 5 1 ohm 1 2 W 596 2 2 K 1 4 W 5 2 2K 1 4 W 5 TRANSISTORS TIP110 Power 2N4124 NPN MISCELLANEOUS 10 pin Right Angle Header 4 40 x 1 4 Screw Pan Head 4 40 Hex Nut DRIVE ASSEMBLY PARTS LIST DESCRIPTION Drive Assembly Disk Controller Board Assembly Servo Board Assembly Disk Drive 6 32 x 1 2 Screw Phillips 2 4 40 x 1 4 Screw 2 6 Spacer Nylon 2 PART NUMBER 8207320 8207510 8207210 8289210 8207210 8201343 8207147 8207147 8207018 8207210 8217001 8217222 8207222 8110110 8110124 8519057 8569032 8579001
14. 4 25 7406 Buffer and Interface Gate 8010406 C19 0 01 uF 50V 8383104 3g 74LS20 Positive NAND Gate 8020020 C20 0 01 uF 50V 8383104 4g 74LS20 Positive NAND Gate 8020020 C21 0 01 uF 50V 8383104 5g MLM 311EL Precision Comparator _ 8050311 C22 0 01 uF 50V 8383104 20 75463 Dual Peripheral Positive OR C23 0 01 uF 50V 8383104 Driver 8050463 C24 Not Used 3C 74LS123 Retriggerable Monostable C25 0 01 uF 50V 8383104 Multivibrator 8020123 C26 6 8 uF 35V 8335683 4C 74LS74 Flip Flop 8020074 C27 0 01 uF 50V 8383104 sc 74LS74 Flip Flop 8020074 C28 0 01 uF 50V 8383104 3p 74LS04 Positive NAND Gate 8020004 029 0 01 uF 50V 8383104 4p 75462 Dual Peripheral Positive C30 6 8 uF 35V 8335683 NAND Driver 8050462 C31 0 01 uF 50V 8383104 gp 741 586 Quadruple 2 input Exclusive C32 0 01 uF 50V 8383104 OR Gate 8020086 C33 0 01 uF 50V 8383104 1g DIP Shunt 16 pin 8489001 C34 0 01 uF 50V 8383104 2g 74LS14 Schmitt Trigger Positive C35 0 01 uF 50V 8383104 NAND Gate 8020014 C36 4 7 uF 20V 8315472 z 7407 Buffer and Interface Gate 8010407 C37 4 7 uF 20V 8315472 75462 Dual Peripheral Positive C38 6 8 uF 35V 8335683 NAND Driver 8050462 C39 6 8 uF 35V 8335683 74LS221 Dual Monostable Multi C40 330 pF 50V 8381334 vibrator w Schmitt Trigger Inputs 8020221 C41 330 pF 50V 8381334 4f 74LS38 Buffer and Interface Gate 8020038 2F B resistor Network 8290007 DIODES 4F 74LS38 Buffer and Interface Gate 8020038 CR1 1N4446 Switching 8150446 If applic
15. ED CIRCUIT PLUGS zi Voltage Regulator Socket Connector 8159008 Plug Power 4 ea 8159006 NOTE The 34 contact Feedthrough Connector Part Number 8519004 is not listed or shown as part of the Power Supply However it interconnects the Power Supply and the Mini Disk Drive P C B PART NUMBER 8100601 8247833 8207210 8207156 8207222 8207233 8207215 8278210 8489020 8790012 8050723 DISK CONTROLLER BOARD PARTS LIST PART PART SYMBOL DESCRIPTION NUMBER SYMBOL DESCRIPTION NUMBER PRINTED CIRCUIT BOARD CR11 1N4446 Switching 8150446 DISK CONTROLLER 8709094 CR12 1N4446 Switching 8150446 CR13 1N4446 Switching 8150446 CAPACITORS CR14 1N4446 Switching 8150446 CR15 1N4446 Switching 8150446 C1 2 2 uF 35V 8395223 CR16 1N4446 Switching 8150446 C2 470 pF 50V 8381474 CR17 1N4446 Switching 8150446 C3 68 pF 50V 8381684 CR18 1N4446 Switching 8150446 C4 0 47 uF 50V 8384474 CR19 1N4446 Switching 8150446 C5 0 47 uF 50V 8384474 CR20 1N4446 Switching 8150446 C6 0 01 50V 8383104 CR21 1N4446 Switching 8150446 67 0 47 uF 50V 8384474 C8 0 47 uF 50V 8384474 INDUCTORS C9 4700 pF 50V 8382474 C10 0 01 uF 50V 8383104 1 390 uh 8419003 C11 270 pF 50V 8381274 12 390 uh 8419003 C12 470 pF 50V 8381474 13 680 uh 8419004 C13 470 pF 50V 8381474 C14 1200 pF 50V 8382124 INTEGRATED CIRCUITS C15 0 1 uF 20V 8394102 C16 0 1 uF 20V 8394102 34 MC 1733 8050733 C17 4 7 uF 20V 8315472 44 NE 592A 8050592 C18 0 01 uF 50V 838310
16. IC Socket 2 R29 22 1 4 W 5 8207222 16 pin DIP Shunt Socket R30 2 2 K 1 4 W 5 8207222 5 pin Right Angle Header R31 768 ohms 1 4 W 1 8201176 14 pin Right Angle Header 2 R32 820 ohms 1 4 W 5 8207182 Staking Pin 13 R33 390 ohms 1 4 W 5 8207139 Resistor value Jumper 2 R34 1 54 K 1 4W 1 8201215 4 position PC Mount Housing R35 768 ohms 1 4 W 1 8201176 R36 Not Used If Applicable R41 Not Used R42 1 K 1 4 w 5 8207210 R43 1 K 1 4 W 5 8207210 R44 3 K 1 4 W 5 8207230 R45 10 K 1 4 W 5 8207310 R46 Not Used R47 1K 1 4 W 5 8207210 R48 300 ohms 1 4 W 5 8207130 R49 1K 1 4 W 5 8207210 R50 Not Used R51 Not Used R52 150 ohms 1 4 W 5 8207115 R53 1 K 1 4 W 5 8207210 R54 13 3 K 1 4 W 1 8201313 PART NUMBER 8201328 8247115 8207210 8207210 8207210 8207115 8207310 8207210 8207175 8207139 8207210 8207210 8110124 8110124 8110124 8110124 8100125 8110124 8489001 8519054 8519060 8529014 8290000 8519056 SYMBOL C1 C2 C3 C4 C5 c6 CR1 L1 U1 SYMBOL SERVO MOTOR CONTROL BOARD PARTS LIST PART DESCRIPTION NUMBER SYMBOL PRINTED CIRCUIT BOARD SERVO MOTOR CONTROL 8709096 R1 CAPACITORS R2 R3 1uF 35 V 8335103 R4 1uF 35 V 8335103 R5 1uF 35 V 8335103 R6 1uF 35 V 8335103 R7 0 047 uF 80 V 8393474 R8 0 47 uF 35 V 8394473 R9 R10 DIODES R11 R12 1N4002 Rectifier Low Power 8150002 R13 INDUCTORS 3 3 uh 10 8419005 Q
17. RESISTOR TERMINATION DIP SHUNT AND JUMPER See Figure 3 1 The Resistor Termination in the IC socket is used in Drive number zero only It must be removed for Drives one two and three 1 RESISTOR TERMINATION UN SOCKET REMOVE EX CEPT FOR DRIVE NUMBER ZERO 2 DIP SHUNT PACKAGE 16 PIN DIP MUST BE PUNCHED AS SHOWN iN ALL DRIVES IF APPLICABLE 2 The DIP Shunt package is used in all Drives and must be punched and seated as illustrated NOTE Some Logic PC boards will not have a DIP Shunt in the Drive Select circuit These boards have been redesigned and the Drive Select circuit is etched into the board 3 The Jumper Wire between pin 32 of J1 and the DS4 connection see Figure 5 is used on all Drives NOTE Some Logic PC boards will not have the Jumper Wire The connection will be etched into the board FIGURE 3 RESISTOR TERMINATION DIP SHUNT AND JUNPER FLAT RIBBON CABLE ASSEMBLY see Figure 4 Pins must be removed from Drive connectors on the Cable Assembly as follows and as illustrated 1 Connector for Drive number zero pins 12 14 and 32 2 Connector for Drive number one pins 10 14 and 32 DRIVE DRIVE NUMBER ZERO NUMBER ONE 3 Connector for Drive number two pins 10 12 and 32 4 Connector for Drive number three pins 10 12 and 14 Do not remove any pins from the connector to the Expan sion Interface DRIVE DRIVE NUMBER TWO NUMBER THREE FIGURE 4
18. able CR2 1N4446 Switching 8150446 CR3 1N4446 Switching 8150446 CR4 1N4446 Switching 8150446 CR5 Not Used CR10 Not Used 24 DISK CONTROLLER BOARD PARTS LIST Cont d PART SYMBOL DESCRIPTION NUMBER SYMBOL DESCRIPTION RESISTORS R55 28 7 K 1 4 W 1 R56 Not Used R1 8 2 K 1 4 W 5 8207282 R57 Not Used R2 8 2 K 1 4 W 5 8207282 R58 150 ohms 2 W 5 R3 8 2 K 1 4 W 596 8207282 R59 1 K 1 4 W 5 R4 27 K 1 4 W 5 8207327 R60 1 K 1 4 W 5 R5 27 K 1 4 W 5 8207327 R61 1K 1 4 W 5 R6 3 6 K 1 4 W 1 8207236 R62 150 ohms 1 4 W 5 R7 1 K 1 4 W 5 8207210 R63 10 K 1 4 W 5 R8 1K 1 4 W 5 8207210 R64 1 K 1 4 W 5 R9 1K 1 4 W 5 8207210 R65 750 ohms 1 4 W 5 R10 1K 1 4 W 5 8207210 R66 390 ohms 1 4 W 5 R11 1 K 1 4 w 5 8207210 R67 Not Used R12 1K 1 4 W 5 8207210 R68 1K 1 4 W 5 R13 1 2 K 1 4 W 5 8207212 R69 1 K 1 4 W 5 R14 150 ohms 1 4 W 5 8207115 R15 Not Used TRANSISTORS R16 1K 1 4 W 5 8207210 R17 1 K 1 4 W 5 8207210 Q1 2N4124 NPN R18 1 K 1 4 W 5 8207210 Q2 2N4124 NPN R19 1K 1 4 W 5 8207210 Q3 2N4124 NPN R20 750 ohms 1 4 W 5 8207175 Q4 2N4124 NPN R21 390 ohms 1 4 W 5 8207139 Q5 2N4125 PNP R22 10 K 1 4 W 5 8207310 Q6 Not Used R23 390 ohms 1 4 W 5 8207139 Q7 Not Used R24 3 09 K 1 4 W 1 8201230 Q8 2N4124 NPN R25 768 ohms 1 4 W 1 8201176 R26 3 9 K 1 4 W 5 8207239 MISCELLANEOUS R27 1K 1 4 W 5 8207210 R28 47 K 1 4 W 5 8207347 16 pin
19. cription of the Mini Disk Drive System It also includes Theory of Operation Operation Maintenance Schematics and Parts Lists for Drives that have Logic PC boards with the serial number ASSY 171013 001 Service information for Drives that have serial numbers such as MINI25060 xx can be found in the back of this manual following the Parts Lists The Power Supply Case and external Cables are the same for both units The Power Supply Specifications are slightly different POWER SUPPLY SPECIFICATIONS NEUE SR SS RATED M ZY Syses 120 VAC 60 Hz OUTPUT ca 12 0 6 VDC CURRENT 4 ara UZ wis Paya ara 900 mA max 0 75 A typ MAXIMUM RIPPLE QUTPUT er area CURRENT Xy 29 09 55 whee Ten ik MAXIMUM RIPPLE NOTE Refer to Section V Output 1 current is rated at 1 50 A max This value occurs only during Head Loading and lasts approximately 200 ms 120 VAC 60 HZ NOTES UNLESS OTHERWISE SPECIFIED 1 ALL RESISTORS ARE 1 4 WATT 5 RESISTOR VALUES IN OHMS K 1000 2 CAPACITOR VALUES IN MICROFARADS AND WORKING VOLTAGE 3 7 INDICATES CLOCKWISE ROTATION 12 V RE TURN MCI723CP TOP VIEW FIGURE 1 MINI DISK POWER SUPPLY SCHEMATIC Media Tracks per inch Number of Tracks Read Write Track Width Dimensions Exclusive of Media Operating Non operating Relative Humidity Exclusive of Media Operating Non operating Vibration Seek
20. d Trim Erase Control Logic The read write winding on the magnetic head is center tapped During a write operation current from the Write Current Source flows in alternate halves of the winding under control of the Write Waveform Generator Before recording can begin certain conditions must be satisfied The conditions required for recording i e unit ready must be established by the user system as follows 1 Drive speed stabilization This condition will exist 250 mSec after starting the drive motor 2 Subsequent to any step operation the positioner must be allowed to settle This requires 20 mSec total after the last step pulse is initiated i e 5 mSec for the step motion and 15 mSec for settling NOTE All of the foregoing operations can be overlapped if required Figure 7 shows the relevant timing diagram for a write oper ation At t when the unit is ready the WRITE ENABLE interface line goes true this enables the Write Current Source Since the trim erase gaps are behind the read write gap the TRIM ERASE control goes true 390 uSec after the WRITE ENABLE interface line It should be noted that this value is optimized between the requirements at Track 00 and Track 34 so that the effect of the trim erase gaps on pre vious information is minimized Figure 7 also shows the information on the WRITE DATA interface line and the output of the Write Waveform Gen erator which toggles on the leading edge of every
21. e transient caused by the Read Switch returning to the Read mode Referring to Figure 8 the output signal from the read write head is amplified by a read amplifier and filtered to remove noise by a linear phase Filter The linear output from the Filter is passed to the Differentiator which generates a waveform whose zero crossovers correspond to the peaks of of the read signal This signal is then fed to the Comparator and Digitizer circuit The Comparator and Digitizer circuitry generates a 1 uSec READ DATA pulse corresponding to each peak of the read signal This Composite Read Data signal is then sent to the user system via the READ DATA interface line WRITE NAME TERNAL were BUSY l i 1 GtwEnaron wara CURRENT note 1 0 FRO MALLOECONDS AFTER DRIVE MOTOR 2 UW TWOWNOWIIED STARTS OF 20 MILLISECONDS AFTER LAST STEP Gna Pasa TOC PULSE WHICHEVER 5 THE LATEST Tu 4 SECONDS MINIMA Q SECONDS MA MOM FIGURE 7 WRITE TIMING DIAGRAM 4 NOTE 1 LINEAR OUTPUT FROM FILTER OUTPUT FROM DIFFERENTIATOR READ DATA INTERFACE 0 NOTES t 0 250 MILLISECONDS AFTER DRIVE MOTOR STARTS OR 20 MILLISECONDS AFTER STEP COMMAND OR 100 u SECONDS AFTER TERMINATION OF WRITE BUSY WHICHEVER IS THE LATEST TIME FIGURE 8 READ TIMING DIAGRAM 10 SECTION III OPERATION INTRODUCTION This section contains the interface description and the elec trical adjust
22. ector for Drive number one pins 10 14 and 32 3 Connector for Drive number two pins 10 12 and 32 4 Connector for Drive number three pins 10 12 and 14 Do not remove any pins from the connector to the Expansion Interface DRIVE NUMBER TWO FIGURE 16 CABLE ASSEMBLY CONNECTOR PIN REMOVAL CHART RADIO SHACK M DIVISION OF TANDY CORPORATION U S A FORT WORTH TEXAS 76102 CANADA BARRIE ONTARIO L4M 4W5 TANDY CORPORATION AUSTRALIA BELGIUM UK 280 316 VICTORIA ROAD PARC INDUSTRIEL D NANINNE BILSTON ROAD WEDNESBURY RYDALMERE NSW 2116 5140 NANINNE WEST MIDLANDS WS10 PRINTED IN U S A
23. hting 94 d TIME SCALE T FIGURE 11 CAT S EYE PATTERN TIME SCALE 40 useri DIV FIGURE 12 18 INDEX TO DATA P20 J1 12V GND N MOTOR ON FIGURE 13 SERVO MOTOR CONTROL BOARD SCHEMATIC 19 L 3984S 2ILVIWW3HOS JAYA OISICHINIIN tL 381914 wa 219945 JILVIN3HOS JAIHG ASIG INIW 380913 21 Page Intentionally Left Blank SYMBOL 8989882 CR1 CR2 CR3 CR5 CR6 CR7 CR8 CR10 P1 MINI DISK POWER SUPPLY PARTS LIST PART DESCRIPTION NUMBER SYMBOL DESCRIPTION PRINTED CIRCUIT BOARD TRANSISTORS POWER SUPPLY 8790008 Q1 I C Voltage Regulator 7805 CAPACITORS Q2 MJE3055 Power 2 200 uF 25V Electrolytic Radial 8328222 RESISTORS 2 200 35V Electrolytic Radial 8328223 0 001 uF 100V Polyester Film 8352105 R1 0 33 ohm 2W 5 220 uF 16V Electrolytic Radial 8327221 R2 10K 1 4W 5 220 uF 16V Electrolytic Radial 8327221 R3 560 ohms 1 4W 596 220 uF 35V Electrolytic Radial 8327223 R4 2 2K 1 4W 5 R5 3 300 ohms 1 4W 5 DIODES R6 1 500 ohms 1 4W 596 R7 1K 30 Variable 1N5392 100V Silicon 8150392 1N5392 100V Silicon 8150392 SWITCH 1N5392 100V Silicon 8150392 1N5392 100V Silicon 8150392 S1 DPDT 1N4002 100V Silicon 8150002 1N4002 100V Silicon 8150002 TRANSFORMER 1N5392 100V Silicon 8150392 1N5392 100V Silicon 8150392 T1 117 60Hz 1N5392 100V Silicon 8150392 1N5392 100V Silicon 8150392 INTEGRAT
24. il the head is moved away from Track 00 WRITE PROTECT NWRITEPROTECT When the Disk Drive is selected this signal line logic level goes true low when the diskette is write protected The write electronics are internally disabled when the diskette is write protected NOTE It is recommended that the write data line be in active whenever Write Enable is false i e read state When the level on this line is false high the write electron ics are enabled and the write operation can be performed It is recommended that the controller not issue a write com mand when the WRITE PROTECT signal is true low READ DATA NREADDATA This interface line transmits the readback data to the con troller when the Drive is selected It provides a pulse for each flux transition recorded on the medium The READ DATA output line goes true low for a duration of 1 uSec for each flux change recorded The leading edge of the READ DATA output pulse repre sents the true positions for the flux transitions on the disk ette surface 13 Page Intentionally Left Blank SECTION IV MAINTENANCE PHYSICAL DESCRIPTION OF THE PC BOARDS The Logic PC board is approximately 6 inches 152 mm long by 5 5 inches 139 mm wide Figure 10 illustrates the placement of test points and connectors CIRCUIT BOARD TEST POINTS The following test point description assumes that the Logic and Servo P C boards are installed in the Drive and that the Drive
25. is in an operational mode with a diskette installed Logic Ground TP6 Digital Logic ground is referenced at TP6 Differentiated Read Signal TP3 TP4 These test points are provided to observe the differ ential output of the second stage amplifier and differ entiated read signal Read Data Single Shot TP5 The output of the single shot used in the read section is nominally 1 0 usec for each flux transition detected Index Pulse TP7 With a standard soft sectored diskette installed the signal is a high going pulse nominally 4 0 msec in dura ation every 200 msec Amplified Read Signal TP1 TP2 These test points are provided to observe the differ ential output of the first stage of read signal amplifi cation Motor On TP13 This signal is low true for the motor on condition Track 66 TP8 This signal is low true when the carriage is positioned at track 00 and the step motor phase is correct Analog Ground TP10 The analog ground reference point is provided for measuring read write waveforms Step Pulse TP12 When stepping in or out the signal is a high going pulse for each step of the carriage Write Protect Switch TP9 When a write protected diskette is installed in the Drive the signal is high OPTION SELECT Input Line Terminations The Disk Drive has been provided with the capability of terminating the input lines listed below Motor On Direction Select Step Write Data Write
26. ments necessary for the Disk Drive INTERFACE ELECTRONICS SPECIFICATIONS All interface signals are TTL compatible Logic true low is 0 4 V maximum Logic false high is 2 4 V minimum Figure 9 illustrates the interface configuration TRANSMISSION LNE su aw mecie I t ev i FIGURE 9 INTERFACE CONFIGURATION It is recommended that the interface cable be a flat ribbon cable with a characteristic impedance of 100 ohms or equivalent twisted pairs Maximum interface cable length is 10 feet 3 M Interface connector pin assignments and power connector pin assignments are given in Table 2 and Table 3 INPUT CONTROL LINES see Table 2 SELECT LINES NDS1 NDS4 The SELECT lines provide a means of selecting and deselec ting a Disk Drive These four lines NDS1 NDS3 are stan dard NDS4 is optional select one of the four Disk Drives attached to the controller When the signal logic level is true low the Disk Drive electronics are activated and the Drive is conditioned to respond to step or read write com mands When the logic level is false high the input control lines and output status lines are disabled A SELECT line must remain stable in the true low state until the execution of a step or read write command is completed The Disk Drive address is determined by SELECT lines 1 through 4 or a DIP Shunt in the 1E position on the PC board These lines provide a means of dais
27. n the current through the drive motor exceeds 1 3 A the current limit circuitry disables the motor drive POSITIONER CONTROL The Head Positioning system utilizes a four phase stepper motor drive which changes one phase for each track ad vancement of the Read Write carriage In addition to the logic necessary for motion control a gate is provided as an element for inhibiting positioner motion during a write operation SINGLE KOED LAD 8L v STAPPER wOTOR READ AMPLIFIER AND DIGITIZER FIGURE 5 FUNCTIONAL BLOCK DIAGRAM DATA ELECTRONICS Information can be recorded on the diskette using a double frequency code Figure 6 illustrates the magnetization pro files in each bit cell for the number sequence shown The erase gaps provide an erased guard band on either side of the recorded track This accommodates the tolerances in track positioning rc wt CELL Mit PATTERN i y 4 w wTEDATA All signals required to control the data electronics are pro vided by the user system and are shown in the Block Dia gram Figure 5 These control signals are SELECT WRITE ENABLE WRITE DATA The READ DATA composite signal is sent to the user system via the interface FIGURE 6 F M RECORDING DATA RECORDING Referring to Figure 5 it can be seen that the Write Elect ronics consists of a Write Erase Current Source and Write Waveform Generator Erase Current Source an
28. nted on two PC boards the Logic board located above the chassis and the Servo board mounted at the rear of the Unit Power and Interface signals are connected directly to the Logic board Figure 2 The spindle is belt driven by a DC motor with an integral tachometer The servo control circuit pulleys and the tachometer control the speed of the spindle The read write erase head assembly is positioned by means of a stepper motor split band and a pulley FUNCTIONAL DESCRIPTION The Disk Drive is fully self contained It consists of a spindle drive system a head positioning system and read write erase system When the front latch is opened access is provided for the insertion of a 5 25 inch 133 4 mm standard diskette The diskette is positioned in place by plastic guides the front latch and a back stop Closing the front latch activates the cone clamp system which centers and clamps the diskette to the drive hub The drive hub is driven at a constant speed of 300 rpm by a servo controlled DC motor In operation the magnetic head is loaded into contact with the recording medium whenever the front latch is closed A 4 phase stepper motor band assembly and its associated electronics position the magnetic head over the desired track This positioner employs a one step rotation to cause a 1 track linear movement When a write protected diskette is inserted into the Drive the write protect sensor disables the write electronics of
29. ould be of the flat ribbon or twisted pair type with the following characteristics 1 Maximum length of 10 feet 3 M 2 22 24 gauge conductor compatible with the con nector to be used Power connections should be made with 18 AWG cable minimum PHYSICAL CHECKOUT Before applying power to the unit the following inspection should be performed 1 Front latch Check that the front latch opens and closes Note that when the door is opened the head arm raises 2 Ensure that the front panel is secure 3 Manually rotate the drive hub The hub should rotate freely 4 Check that the PC boards are secure Check that the connectors are firmly seated 5 Check for debris or foreign material between the heads and remove same NOTE To ensure proper operation of the Drive the chassis should be connected to earth ground The 3 16 inch 4 76 mm male QC lug located at the rear of the chassis is provided for this connection 2 c4 KM cR20 Ra47 LOGIC BOARD COMPONENT SIDE J1 SERVO JUMPER DRIVE MOTOR A4 SPINDLE i aa id SERVO BOARD COMPONENT SIDE FIGURE 2 PC BOARD COMPONENT LOCATIONS MOUNTING THE DISK DRIVE The Drive can be mounted in any plane i e upright hori zontal or vertical However when it is mounted horizon tally the Logic PC board side of the chassis must be the uppermost side Tapped holes are provided in various loca tions for the attachment of user supplied hardware
30. r and a Pulse Shaping Network As the index hole in the disk passes the Index LED Phototransistor combination light from the LED strikes the Index Phototransistor causing it to conduct The signal from the Index Phototransistor is passed to the Pulse Shaping Network which produces a pulse for each hole de tected This pulse is presented to the user on the INDEX PULSE interface line WRITE PROTECT A Write Protect signal is provided to the user system via the WRITE PROTECT interface line The write protect circuitry consists of a Write Protect Sensor and circuitry to route the signal produced When a write protected diskette is inserted in the drive the sensor is activated and the logic disables the write elect ronics and supplies the status signal to the Interface TRACK 660 SWITCH The level on the TRACK 00 interface line is a function of the position of the magnetic head assembly When the head is positioned at Track 00 and the stepper motor is at the home position a true level is generated and sent to the user SPINDLE DRIVE The Spindle Drive system consists of a spindle assembly driven by a DC motor tachometer combination through a drive belt Associated with the spindle drive motor are the servo elec tronics required for control The control circuitry also includes a current limiter and an interface control line When the DRIVE MOTOR ENABLE interface line is true the drive motor is allowed to come up to speed Whe
31. tronics Specifications 11 innut Gontial LINE 5 s ackienale Yom eia naa 11 Select Ee NOSE NDS Uus u lt w wawa rain eruta GR KAS ae Seen 11 Drive Motor Enable 11 Direction and Step Lines 2 Lines DIR 5 11 Write Data NWRITEDATA EI RUOTA SS 11 Weite Enchie ONWRITE GATED 5 su Cu a disraera 11 Ouipat BENE oec E R va x aa BG GA 4 13 A peg Gio vm vow mo pnmo cw je 13 Tescili LL oue x 13 Wis PIONCCINWRITEPRUISECT QS ena oim PG wien a ew RR 4 13 INREADORATA 44 isco Ka GG mn na IIR pa MER 13 TABLE OF CONTENTS Cont d PAGE SECTION IV MAINTENANCE Physical Description of the PC Boards 15 Cid PORTE TRMEPANE 15 Ont BOE ursi ati ws RSE WSW pata PA ater Qu ESO 15 PUSO OR MalatenWidl os va vor 30 55 ce ETEN ew KT ZE 17 OGR 6 5a Usa 17 ADJUSTMENT CE ANNE AM RAK 17 Disk Drive Papat MIA 46 as capa 14 mah Fata A GK a kz A 17 Pell TER ows ua 17 MAG OGG 2 054 dix 17 TOK OE GRE AMETE Pe 17 La PC zaw RT POT Ni Blan 18 Dre NOE SDM WEZ ai ore e WW MIA Z 18 PARTS LIST PAIRED Pour SDDDIV cus Veo Va Wierd i GAZ ores 23 BONO vo vitto SS wale sla pla WSW Xa Ee 24 Servo Motor Control Board ois cis y ao br S
32. ve Ground i Description Mnemonic Connector clamp Spare Spare SELECT 1 NDS1 SELECT 2 NDS2 SELECT 3 NDS3 DRIVE MOTOR ENABLE NMOTORON DIRECTION STEP NSTEP WRITE DATA NWRITEDATA WRITE GATE NWRITEGATE SELECT 4 NDS4 Description Mnemonic INDEX NINDEX SECTOR TRACK 00 WRITE PROTECT NWRITEPROTECT READ DATA NREADDATA Connector Clamp TABLE 2 INTERFACE CONNECTOR PIN ASSIGNMENTS J1 P1 12 V DC Return 12 V DC Return 5 V DC 5 VDC TABLE 3 POWER CONNECTOR PIN ASSIGNMENT 12 termination of the WRITE ENABLE signal When the WRITE ENABLE line is false high all write electronics are disabled When a write protected diskette is installed in a Disk Drive the write electronics are disabled irrespective of the state of the WRITE ENABLE line OUTPUT STATUS see Table 2 INDEX NINDEX SECTOR The INDEX signal is provided once each revolution 200 mSec nominal to indicate to the controller the beginning of a track The INDEX line remains in the true low state for the duration of the INDEX pulse The duration of an INDEX pulse is nominally 4 0 mSec The leading edge of an INDEX pulse must always be used to ensure diskette interchangeability between Disk Drives TRACK 60 NTRK00 When the Disk Drive is selected the TRACK 00 interface signal indicates to the controller that the read write head is positioned at Track 00 The Track 00 remains true low unt
33. y chaining a maximum of four Disk Drives to a controller Only one line can be true low at a time An undefined operation might result if two or more units are assigned the same address or if two or more SELECT lines are in the true low state simultaneously DRIVE MOTOR ENABLE NMOTORON When this signal line logic level goes true low the drive motor accelerates to its nominal speed of 300 rpm and stab ilizes in less than 250 mSec When the logic level goes false high the Disk Drive decelerates to a stop DIRECTION and STEP Lines 2 Lines DIR NSTEP When the Disk Drive is selected a true low pulse with a time duration greater than 200 nSec on the STEP line initi ates the access motion The direction of motion is deter mined by the logic state of the DIRECTION line when a STEP pulse is issued The motion is towards the center of the disk if the DIRECTION line is in the true low state when a STEP pulse is issued The direction of motion is away from the center of the disk if the DIRECTION line is in the false high state when a STEP pulse is issued To ensure proper positioning the DIRECTION line should be stable 0 1 uSec minimum before the trailing edge of the corresponding STEP pulse and remain stable until 0 1 uSec after the trailing edge of the STEP pulse The access motion is initiated on the trailing edge of the STEP pulse WRITE DATA NWRITEDATA When the Disk Drive is selected this interface line provides
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