About the Maintenance Guide
Contents
1.2. About the Author Mr Peltier has nine years professional yo experience in electronics technical x writing and circuit and software design Among his works are i TIT ea WQ w A UR Far 5 wie TS reme eh E 91541 Single Drive Floppy Disk Maintenance Manual e1541 Programmers Reference Card e1541 Heat Dissipating Kit eDAS 1541 Head Alignment Kit for 1540 1541 About the Maintenance Guide By public request the author has compiled this maintenance guide This guide contains the following excerpts from the 1541 Single Drive
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4. 2 3 Preparation for calibration Detailed disassembly assembly instructions can be found in the 1541 Maintenance Manual 1 Remove top cover 2 Remove RFI shield 3 Disconnect p from 4 Reinstall RFI shield 5 Remove bottom cover 6 Place disk drive on left hand side Use a thin book or magazine to prop up drive Refer to Figure 2 1 Page 2 1 ACCESS HOLE FOR VR1 TIMING DISK 2 4 D e sir p d dapi ver k W IN sr eu 6 reme 60 Hz TIMING MARKS M Figure 2 1 VIC 1541 Prepared for Calibration Calibration 1 Connect VIC 20 COMMODORE 64 to video monitor or TV Refer to computer User s Guide for proper connection 2 Connect serial bus cable between PA on VIC 1541 and serial bus connector on VIC 20 COMMODORE 64 3 Connect AC power cord between J9 on VIC 1541 and outlet USE EXTREME CARE TO AVOID CONTACT WITH FRAME COMPONENTS HIGH AC VOLTAGE POTENTIALS ARE PRESENT DURING CALIBRATION THESE VOLTAGE POTENTIALS CAN CAUSE BODILY INJURY OR DEATH 4 Place VIC 1541 power switch to ON AN 5 Apply power to VIC 20 COMMODORE 64 a 6 If a VIC 20 is the computer being used enter the following command OPEN 15 8 15 UI CLOSE 15 lt Return gt 7 Insert blank floppy disk into VIC 1541 8 Plug timing strobe light into AC outlet Position light near timing disk Refer to Figure 2 1 9 Enter following command into VIC 20 COMMO
5. If the VIC 20 is the computer in use enter the following command OPEN 15 B 15 Ue CLOSE 15 lt return gt 4 Load the Display T amp S program into the computer This program may be loaded from the Test Demo disk or it may be manually entered from the keyboard The Display T amp S program is listed in Appendix of the VIC 1541 Single Drive Floppy Disk User s Manual 5 Place a factory recorded floppy disk into the VIC 1541 6 Enter RUN lt return gt into the computer 7 When the Display T amp S program asks for a Track and Sector enter Track 1 Sector 1 8 After the head settles and the Display T amp S program begins displaying Track information adjust the Track 1 Stop adjustment in the following manner See Figure 2 3 Loosen the adjustment lock down screw Place 006 inch feeler gauge between Stop potrusion on the stepping motor hub Carefully adjust the Stop until feeler gauge just touches the potrusion on the stepping motor hub and the Stop NOTE Do not disturb position of the stepping motor shaft Tighten the adjustment lock down screw 9 Place VIC 1541 and VIC 20 COMMODORE 64 power switches to OFF 10 Re ssemble the VIC 1541 Page 2 10 SECTION 3 TROUBLESHOOTING Section 3 TROUBLESHOOTING 3 1 General This section requires only Multimeter digital type 15 recommended and will isolate a problem down to the sub assembly level It is set up so that even an
6. Gian sx s Pe 031 sou wa z 031 i xor amp 037 MS TL jet i Ace 3408 p H PT Asg diwO M22 228 2 on 8132 Schematic Page 4 17 1541 Disk Controller Figure 4 18 sank Ta 61 V bed yo p 9 T 3 ASTA TYGI sqied HD74LS42P Y gt a Y C Y a Y a Y aa 5 UE6 CRI CR3 901229 03 365AA6 3 HMEIIGP 3 LIS LIG am Y am V am V am C de V m 64HIOSU HD7406P 830740 3C1T D7406 _ y i M74LSI4P HD7406P SUD IT E Rs ce gt uw l S G e APPENDIX Fabrication of Video Detector Materials Required One One One One set of meter leads capacitor resistor 1K 10 1 4 W diode 1N4148 or equivalent Equipment and Supplies Knife Soldering iron Wire cutters Needle nose pliers Heat shrink tubing 1 2 inch Heat shrink tubing 3 16 inch Solder 60 40 resin core Scale ruler Ohmmeter String or two wire ties Preparation 1 2 Cut meter leads shown below cut here NOTE Strip off insulation 3 16 from both sides of cut oL Prepare diode shown below FA done Page A 1 3 Prepare
7. 1 1 2 2 Prepare resistor as shown below ne FF one Page 1 3 Prepare lamp as shown below 11 16 1 4 Ss 4 Tin all leads on lamp cord resistor and neon lamp Assembly 1 Slide 1 inch lengths of 1 8 inch heat shrink tubing onto each of the prepared leads of the lamp cord Do not shrink the tubing at this time HEAT SHRINKABLE TUBING 1 8 2 Solder components as shown below Either lead of the line cord may be soldered to the resistor as long as the other lead is soldered to the neon lamp RESISTOR 22K FOR 115 47 FOR 220 NEON LAMP SOLDER HERE Page B 2 3 Slide both pieces of heat shrink tubing toward the base of the neon lamp and then shrink the tubing 4 Slide a 2 inch length of 3 16 inch heat shrink tubing over neon lamp Position the end of the heat shrink tubing 3 16 inch up from the base of the neon lamp and then shrink the tubing BEFORE PLUGGING IN TIMING LIGHT USE OHMMETER TO VERIFY RESISTANCE BETWEEN POINTS A AND B 15 INFINITY Page B 3
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9. 4 1 Interconnect Diagram Page 4 2 CASE 55 HALF SHIELD p p L A gt ia 1 a ae a p SEA Ct DISK CONTROLLER BOARD CQ 5 J1 FRAME ASSY DRIVE UNIT CASE ASSY BOTTOM HALF Figure 4 2 Sub Assembly Identification Page 4 3 Page 4 4 Blank ASSV LINN 3AIHQ l HOLOM 315 UJANG viva dY WILN3Y3 3510 3 Qv 38 83183AN02 4 S 11801 svig il viva Qv3u 80193130 LL va 35 4 lt A lt YOLVUVAMOS ONZ is 31 0438 4300930 19 38 S3H21IAS svig 193108d 31181 NAIB 721190 Functional Block Diagram I l 4334084 3LIMM J8VN3 INAS 3148 43003230 553500 sas viva HITIOHLNOD 5 Figure 4 3 Niv 3054183 1 AS eng winas en Y 135 42012 sna 7191836 Cap ne NA RE ESA Eh ee u HOLIMS Aumay 7au ASSY 3WY4J BO1V 1938 8313119358 el Air 3Nn 2v AG 8019109398 831311238 AS AS AS ASSY 9 d H31T1OHLNOO ASIA 4 5 92 092 952 ONY SWHO NI 55 MP T N3dO Nado NAJO qasoq o
10. 49 19 29 91 16 91 20 6 1 46 e oO in L dNI Id Sht 1 2 1541 Disk Controller Schematic 4 17 Figure Page 4 16 SvI8 svig 8 Y v3H 3 8 84 431 1231084 JUM DH S N 2 AS 9 1931058 3LIUM 9 N 9 N DIN 2 N AG bru 90v 9 1 ost 4105 Seu Sch NI 2199 16 198 lt lt 2755 CH Ag lvl 9 1 azon ox x 5962652 o CH 1 xol die 9 1 Birt diel 9 1 220n 9 lt t s lt 6 divi 9 2 of 2 Sht m fin 031 55399 80883 ao 031 821140 9d so Or 18 0 s vsz ive 9 1 vian MV340 lt 1 94 ATHE ezon B s ovsz f AN Sd a r lt 3 dal 1241 AS s 0s T 9 1 668 3lon 825 ox RSA asit 902 9 sx 16 Wa 9 1 Divn va 9 b 10 p 902 s Vd d gian g9A 2 4 M vd I Pp v v x i Al s 123135 NOVEL td NAS E zvd INAS 2149 6 12 n DNAS 8 4 22 9z2 J lt 4 32012 u3g0330 u300583 g N3 WAS 3148 330 NC 4 15 4 v 1552 ec 90v 9
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12. Floppy Disk Maintenance Manual eCalibration including head alignment eTroubleshooting Part for the novice eSchematics and Parts Layout reference data for those with experience For additional information including Theory of Operation Advanced Troubleshooting and more see the 1541 Single Drive Floppy Disk Maintenance Manual 198 pgs 118 illus Published by PELTIER INDUSTRIES INC 735 N Doris Wichita Kansas 67212
13. N lt 04 pr __leem 7 55 R6 R8 09 820 BO O 47pF 35V OUTE 5 6 SPEED CTLR n ae WA SONY 2463 C4 ud FIL RI GND R2 1 R5 C7 e TK 0 47pF 35V c8 0 063pF T ADJUST 4 I OU weder A __ R7 5 IOK 4148 1 DRIVE MOTOR SERVO W 93 HOVL S3 2 340 NO 23 A2 I3 vH ZI eM oly e IgA E Drive Servo Circuit Parts Layout Figure 4 13 Page 4 13 JI AC INPUT J9 AC LINE SI POWER lev Qi AC HI GND iev 22 AC LO ge Figure 4 14 Frame Assv Schematic For use with P C Bd 1540048 JI AC INPUT SI POWER J9 AC LINE OR lev l AC HI GND 4 fiev 02 AGLO l 02 Figure 4 15 Frame Assy Schematic For use with P C Bd 1540001 Page 4 14 Ji F1 Frame Assy Parts Layout Figure 4 16 Page 4 15 N3dO NddO 035079 AISOTD ta 0ED 622 820 OIWVH3O QALON 3SIMNSHIO SSaINN SWHO NI Q3SS38dX3 SI HONVISISIN TIY 2 8841 0 MP T 401 HWV SYOLSISAN TIY I 11 T 035072 01 ao 1 st N3dO 6 As POTUM an rostm wi 0450712 8 SS330 V SSHUQOV NATITOULNOI ASIQ JHL WVHDONd Z3 ANY I3 p 40 170 Suv Q3ISIT SHOLIOVdVO HSHHL TIY ONY 3NIT AS JHI NS3MI38 GHLOSNNOO SHOLIOVdVO SSVdAH SNIMOTTO4 HHL E butsnoy 1030u BuTddaqs COS lt sl voon asan C og
14. POWER PUSH PULL OR LIFT THE VICTIM TO SAFETY USING A WOODEN POLE A ROPE OR SOME OTHER DRY INSULATING MATERIAL FIRST_AID AS SOON AS VICTIM IS FREE OF CONTACT WITH SOURCE OF ELECTRICAL SHOCK MOVE VICTIM A SHORT DISTANCE AWAY FROM SHOCK HAZARD SEND FOR DOCTOR AND OR AMBULANCE KEEP VICTIM WARM QUIET AND FLAT ON HIS HER BACK IF BREATHING HAS STOPPED ADMINISTER ARTIFICIAL RESUSCITATION STOP ALL SERIOUS BLEEDING TABLE OF CONTENTS Title FRONT MATTER Title Page Copyright Page Warning Page Table of Contents l wn i d d Pd dg d P gd o Ff gd d o MN MMM ISU S NM tS ho 2 N A YU yn P l P gt N gt C NO 4 1 Section l INTRODUCTION General VIC 1541 vs 1541 Warnings Cautions and Notes Section 2 CALIBRATION General Equipment Required Preparation for Calibration Calibration Head Alignment General Equipment Required Preparation for Mechanical Alignment Head Alignment Mechanical Alignment of Track fl Stop General Preparation for Mechanical Alignment Mechanical Alignment Section 3 TROUBLESHOOTING General TROUBLESHOOTING PART 1 Section 4 SCHEMATICS AND PARTS LAYOUT General APPENDICES Appendix A Video Detector Fabrication Appendix B Timing Strobe Fabrication Page 1 Page PRE l N N IS 2 IS iN i N iN N ND l I l l l OO 1 U UI
15. resistor shown below ef F3 ne 4 Tin all leads on resistor diode and meter leads Assembly 1 Slide 1 1 2 inch length of 1 8 inch heat shrink tubing onto red meter lead as shown below Do not shrink the tubing at this time Heat shrinkable tubing 3 16 3 length of red meter lead 2 Solder diode resistor and remaining end of meter lead together as shown below Note proper polarity of diode Cathode marking Resistor Solder here Remaining end of red meter lead Page A 2 3 Slide heat shrink tubing over diode resistor leaving one lead of resistor exposed and then shrink the tubing 4 Solder capacitor and black meter leads as shown below Tie meter leads where shown Solder here Black meter lead Solder here Tle here 5 Slide a 2 inch lenqth of 1 2 inch heat shrink tubing over capacitor and then shrink the tubing USING OHMMETER VERIFY RESISTANCE BETWEEN POINTS A AND B IS INFINITY Page A 3 APPENDIX B APPENDIX Fabrication of Timing Light Materials Required One neon bulb One lamp with appropriate plug One resistor 22K 103 1 4 W for 115 VAC 47 10 1 4 W for 220 VAC Equipment and Supplies Knife Soldering iron Wire cutters Needle nose pliers Heat shrink tubing 1 8 inch Heat shrink tubing 3 16 inch Solder 60 40 resin core Scale ruler Ohmmeter Preparation 1 Prepare lamp cord as shown below 3 16 pes pee 3 16
16. A i Zus O 9 04 OO a wo lt gt wo E R45 DS I POWER ET nen CASE ASSY OGRE NO pos N C GND 2 ZA GN 1 Figure 4 7 Case Assv Schemat PWR LED PWR LED DS1 Figure 4 8 Case Assy Parts Layout Page 4 9 ebed arun ATIA OTJEWJUDS 6 7 sandra WRITE PROTECT LED WRITE PROTECT 45 DRIVE MOTOR 1 O E2 OFF ON I2 V O I2V GND BK gt GND DRIVE MOTOR SERYO CIRCUIT 2 Jg READ WRITE UI READ WRITE HEAD E6 M E5 TACH E4 TACH N C HEAD BIAS BIAS HEAD B 46 OPTICS e ee 5V N C ERROR LED 55 ERROR LED N C N C PROTECT ve N C SENSOR WRITE PROTECT EMITTER N C N C GND GND ont STEPPING MOTOR E A es ee R W HEAD 01 1 Parts Layout Drive Unit Figure 4 10 OY B2 e 9 e DRIVE MOTOR SERVO CIRCUIT Bottom Parts Layout r Drive Unit Figure 4 11 Page 4 11 ZT y bed 4QTNOATD OA3 S ZI p eunbr4 OTJEWSJDS l El 12V tL a iod Ea Tach CRI CR4 7 4148 RI IOK ES TACH CR IN4148 E2 0N OFF R3 R9 220 P 95 t 1 c5
17. DORE 64 OPEN 15 8 15 N0 CAL 01 CLOSE 15 Return Page 2 2 10 Adjust VR1 Refer to Figure 2 1 until timing disk appears to stop INOTE 60 Hz AC is being used calibrate with the outer set of timing marks on the timing disk If 50 Hz AC is being used calibrate with the inner set of timing marks on the timing disk If further time is required to adjust go back to Step 9 and re enter command given 11 After drive motor has stopped place VIC 1541 power switch to OFF 12 Remove serial bus cable and AC power cord Reassemble the VIC 1541 Page 2 3 2 5 Head Alignment 2 5 1 General This procedure aligns the read write head to the physical tracks on a floppy disk A truly accurate alignment requires the use of an alignment reference disk and a test program disk The procedure which follows allows the user to get by without such software However the degree of success achieved will depend on the accuracy of the disk which is used Consequently the alignment may cause compatibility problems when using software recorded on other drives or when using other drives to read disks recorded on a drive aligned with this procedure This problem mav be reduced bv selecting a pre recorded disk which has not been written to since it was recorded at the factory Although this procedure is not 100 accurate it will usuallv suffice for the home user For an accurate alignment of the drive unit one
18. Formatting a blank floppy disk New command 2 Soft error recovery The procedure that follows should only be used after carefully verifying that the rest of the VIC 1541 is properly operating Complete coverage of proper operation is given in Troubleshooting Part 2 in the 1541 Maintenance Manual 2 6 2 Preparation for Mechanical Alignment Detailed disassembly assembly instructions can be found in the 1541 Maintenance Manual 1 Remove all external cables from VIC 1541 2 Remove upper cover 3 Remove RFI Shield 4 Remove Disk Controller PC Board 5 Remove Drive Unit 6 Reconnect JI to Pl 2 to P J5 to P5 J6 to P6 27 to 7 such manner that access is still allowed to the Track 41 Stop adjustment See Figure 2 3 CAUTION DO NOT ALLOW PATHWORK ON DISK CONTROLLER PC BOARD TO CONTACT THE FRAME OR DRIVE UNIT ASSEMBLIES USE AN INSULATING RUBBER MAT IF NECESSARY TO INSULATE THE DISK CONTROLLER PC BOARD FROM THESE ASSEMBLIES 2 6 3 Mechanical Alignment 1 Connect serial bus cable between P3 and VIC 20 COMMODORE Page 2 8 TRACK 1 STOP Figure 2 3 Track fl Stop Adjustment Page 2 9 Z Connect AC line cord between J9 AC outlet DO NOT CONTACT THE FRAME ASSEMBLY OR WIRING THE VOLTAGE POTENTIALS PRESENT ON THESE PARTS COULD CAUSE SEVERE INJURY OR DEATH 3 Place VIC 1541 power switch to and place power switch on computer being used to ON NOTE
19. Step 13 Page 3 7 STEP PROCEDURE ILLUSTRATION Remove wires from 27 Connect 77 to P7 Remove negative lead of DMM from side of C52 Set DMM to Ohms x 10 or Ohms x 100 range Connect negative and positive leads of DMM to pins of Jffas indicated table below Verify resistances indicated on DMM are within limits given in Ohms Ohms lead Min 1 pins D 29 39 pin4 C 12 22 pin3 B 23 33 NOTE This resistance check of the read write head does not check its dynamic characteristics If in doubt about the condition of the read write head refer to Part 2 of Troubleshooting Are all resistances correct Fault lies in Drive Unit Replace Place power switch to OFF Proceed to Step 14 Page 3 8 STEP PROCEDURE ILLUSTRATION Connect J to PZ Perform Calibration procedure in Section 2 Is drive motor rotating at correct speed At this point the problem lies in the Disk Control ler PC Board or in the Drive Unit To determine which of the two sub assemblies is bad refer to Part 2 of Troubleshooting in the 1541 Maintenance Manual Part 2 requires an oscilloscope and some technical exper ience If you do not wish to attempt Part 2 try swapping the Disk Controller PC Board or the Drive Unit with a known good assembly and see if the problem is solved Also check assemblies for obvious s
20. T qASOTD N3dO 6 QASOTO 095012 8 ca 18 SSIATOY SSAVOOY HA TIOHLNOO 3511 JHL SPO TRO LED 8 0 9 2 LPO 659 6 SED 9 2 BED ZED OINVHSO an T O TED LTD QED 022 82 629 612 120 zzo BTI 90 Suv 041511 SHOLIDWdWD ASAHL TIY S AHL NIIMLIE QALJANNOD SHOLIOVdVO SSVdK8 DNIMOTIOA QALON 3SIMHAHLO SSa INI qassagadxa SI SONVLSISSH TIY CALON 85 NAS 19 n MOD Ww300230 43002N1 SHOLSISSH TIY SALON TOS Te v 1 9533 205704 H UMd LNANI la 18 10 90 sa AS QO0S 3148 L3 an aah od AG dT A 8 135 X20125 ane 135 99012 NI 4231988 UYM D SR 031 4 Ot YIVO UBS 435 9 725 6 4 1 US Y 135 6 O Wi 6 SNE WIH3S ws Sw i 1 44 9 Ni DYS 835 6 en i 2 NAY 835 KALT POLE d sec x2 435 3IGVNI INAS 3148 6 en en 5 WUS 4410 22 ka e Sa A Er Se MA n I 9 10 Mie ir 3 295 29 Vo ALLIGSTOM 26 ig 9 28 6 6 1 ON of l 5 Scnematic Disk Controller Figure 4
21. TIT PI E PUBLISHED PELTIER INDUSTRIES INC 735 N Doris Wichita Kansas 67212 Copyright 1984 by MICHAEL G PELTIER All rights reserved Printed in the United States of America No part of this publication may be reproduced stored in a retrieval system or transmitted in any Form or by any means electronic mechanical photocopying recording or otherwise without the prior permission of the publisher The information in this manual has been reviewed and is believed to be entirely correct No responsibility however is assumed for any personal or property damage incurred from the use of this manual The material in this manual is for information purposes only and is subject to change without notice Commodore Business Machines Inc and the author of this manual advise that any attempt to repair the VIC 1541 or the 1541 disk drives during the warranty period will void the factory warranty VIC 1541 VIC 20 and COMMODORE 64 are registered trademarks of Commodore Business Machines WARNING HIGH VOLTAGE EQUIPMENT THIS EQUIPMENT CONTAINS CERTAIN CIRCUITS AND OR COMPONENTS OF EXTREMELY HIGH VOLTAGE POTENTIALS CAPABLE OF CAUSING SERIOUS BODILY INJURY OR DEATH WHEN PERFORMING ANY OF THE PROCEDURES CONTAINED IN THIS MANUAL HEED ALL APPLICABLE SAFETY PRECAUTIONS RESCUE OF SHOCK VICTIMS DO NOT ATTEMPT TO PULL OR GRAB VICTIM IF POSSIBLE TURN OFF ELECTRICAL POWER IF YOU CANNOT TURN OFF ELECTRICAL
22. e Place power switch to OFF Fault lies in Disk Control ler PC Board Repair or replace Connect J5 to P5 Place power switch to ON Does drive motor turn while red LED is Place power switch to OFF Proceed to Step 11 Place power switch to OFF Proceed to Step 12 Page 3 6 STEP PROCEDURE ILLUSTRATION 11 Connect positive lead of DMM to pin 3 of J5 A Observe DMM while placing power switch to ON Does DMM indicate 0 0 to 40 8 V when the red LED is illuminated Place power Place power switch to OFF f switch to OFF Fault lies in Fault lies in Drive Unit PC Disk Control Board Repairfler PC Board or replace Repair or replace Using two short lengths of wire carefully connect pins 1 and 2 of J7 to pin 1 of P7 Place power switch to ON Using a third piece of wire short sequentially between pin 1 of P6 and each of the test points indicated below Observe read write head while shorting each test point 12 1 J7 pin 4 A 2 47 5 3e 7 pin3 4 47 6 Verifv that the read write head moves toward the front of the VIC 1541 Repeat the procedure in reverse order and verifv that the read write head moves toward the rear Does the read write head move in the proper direction Place power Place power switch to OFF Fault lies in Drive Unit switch to OFF Proceed to
23. e Volts AC 3 Connect negative lead of DMM to pin 1 of Jl A 4 Connect positive lead of DMM to pin 4 of 41 B 5 Connect AC line between 29 the AC power receptacle and an AC outlet DO NOT CONTACT ANY AC DISTRIBUTION LINES 6 Place power switch to ON Does DMM display between 15 and 21 5 Vrms Proceed to Place power Step 3 switch to OFF Remove AC line cord Fault lies in Frame Assembly Re pair or replace Frame Assembly Page 3 3 PROCEDURE ILLUSTRATION Continue testing Frame Assembly as follows 1 Place power switch to OFF 2 Connect negative lead of DMM to pin 2 of J1 3 Connect positive lead of DMM to pin 3 of Jl 4 Place power switch to ON Does DMM display between 9 5 13 5 Vrms Frame Assembly Place power appears to be switch to OFF working pro Remove AC line perly Pro cord Fault ceed to lies in Frame Step 4 Assembly Re pair or replace Frame Assembly Place power switch to OFF Remove AC line cord Remove shield Disconnect J from MJ5 from P5 26 from P6 J7 from P7 and Jf from Proceed to Step 5 A SEE FIG 9 2 Reconnect 21 to Pl Connect line cord to 1541 Connect common lead of DMM to side of C52 A Set DMM to 20 VDC range Proceed to Step 6 Page 3 4 PROCEDURE ILLUSTRATION Place power swi
24. electronics novice can perform the procedures Troubleshooting consists of step by step procedures with accompanying illustrations Each step either asks a question or refers to the following step When a question is asked answer the question with a Yes or Below each question are two blocks labeled Yes No Follow the instructions in the appropriate block The instructions will either lead to another step or will isolate the problem to a particular sub assembly At this point the faulty sub assembly may be replaced or the sub assembly may be repaired down to the component level using the procedures in Troubleshooting Part 2 in the 1541 Maintenance Manual Page 3 1 8 2 TROUBLESHOOTING PART 1 PROCEDURE ILLUSTRATION Page 3 2 Remove AC line and serial bus cables Remove top cover Remove fuse from fuseholder Measure resistance of the fuse as follows 1 Set DMM Digital Multimeter to Ohms x 10 or Ohms x 100 2 Connect common lead of DMM to one end of fuse A 3 Connect positive lead of DMM to other end of fuse B Does DMM display less than 10 ohms Replace fuse with a new fuse of proper rat ing size Then proceed with Step 2 Install fuse and proceed with Step 2 TG AMA STEP PROCEDURE ILLUSTRATION Determine proper operation of the frame assembly as follows 1 Disconnect J1 from PI 2 Set DMM to measur
25. erence all test points before attempting any of the procedures in this Guide Jack Plug Numbers VIC 1541 1541 J1 P1 is J1 P1 22 2 5 J8 P8 24 4 is 7 23 3 J5 P5 is 25 5 J6 P6 is J6 P6 J7 P7 is J7 P7 J8 PY is J4 P4 J9 15 J9 1 3 Warnings Cautions and Notes Throughout this Guide are a number of Warnings Cautions and Notes A Warning means that there is a possibility of serious injury or even death to the technician if the Warning is not heeded A Caution means that there is a possibility of damage to the VIC 1541 if the Caution is not heeded A Note is intended to serve as an aid to the technician in understanding text or in following a procedure Page 1 1 SECTION 2 CALIBRATION Section 2 CALIBRATION 2 1 General No This Sestion contains step by step procedures for calibrating the WIC 1541 Only one calibration adjustment to adjust the speed of et L he disk to 300 rpm is provided in the VIC 1541 Perform the calibration procedure at the following intervals 1 Every 6 months 2 During the process of troubleshooting 3 After a repair action 2 2 Equipment Required 1 Small slotted screwdriver 2 Phillips screwdriver 3 Timing light Refer to Appendix B INOTE Any strobe light with an accurate frequency of 50 Hz 1 or 60 Hz 1 be used in place of the timing light 4 Blank floppy disk 5 1 4 inch single sided
26. gt N i SECTION 1 INTRODUCTION Section l INTRODUCTION 1 1 General The 1541 Maintenance Guide is produced to give a brief concise source of pertinent information necessarv for maintenance of the VIC 1541 and the 1541 disk drives Most of the information in this Guide has come from the 1541 Maintenance Manual which is also published Peltier Industries For those persons desiring more thorough coverage of the 1541 series of disk drives the 1541 Maintenance Manual is available through authorized dealers 1 2 1541 vs 1541 The VIC 1541 also known as the 1540 was the first generation of the 1541 disk drive Basically COMMODORE selected certain discrete components which were present on the VIC 1541 Disk Controller PC Board and combined them in custom IC s When they did this they renamed the disk drive the 1541 and changed the reference designators schematic identification of parts Functionally there is very little difference between the two versions Text in this Guide refers to the VIC 1541 Section 4 contains the 1541 Disk Controller Schematic and Disk Controller PC Board Parts Layout For a complete discussion of the differences between the two versions the 1541 Maintenance Manual may be consulted For the purposes of this Guide the following table and close inspection of the 1541 Disk Controller Schematic will enable 1541 owners to calibrate and troubleshoot their units 1541 owners must cross ref
27. igns of wear or damage Fault lies in Drive Unit Replace Page 3 9 SECTION 4 SCHEMATICS AND PARTS LAVOUT Section 4 SCHEMATICS AND PARTS LAYOUTS 4 1 General This section contains Schematics Parts Layout Drawings a Functional Block Diagram and an Interconnect Diagram These figures are provided for reference purposes following index is provided for user convenience Figure Title Page 4 1 Interconnect Diagram 4 2 4 2 Sub Assembly Identification 4 3 4 3 Functional Block Diagram 4 5 4 4 Disk Controller Schematic Sht 1 of 2 4 6 4 5 Disk Controller Schematic Sht 2 of 2 4 7 4 6 Disk Controller Parts Layout 4 8 4 7 Case Assy Schematic 4 9 4 8 Case Assy Parts Layout 4 9 4 9 Drive Unit Schematic 4 10 4 10 Drive Unit Parts Layout 4 11 4 11 Drive Unit Parts Layout Bottom 4 11 4 12 Drive Servo Circuit Schematic 4 12 4 13 Drive Servo Circuit Parts Layout 4 13 4 14 Frame Assy Schematic 115 4 14 4 15 Frame Assy Schematic 230 4 14 4 16 Frame Assv Parts Layout 4 15 4 17 1541 Disk Controller Schematic 1 of 2 4 16 4 18 1541 Disk Controller Schematic 2 of 2 4 17 4 19 1541 Disk Controller Parts Layout 4 18 4 1 TRACK SELECT P7 J7 DISK CONTROLLER DRIVE OPTICS 16 UNIT DRIVE MOTOR 5 READ WRITE J CASE ASSY SERIAL PWR BUS LED PWR LED SERIAL INPUT JI BUS POWER x FRAME ASSY J9 AC LINE Figure
28. of the following alignment systems is recommended 1 COMMODORE System This system is available from Commodore Business Machines Inc Customer Service Dept 1200 Wilson Dr Westchester 19380 Alignment disk 970160 01 5130 Test program disk 970154 01 S 26 Service manual 9900445 5 25 Total 5181 above items plus dual trace oscilloscope are required to align a disk drive using the COMMODORE system 2 Peltier Industries System This system is available from Peltier Industries Inc 735 N Doris Wichita Ks 67212 Disk Alignment Svstem DAS 1541 539 95 The svstem includes Alignment reference disk Control disk Instruction manual Video detector The above items plus a 3 1 2 digit 100 Kohm digital voltmeter are required to accuratelv align a disk drive using the Peltier Industries Svstem Page 2 4 2 5 2 Equipment Required 1 Alignment standard use a factory recorded disk which has not been written to since purchase or a disk which has been formatted on a VIC 1541 which is known to be in proper alignment 2 Digital Voltmeter 3 Video detector see Appendix A 2 5 3 Preparation for Mechanical Alignment Detailed disassembly assembly instructions can be found in the 1541 Maintenance Manual 1 Remove all external cables from VIC 1541 2 Remove upper cover 3 Remove RFI Shield 4 Remove Disk Controller PC Board 5 Remove Drive Unit 6 JI
29. r running 10 OPEN 15 8 15 0 2 8 2 OPEN 8 8 8 20 PRINT 15 B P 8 0 PRINT 15 UA 2 0 16 1 30 FOR 1 9 READ Y 40 PRINT 8 Y 50 NEXT X 60 PRINT 15 M E CHRS 0 CHRS 5 b 0 STOP 80 DATA 173 0 28 9 4 141 0 28 96 a u 9 Type RUN lt Return gt ati 10 Loosen two screws See Figure 5 2 securing stepping motor housing to drive unit Do not remove screws Screws should be just loose enough to permit rotation of the stepping motor housing il Rotate stepping motor housing while observing DVM display Voltage reading on DVM will increase or decrease while rotating stepping motor housing Correct position for stepping motor housing is the position which produces the largest voltage reading on DVM Tighten the two screws when this position is reached 12 Turn off DVM disk drive and computer 13 Disconnect all cables and test accessories from disk drive Page 2 6 14 Apply small amount of Glyptol or 1 polish to the two screws securing stepping motor housing to keep them from coming loose 15 Reassemble the VIC 1541 Stepping motor housing screws 2 places N Stepping motor housing Figure 2 2 Head Alignment Adjustment Page 2 7 E jm 2 6 Mechanical Alignment of Track 41 Stop 2 6 1 General This procedure adjusts the Track 41 Stop Track 41 Stop is used by the computer in the VIC 1541 for only two purposes 1
30. tch to ON Measure tests points in table below Touch positive lead of DMM to indicated test point Verifv that each measurement is within the minimum and maximum limits given Test Point Min Max P8 pini 4 6V 5 25V P7 pinl B 11 4 12 6V P7 pin2 C 11 4V 12 6V P5 pin2 D 11 4 12 6V P6 pin8 E 4 75V 45 25V P6 pin2 F 4 6V 45 25V Are all measurements above within limits specified Place power Place power switch to OFF switch to OFF Proceed to Remove AC line Step 7 cord Fault lies in Disk Controller PC Board Repair or replace Connect Jj to Pg switch toON gi 15 green LED illuminated Place power switch to OFF Remove AC line cord Fault lies in Case Assembly Repair or replace Place power Place power switch to OFF Proceed to Step 8 Page 3 5 PROCEDURE ILLUSTRATION Connect J6 to P6 switch to ON Place power Does red LED come on momentarily Proceed to Step 9 Place power switch to OFF Proceed to Step 10 Using a short piece of carefully short pin 10 of UF2E to pin 1 of 6 while observing the red LED Error Access LED UC3 vr ian m Di 821509 H LS24 nir Does red LED illuminate 3 Place power switch to OFF Fault lies in W r Drive Unit Repair or replac
31. to Pl J to P2 05 to P5 J6 to P6 and JI to P7 in such a manner that access is still allowed to the stepping motor mount screws See Figure 2 2 CAUTION DO NOT ALLOW PATHWORK ON DISK CONTROLLER PC BOARD TO CONTACT THE FRAME OR DRIVE UNIT ASSEMBLIES USE AN INSULATING RUBBER MAT IF NECESSARY TO INSULATE THE DISK CONTROLLER PC BOARD FROM THESE ASSEMBLIES P 7 Connect video detector between DVM and pins 7 and 8 of Y 287571724 NOT e dd 8 Reriove any Glyptol or other substance from stepping motor mount screws See Figure 2 2 2 5 4 Head Alignment 1 Connect VIC 20 COMMODORE 64 to video monitor or TV Refer to computer User s Guide for proper connection 2 Connect serial bus cable between P3 on VIC 1541 and serial bus connector on VIC 20 COMMODORE 64 Page 2 5 3 Connect power cord between J9 1541 and outlet USE EXTREME CARE TO AVOID CONTACT WITH FRAME COMPONENTS HIGH AC VOLTAGE POTENTIALS ARE PRESENT DURING CALIBRATION THESE VOLTAGE POTENTIALS CAN CAUSE BODILY INJURY OR EVEN DEATH 4 Place VIC 1541 power switch to ON 5 Apply power to VIC 20 COMMODORE 64 6 If a VIC 20 is the computer being used enter the following command OPEN 15 8 15 UI CLOSE 15 lt Return gt 7 Insert disk which will be used as the alignment standard into the VIC 1541 8 Enter the following program into the computer This program will place the head on track 16 and will leave the drive moto
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