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INDUS GT_Field Service Manual

1. ine cxuanedandesaksaneane xatvouxhansseunnanaenne 4 6 4 7 D O N BS 4 6 4 8 FDC TYPE 4 7 4 9 WRITE sscisacsicsdcasnszassxauanorannsansxacunaeunensaunceusaasaxscascnenaneksensseubendussentadansusiakanasnndacexaueunensaunsanasane 4 7 4 10 TRACK ZERO ADJUSTMENT ssisesscicsisistcacceccascecsnsceranncotessesstadesancnaseadesdessettnedeceactesdestessacacntstess 4 8 4 11 FORMAT DISKETTE nitro rpnt ex ERR FER SEE RR ERE RR RENS PENEVRRRRRE REM NR 4 8 4 12 LED TEST 4 8 4 13 DRIVE M 4 9 AVA ROM VERSION n ions URS ERR RR NEEDS REX REO 4 9 4 14 1 VERSION 1 00 TO 1 10 CHANGES 4 10 4 14 VERSION 1 10 TO 1 20 CHANGE Sumuinen nanain 4 10 4 15 POSITION HEAD 2 6 2i 3icoico isa nana E a S3 SERRE nri Roo Ro aoc Rc aS RSEN ARKA ATA NAATA TANOAN 4 12 4 16 CHECK 4 13 CHAPTER 5 5 1 5 1 INTRODUCTION 5 1
2. 5 6 5 8 2 DRIVE WILL NOT CONFIGURE DENSITY VIA FRONT 5 6 5 8 3 DRIVE WILL NOT CONFIGURE DENSITY VIE REAR SWITCHES essere terne nentes 5 6 5 9 DRIVE WILL NOT SELECT DRIVE NUMBER rri tnnt ten ttis 5 6 5 10 FRONT PANEL LEDS NOT OPERATING PROPERLY eene 5 7 CHAPTER OO0O0OO702 i 6 1 REPAIR GUIDELINES eese nee niin nnn nnn nnne tete ten tei ea Ro AE RIA 6 1 6 1 OVERVIEW OF REPAIR GUIDELINES eese niente inet inre nn t i 6 1 6 2 THE TANDON DRIVE MECHANISM erint niter tnnt nnt e e 6 1 6 2 T VISUAL INSPECTION 3 itai eredi utet tee ue P prd uit eeu oe cutie ds e toe uat 6 1 6 2 2 EQUIPMENT REQUIRED iacu ule Ra uod egt ac ede PUn Bon nes HOM PO RR E DH PO AR 6 2 6 2 3 POWER DRIVE SELECT CHECK dedica s medie e dO rte eie ed bn endorse dad dn 6 3 6 2 4 WRITE PROTECT OUTPUT CHEGR inte ende e 6 4 6 2 5 RADIAL TRACK ALIGNMENT AND ADJUSTMENT esee eene tentent tnnt to tts tenen tn ttn tos to 6 6 626 AZIMUTH cei tede Tt doch tede 6 12 6 27 5 ih ete iet uri e Ee ER EH Seiten ud ttes 6 16 6 2 8 TRACK O STOP ADJUSTMENT Siminmi a eei ert oce estetico ee ebrietas ee 6 16 6 2 9 COMPLIANCE CHECK AND 6 18 6 3 MOTOR SPEED ADJUSTMENT erre nenne
3. eeesen entente ener 2 19 CHAPTER 3 1 3 1 WHAT TO DO FIRST tnt tnt thi thi ta tni tud 3 1 3 2 POWER SUPPLY PROBLEMS esent tnnt th tette tudin iini inani tn tud tna tata a nnn 3 2 3 2 1 EXTERNAL POWER TRANSFORMER eeseeeenenn enter tenen tenen sensn sensn 3 2 3 2 2 POWER INPUT CONNECTOR o aate hc Abe RIA Ide p e dedi ed abies ene 3 3 3 2 3 INTERNAL POWER ELEMENTIS inet mp 3 3 323 1 DUST COVER WILL NOT OPEN a nete eet eeu RU eid ene iei ele t te elds 3 4 3 3 2 MISSING OR BROKEN SPRINGS esses tenen tenen tenet tenen 3 4 3 3 3 BROKEN WIRES CONNECTORS nai ianiai 3 5 313 5 D 314085200 Py 3 7 3 3 6 READ WRITE HEAD GUIDE RAILS S uerg 3 7 1 Field Service Manual 3 4 LEVEL ONE INTERNAL DIAGNOSTICS eere 3 8 SAL 1Z80A PROCESSOR TESTS grms aii 3 9 3 4 2 ROM CHECKSUM TEST 3 9 3213 CIZMT QUICK TEST 3 10 3 4 4 C2 H2 Z80A INDEX REGISTERS TEST ssessssssssssssssssssssssssssssssssssasssasssssssssssssessssssssssssssssns 3 10 3 4 5 C3 H3 FLOPPY DISK
4. 5 6 WRITE ERRORS 1 Check WRITE PROTECT output see section 6 2 4 2 Replace the NE555P 741 574 and 741 526 ICs 3 If problem persists replace the Analog Board 4 If problem is still present the head carriage assembly probably is bad Replace the Tendon Mechanism 5 7 FRONT PANEL SWITCHES MALFUNCTIONING 1 Check each switch for any broken or worn pieces 2 Ifthe switches are in good condition then replace the front panel 3 Ifthe problem is still present replace the WART Board Section 5 Page 5 5 GT Field Service Manual 5 8 DRIVE WILL NOT CONFIGURE DENSITY 5 8 1 Drive Will Not Configure Density vie Software 1 Run the self tests as outlined in section 3 4 amp 3 5 2 Ifthe self tests pass replace the EPROM 3 Ifthe problem is still present replace the WART Board 5 8 2 Drive Will Not Configure Density via Front Panel 1 Referto section 5 6 on switch malfunctioning 5 8 3 Drive Will Not Configure Density vie Rear Switches 1 Check for broken DIPswitch leads 2 Ifleads are broken replace the DIPswitch 3 Replace wart Board 5 9 DRIVE WILL NOT SELECT DRIVE NUMBER 1 Check for broken DIPswitch leads on rear of drive 2 Ifany leads are broken replace the DIPswitch 3 Replace wart Board Section 5 Page 5 6 GT Field Service Manual 5 10 FRONT PANEL LEDS NOT OPERATING PROPERLY 1 Replace the front panel 2 Ifthe problem is still present replace the EPROM 3 I
5. COMPLIANCE SPRING HAS THREE TENSION POSITIONS ANGLE OF SLOT DETERMINES SPRING TENSION UPPER ARM AND COMPLIANCE SPRING Section 6 Page 6 20 GT Field Service Manual 6 3 Motor SPEED ADJUSTMENT The drive motor speed test checks to see if the speed is within the specified tolerance Theoretically the motor speed should be at 288 RPM plus or minus four RPM The recommended speed is 288 RPM plus or minus one RPM STEP 1 Insert a diskette into the drive STEP 2 Select the Motor Speed option of GT DOC STEP 3 Select the Index Mark speed check STEP 4 Locate R31 on the Analog Board see Figure 6 9 This is the speed control pot STEP 5 Adjust R31 until the motor speed is within 288 RPM plus or minus RPM Section 6 Page 6 21 WQWS5 tT Field Service Manual Figure 6 9 Location of Speed Control Pot INDUS GT ATARI MODEL Section 6 Page 6 22 GT Field Service Manual 6 4 REPLACING INTEGRATED CIRCUITS When replacing any integrated circuits it is recommended that an IC extractor insertion tool be used Screwdrivers and pocketknives can cause extensive damage to the pins of an IC It is recommended that before you replace an IC that you check it for any bent or misaligned pins Also make sure that the IC is firmly seated in its socket If you find a bent or misaligned pin gently straighten the pin insert the IC back in its socket and recheck the drive In some cases this will fix the proble
6. 5 2 PRELIMINARY TROUBLESHOOTING 5 5 2 5 3 DRIVE WON T STEP OR STEPS 5 2 5 4 DRIVE MOTOR 5 3 5 11 DRIVE MOTOR WON T ROTATE susan einen tallo oto duc EDU OUR 5 3 5 12 DRIVE SEERDUNSIABIE omisiunea pulus nn 5 3 5 4 3 DRIVE SPEED STABLE BUT OUT OF TOLERANGCE 5 3 1 Field Service Manual 5 5 READ ERRORS ET YX 5 3 5 5 1 READ ERRORS ALL TRACKS ee e eR Laan RD t sp a e iain 5 3 5 5 2 READ ERRORS RANDOM TRACKS uu 5 4 5 5 3 READ ERRORS INSIDE TRACKS tente tte tnter a iai ga er posae stood 5 4 5 5 4 CANNOT READ PREWRITTEN DATA CAN READ SELF WRITTEN 5 5 5 5 5 CANNOT READ DISKS WRITTEN BY THIS DRIVE DISKS CAN BE READ BY OTHER DRIVES 5 5 5 6 WRITE ERRORS T 5 5 5 7 FRONT PANEL SWITCHES MALFUNCTIONING erret terrent nri 5 5 5 8 DRIVE WILL NOT CONFIGURE DENSITY eese nennen nnne teinte ten tti rens 5 6 5 8 1 DRIVE WILL NOT CONFIGURE DENSITY VIE SOFTWARE eeeeereeten tente treten tnnt
7. Checkthe connectors for placement and seating 7 Checkfor damaged or missing components 8 Make sure that a diskette can be inserted and removed Section 6 Page 6 1 GT Field Service Manual 6 2 2 Equipment Required Except where noted otherwise the following equipment is required to perform the checks and adjustments discussed in this section INDUS GT power supply A number 1 Phillips screwdriver Jeweler or precision flat blade screwdriver for motor speed adjust Spring inserter remover Flat blade screwdriver 3 16 inch tip GT DOC or equivilant diagnostic program Digital voltage meter DVM A dual channel wideband oscilloscope Hewlett Packard Model 174BA or equivalent A certified alignment diskette Dymek Model DK 501 05 or Dysan Model 224 2 10 A gram gauge MO e Your test equipment should be calibrated properly or you may not get reliable results from the tests called out in this section Most test equipment has a calibration sticker on it somewhere Check the expiration date or the calibration period Get any out of cal equipment calibrated before performing the tests in this section Section 6 Page 6 2 GT Field Service Manual 6 2 3 Power Drive Select Check The drive select check verifies that the BUSY LED can be illuminated and that power is being supplied to the drive The following steps are required to perform this test STEP 1 Turn the power
8. Z80As IRQ line The test fails if the FDC has not responded Section 3 Page 3 10 1 Field Service Manual 10 11 12 13 14 15 16 The FDC is issued a FORCE INTERRUPT command to clear the FORCE IMMEDIATE INTERRUPT condition The Z80A once again waits for 52 microseconds to allow plenty of time for the FDC to respond The FDC status register is read to clear the FDC interrupt condition The Z80A waits for another 52 microseconds to allow time for the FDC to respond The FDC INTRO line is again tested to make sure the FDC has cleared it The test fails if the FDC has not responded The FDC track sector and data registers in that order are loaded with 00H 01H and 02H respectively Then the data sector and track registers in that order are tested to see if the pattern has changed The test fails if there is a mismatch If all three patterns match the test is repeated with 01H 02H and 03H respectively This testing continues until the last pattern used is FFH 00H and 01H respectively The FDC track register is copied to the data register and a seek command is issued This causes the FDC to seek to the track it is already on This test verifies that the WD1770 is in Mode 1 and that the IP is reselected in the status register This test isn t required with the WD2797 The FDC index pulse IP line is set active The Z80A delays for slightly more than 20 microseconds to give the FDC time t
9. an excessive amount of noise during this test The position head routines should function properly whether or not there is a diskette is in the drive and regardless of the density of the diskette or the drive s current configuration Section 4 Page 4 12 1 Field Service Manual If the drive doesn t track between track 00 and track 39 then the stepper motor or the motor control electronics may be defective If the problem narrows down to the stepper motor you will have to replace the TANDON drive mechanism If the drive exhibits excessive noise during option 2 then lubrication of the drive spindle the read write head guide rails and possibly the stepper tracks are probably in order 4 16 CHECK DISK This routine verifies that the drive can read any sector on a diskette In a sense it also serves as a diskette media verification test when you enter this menu selection you will be prompted to enter the starting sector number and then the ending sector number Follow each entry with the RETURN key If you press the RETURN key instead of a number for the starting sector the entire disk will be verified Pressing Just a RETURN in response to the second prompt will return you to the main menu When the test is complete it displays each error found and the sector in which the error occurred At any time during this test you can abort it by simply pressing the ESC key This routine is independent of any DOS and will function properly
10. certain pins shorted together as follows e Pins 1 2 and 7 shorted CLOCKIN CLOCKDUT and CMD signals e Pins 3 5 and 10 shorted DATAIN DATADUT and ROY 5V signals Allremaining pins should be left open This special connector should be inserted into one of the WART peripheral connectors It does not matter which connector you use but no cable should be attached to the other connector Without this special connector the LEVEL TWO internal diagnostics will always fail Section 3 Page 3 12 GT Field Service Manual 3 5 0 How To Invoke The LEVEL TWO Tests The LEVEL TWO internal diagnostics are invoked as follows 1 Turn the disk drive OFF 2 Disconnect any I O cables from the drive 3 Plugthe test connector into one ofthe I O ports on the drive it doesn t matter which port 4 Press and hold down the TRACK ERROR and DRIVE TYPE buttons on the drive s front control panel 5 While still holding the three control buttons turn the disk drive power ON If you perform this test on a good drive the drive s LED display will flash through a series of test codes as described in the previous section and appear to stop with a display of C5 If you wait a moment the display will suddenly switch to displaying a lower case i e cb This display will alternate between and for a long time This is the normal sequence of displays for a good disk drive 3 5 1 C4 H l Bus Interface Test The WART tes
11. coding resulted in the drive functioning improperly when a sector in the range of 721 to 1848 was requested for either read or write operations Earlier versions of the EPROM would return a command frame error instead 4 15 POSITION HEAD This menu selection gives you three options The options are numbered 0 1 and 2 Option 0 clears the disk drive of any previously issued commands and restores the read write head to track zero This function is also performed automatically whenever you exit this selection by pressing the ESC key Option 1 positions the read write head to any track on the disk You will be prompted to enter a number between 0 and 39 for the desired track Numbers outside this range will not be accepted Once you have entered the desired track number you must press the RETURN key to initiate the test Option 2 causes the drive to repeatedly move the read write head between two specified tracks You will be prompted to enter the first starting track Enter it and press the RETURN key Next you will be prompted to enter the second track Enter it and press the RETURN key The usual restrictions on the legal track numbers still apply The commands will then be sent to the drive to begin the test Option 2 could be used as a rail noise test since this routine causes the read write head to seek between two tracks indefinitely If the drive s read write head guide rails are in need of fresh lubrication you should be able to hear
12. density and a half in describing this operating mode This mode is also called Enhanced density The double density mode of operation is true double density in the usual industry usage of the term It consists of 40 tracks with 18 sectors on each track and 256 bytes per sector Most of the DOS available for double density make about 179K of storage space out of the maximum 184K available on the disk The disk drive is configurable to any of the three density modes either from the front panel of the drive or by software commands sent across the serial I O SIO bus In addition the drive has a default select switch located on the back panel that will cause the drive to automatically configure itself tor either single or double density when the unit is powered up Another configuration feature is that the drive can sense when a new disk has been inserted and it will re configure itself for the density of the new disk during the first attempt to access the disk drive The drive uses a relatively simple process to automatically determine which density configuration it is supposed to operate in when power is first applied to the drive the on board Z80 microprocessor runs a short series of self tests and then examines the setting of the third pole on the back panel DIP switch The normal default configuration is single density but the DIP switch can be set to cause this default to be double density instead This provides drives that are not in the num
13. displayed on the screen as follows WD1770 or WD1772 Or WD2793 or WD2797 Ifthe WD177X series is displayed then reboot the drive with the extended internal tests If the drive passes the extended internal diagnostics reboot the drive normally and rerun this test If WD177X is again displayed then the drive will have to be opened Once opened examine the WART board and visually verify the FDC type If the FDC chip is in the WD279X series then replace the EPROM Although provision has been made to include the WD177X series of FDC in this program such devices have not been used yet in any of the INDUS GT Atari disk drives 4 9 WRITE DATA This is a general read write test which writes a series of numbers to random sectors on a diskette The drive must be configured to the same density as the diskette you are using in the test Make sure you use a scratch disk that does not contain anything you wish to save This routine will overwrite any data already on the disk If error codes 144 or 139 appear then verify that the drive configuration and the format of the diskette are the same Next verify that you are using a formatted diskette Last verify that the write protect switch on the front panel is not ON If errors persist then re initialize a diskette with the GT DOC format option If drive errors F9 or F7 occur during the formatting process see section 5 for additional troubleshooting on the write protect circuit Section 4 Pag
14. on has a version number of 1 00 or 1 10 then it should be replaced immediately with the latest version of the device The latest version to date is 1 20 There are significant differences between the three versions The following paragraphs detail the major differences Some of the tests such as the write Data and the Check Disk routines will not function properly in the DUAL density mode if the EPROM is not 1 20 due to a programming error in the EPROM code Section 4 Page 4 9 GT Field Service Manual 4 14 1 Version 1 00 to 1 10 Changes Synchronous Communications A special high speed communications protocol was added to the EPROM s code This new code is supposed to be used by the SYNCHROMESH high speed data transfer mode of the disk drive As of this writing this high speed mode is still in development BUSY LED Stuck ON fix If the drive was currently busy and the computer abandoned it to communicate with another device the drive would clear back to the non busy mode polling various gadgets and leave the busy LED lit This error was corrected in EPROM version 1 00 4 14 2 version 1 10 to 1 20 Changes Write verify error display Previous EPROM versions would display an up down A followed by a right side up 2 when the display was supposed to be a P PUT error number 9 This was nothing more than an error in the pattern which the EPROM sent to the LED display The P9 error indicates a verify error when r
15. panel and recheck it for proper operation using GT DOC STEP 3 If the same results occur then replace the EPROM and recheck it for proper operation STEP 4 If the same results occur replace the WART board 6 7 REPLACING CONNECTORS When replacing connectors take care not to damage any of the wires When replacing connectors replace only one wire at a time That way no confusion will result over which wire goes in which hole in the connector Section 6 Page 6 25 GT Field Service Manual Chapter 7 Schematics amp Drawings Section 7 Page 7 1 GT Field Service Manual Chapter 8 Parts Laiasts Section 8 Page 8 1
16. regardless of how your DOS is configured However this routine will not function properly on sectors in the range 721 to 1040 on an INDUS GT that has a version 1 00 or 1 10 EPROM Section 4 Page 4 13 GT Field Service Manual Chapter 5 Troubleshooting Guidelines 5 1 INTRODUCTION This section contains general troubleshooting information We will assume that you have read and understand the material in sections 1 0 2 0 and 3 0 The first step in troubleshooting is to verify that the power supply and interface to the disk drive are functioning properly Next try to isolate the trouble to the electronic electromechanical or mechanical components of the INDUS GT disk drive see section 3 0 Table 5 1 is a list of some trouble symptoms referenced to paragraphs that include possible causes and suggested fixes TABLE 5 1 TROUBLE SYMPTOMS TOPIC Preliminary Troubleshooting Steps Drive won t Step or Steps Erratically Drive Motor Won t Rotate Drive Speed Unstable Drive Speed Stable But Out of Tolerance Read Errors All Tracks Read Errors Random Tracks Read Errors Inside Tracks Cannot Read Disk written On Another Drive Cannot Read Disk written By this Drive Write Errors Front Panel Switches Malfunctioning Drive will Not Configure Density Drive will Not Select Drive Number Front Panel LEDs Not Operating Properly Section 5 PARAGRAPH 9 2 5 3 541 5 4 2 5 4 3 5 5 1 5 5 2 5 5 3 5 5 4 5 5 5 5
17. table below lists the ID codes on the board and the actual code that is used on each connector Note that the labels used on the board itself match those used in the schematics see Section 7 0 Board ID Connector ID Number of Pins J1 20 5 J2 NONE 20 J3 J3 6 J4 J1 4 This confusion in the connector IDs will also occur with some of the other subassemblies so don t be surprised when we show you another table like this one elsewhere in this manual Section 2 Page 2 8 GT Field Service Manual 2 3 5 Removing the TANDON Drive Assembly The TANDON disk drive mechanism is mounted to the main chassis with four small screws two on each side After you have made sure that the front panel assembly has been loosened remove the tour mounting screws with a Phillips screwdriver If you have not already disconnected the 20 pin bus connector to the analog board do so at this time The TANDON mechanism should lift easily out of the main assembly Note that there are still three small connectors attaching the mechanism to the board below the WART board Gently disconnect the three small 4 pin connectors They should be labeled J7 9 and 12 Note once again that the labels on the connectors do not necessarily match the labels on the board The table below shows you which connectors go where Board ID Connector ID J7 J7 or J11 J8 J12 J9 J9 Some versions of the drive may also be on
18. then trying to read the pattern back It the pattern read back matches the original pattern written to the RAM the test is repeated using the reverse pattern AA55H If the pattern read back on the second pass is okay the RAM is passed as good If this test fails an H code will be displayed on the disk drive s LED display 3 4 4 C2 H2 Z80A Index Registers Test This test is separate from the initial Z80A tests that were performed earlier in the power up sequence The Z80A index registers IX and IY are not tested until after the quick RAM test because the index registers test relies upon the RAM during the testing Since the main Z80A registers will have had to pass their testing before you could get this far an index register test failure will not HALT the Z80A processor Instead if this test fails an He error code will be displayed on the drive s LED display and the drive will Halt 3 4 5 C3 H3 Floppy Disk Controller Test The floppy disk controller FDC is the heart of the disk drive This test runs through a complex series of routines to checkout the FDC The test proceeds as follows 1 The UART issues a FORCE IMMEDIATE INTERRUPT command to the FDC 2 The Z80A goes into a short time delay loop for 52 microseconds This is the maximum time the WD1770 should require to respond The WD2797 is alot faster 3 The FDC INTRQ line is tested to see if the FDC has interrupted Note that the FDC INTRQ line is not tied to the
19. to Figure 2 6 to see how the latch is mounted You must remove the display control board before you can get this latch out Once you have the display control board out remove the single Phillips screw you will find in the center of the front panel assembly and the door latch will easily pull out Be careful to catch the small spring that is under the latch 2 3 9 Removing the WART Board This is the last stage in the disassembly or an INDUS disk drive You should have the main chassis with the WART board mounted in the bottom of the other assemblies should have been removed by now SIX Phillips screws secure the WART board You will find one screw in each of the four corners of the board Go ahead and remove these four screws Now look at the rear part of the board near the main power switch Find the two voltage regulators VR1 and 2 see Figure 2 7 Remove the Phillips screw from each of these components The MART board is now disconnected from the chassis A little physical maneuvering will enable you to work the board free from the chassis see Figure 2 3 Section 2 Page 2 14 WQWS5 tT Field Service Manual FIGURE 2 7 Parts Layout of the WART Board 0 0 wx contro sr 3 L n JB I k zw 0 Ss 0 200 te CS n F 6 0 UL ID LN i fo 5 IFoo INDUS GT ATARI MODEL MOTHER Section 2 Page 2 15 WQWS5 tT Field S
20. two screws with a Phillips screwdriver and pull the dowel pins out You may have to use a small pair of pliers to get the pins out Once you get the dowel pins out the Plexiglas dust cover will almost fall out into your hands See section 2 4 3 for instructions on how to re install a new dust cover 2 3 7 Removing the Front Display Control Board This step is necessary only if you are replacing either the display control board or the front door latch The display control board is mounted inside the front panel assembly as shown in Figure 2 6 This board has all of the LED displays as well as the PC bubble switches which are actuated by the front panel push buttons First make sure you have disconnected the ribbon cables from the WART board J10 and J11 The display control board is held in place by two small Phillips screws You do not need to actually remove these screws loosening them should allow you to remove the display control board We do NOT authorize any repairs to this board If you have a switch or LED failure simply replace the board with a new one and ship the defective board back to INDUS for a replacement Section 2 Page 2 12 WQWS5 tT Field Service Manual FIGURE 2 6 Exploded View of Front Control Panel INDUS GT ATARI MODEL EXPLOOED view Section 2 Page 2 13 GT Field Service Manual 2 3 8 Removing the Door Latch The door latch is the slide catch that secures the Plexiglas dust cover Refer back
21. 6 5 7 5 6 5 9 5 10 5 1 GT Field Service Manual 5 2 PRELIMINARY TROUBLESHOOTING STEPS The following preliminary steps should be performed first when you are trying to isolate a suspected malfunction 1 Inspect the power and I O connectors Make sure that they are properly installed and that they have no broken pins Also make sure that their mating cables plug in properly Verify that the dust cover lifts smoothly and that the front latch opens and closes easily The head arm should lift when the front latch is open Verify that a diskette can be easily inserted and removed from the drive Take the main housing off of the drive and make sure that all of the circuit board connectors are properly seated and have no broken wires Check for any loose or missing hardware Manually rotate the drive hub it should rotate freely Check the circuit boards for any damaged or missing components Attach an INDUS power supply to the drive and turn the power ON The LED display should flash through a series of codes beginning with C then stop on track 00 for a few seconds and finally come to rest on track 39 The drive motor should come on during this sequence and turn OFF at the end Note any deviation from this sequence 5 3 DRIVE WON T STEP OR STEPS ERRATICALLY Verify that the head cable does not interfere with carriage movement 1 2 Replace the 5 75437 QUAD PERIPHERAL DRIVER on analo
22. ANUS 51 Field Service Manual tT Field Service Manual CHAPTER EE M 1 1 GENERAL DESCRIPTION 1 1 1 1 INTRODUCTION 1 1 1 2 PURPOSE OF EQUIPMENT eren 1 1 1 3 PHYSICAL DESCRIPTION 1 3 1 4 FUNCTIONAL DESCRIPTION 1 6 1 4 T POWER SELF RESTS oci t pec t cen ra ere ee D Oe 1 6 1 4 2 MULTIPLE DENSITY iaiia tentent tnnt tret tret tret tte ta tte ta ttes ttes ttes teta ttes ttes tesa nn 1 6 1 43 INPUT amp OUTPUT issn eerte eh t e e B e eas 1 9 1 4 4 AcTIVITY CONTROL PANEL DISPLAYS ee 1 9 1 5 REPAIR REPLACEMENT 1 10 pm 2 1 2 1 EQUIPMENT aaan ara Taaa EAEAN 2 1 2 2 CAUTIONARY 2 4 2 3 DISASSEMBLY amp 2 5 2 31 REMOVING THE REAR PANEL 2 5 2 3 2 REMOVING THE MAIN En 2 5 2 3 3 REMOVIN
23. CONTROLLER TEST 3 10 3 5 LEVEL TWO INTERNAL DIAGNOSTICS rere 3 12 3 5 0 How INVOKE THE LEVEL TWO TESTS sssssssssssessessssssessesssssessessssuessusssessessessssseesesnsessesaeensess 3 13 351 EDAM BUS INTRBEACE i ani len b aee as basta nis cn tain dic 3 13 3 5 2 S N INTERRUPT CIRCUITRY T BST erbe tco 3 14 3 5 3 LOMG EXTENDED RAM TEST 3 15 CHAPTER 4 4 1 DIAGNOSIS WITH GT DOC we rs usk ah Kup EORR MERE REOR RES Tanina Ainaa raan DSREKR PERDER 4 1 4 1 OVERVIEW OF GT DOC eterne nentur neo Fun nh cusa traen anra taa neu RE Baur USERS 4 1 4 2 THE COMMAND MENU 4 2 4 3 DISK DIRECTORY 4 3 4 4 MOTOR SPEED soniais X 4 3 4 5 DRIVE CONFIGURATION INQUIRY e eeeeeeeeereenenn 4 5 4 6 DBIVESELEGCT
24. DED A medium size Phillips heed cross point screwdriver is all you will need for most of the disassembly and re assembly of one of these drives You will also find a smell Jeweler s screwdriver useful in removing end reinstalling the few springs you will encounter If you are going to be removing any of the IC s you should use the proper tools to avoid damaging any of the pins For your convenience here is a list of suggested tools Medium sized Phillips screwdriver Small Jeweler s screwdriver 24 40 pin IC extractor EX 2 extractor tool 16 pin IC extractor EX l extractor tool 48 pin IC insertion tool MOS 40 CMOS safe inserter 24 pin IC insertion tool MOS 24 28 CMOS safe inserter 16 pin IC insertion tool INS 1416 DIP IC inserter Anti Static Wrist Strap connected to a good ground You should be able to find all of these tools or their equivalents at your local electronics supply store Section 2 Page 2 1 WQWS5 tT Field Service Manual FIGURE 2 1 Exploded View of INDUS GT Disk Drive INDUS GT ATARI MODEL PPL nne Section 2 Page 2 2 WQWS5 tT Field Service Manual FIGURE 2 2 Exploded View of Front Control Panel Section 2 Page 2 3 GT Field Service Manual 2 2 CAUTIONARY NOTES There ere certain common sense cautions that any technician should be aware of when working with modern solid state electronics as well as a few special cases applicable to this disk drive in parti
25. ED does not extinguish when the above test is run replace the WART board Repeat the test to verify proper operation of the drive 6 2 4 write Protect Output Check The write protect output check establishes the correct operation of the write protect circuit i e that the write electronics are disabled when a write protected diskette is used STEP 1 Connect the positive and negative test probes from your DVM to pins 3 and 4 respectively of connector J7 on the WART board board ID J7 STEP 2 Set the DVM to the 20 VDC scale STEP 3 Insert a write protected diskette The DVM should display a reading between 4 4 VDC and 5 0 VDC STEP 4 Remove the diskette from the drive The DVM should display a reading between 0 0 and 0 8 VDC NOTE A defective WART board connector or a broken wire can be responsible for a write protect problem The following steps will help isolate the write protect problem STEP 1 Disconnect connector 7 from the UART board STEP 2 Connect the plus and minus test probes of a DVM to connector J7 on the WART board see Figure 6 1 Section 6 Page 6 4 GT Field Service Manual FIGURE 6 1 DVM Connection to WART Board Section 6 Page 6 5 GT Field Service Manual STEP 3 With the DVM set to the 20 VDC scale observe that the voltage is between 4 4 VDC and 5 0 VDC If STEP 3 fails replace the WART board amp repeat the test If STEP 3 passes then go on to STEP 4 STEP 4
26. Field Service Manual The spring in the door latch causes the slide switch to move back into the latched position If the door latch does not function properly the cause may be a missing spring or the retaining screw for the latch may be too tight The spring on the back side of the dust cover is what causes the cover to open when the door latch is released If the dust cover does not open properly This spring may be missing The spring near the read write head pulls a felt padded arm down on the diskette during normal read write operations This pad makes sure that the read write head is snug against the diskette If this spring breaks you will get unreliable operation during virtually all read and write functions The spring near the locking bar on the TANDON mechanism is the diskette ejector spring If this spring is missing there will be very little resistance when you try to insert a diskette into the drive and the diskette will not automatically eject when you open NE locking oar Some drives have a fifth spring attached to a plate near the read write head This spring serves no useful purpose and you will find it has no effect on drive operation whether the spring is there or not You may ignore this spring 3 3 3 Broken wires Connectors The most likely connectors to have problems are the two serial I O connectors on the rear of the drive The most common problem is that the user will be careless when plugging an interface c
27. G THE FRONT PANEL ASSEMBLY c scssssessssecssseessseessecenssseaeaseasacensaseneaseneaseasaseasaseaeaseasasensaeas 2 6 2 3 4 REMOVING THE TOP ANALOG CIRCUIT 2 6 2 3 5 REMOVING THE TANDON DRIVE ASSEMBLY eere treten tnnt to tte tton tonto tts tonto toas 2 9 2 3 6 REMOVING THE PLEXIGLAS COVER esses ees seen tenen en tenen tenen tenen 2 9 2 3 7 REMOVING THE FRONT DISPLAY CONTROL BOARD sese tte tnnt tentent tnnt tens 2 12 2 3 8 REMOVING THE DOOR 2 14 2 3 9 REMOVING THE WART BOARD a 2 14 2 4ASSEMBLY INSTRUCTIONS 2 17 INSTAELEING THE WART BOARD ier arre ite RR OPER Ee AREE Rain 2 17 2 4 2 INSTALLING THE DOOR eee red tortue etes 2 17 2 4 3 INSTALLING THE FRONT DISPLAY CONTROL 2 18 2 4 4 INSTALLING THE PLEXIGLAS COVER eese essen essen 2 18 2 4 5 INSTALLING THE TANDON DRIVE ASSEMBLY ee 2 19 2 4 6 INSTALLING THE ANALOG 2 19 2 4 7 INSTALLING THE FRONT PANEL ASSEMBLY
28. HALT pin for a quick non halt then halt condition If the Z80A halts when it is powered on then something besides the self test probably caused the halt condition The chances of the self test detecting a defective Z80A are extremely unlikely since the Z80A must be operational to some extent for the tests to run at all About all a self test can do is check the registers similar to a quick RAM test A Z80A could still function with one or more bad registers but it would make a mess out or any data it manipulated 3 4 2 ROM Checksum Test This test computes a 16 bit checksum of the controlling ROM EPROM and compares that number to the contents of the last two bytes of the ROM image This test provides a 65535 out of 65536 chance of detecting any bad bits in the ROM image If the ROM image is bad in any areas which the Z80A uses for the tests in section 3 4 1 the 780A will probably get lost before the drive ever gets this far However assuming that the internal diagnostics do get this far and this test fails an error code HB will come up on the drive s LED display Section 3 Page 3 9 GT Field Service Manual 3 4 3 C1 H Quick RAM Test The WART board contains a 6116 2K SRAM chip which is used for internal operations and to store any data that is transmitted or received over the serial bus from the Atari computer This test checks that RAM chip by filling the entire RAM with a 55AAH checkerboard pattern and
29. Index Mark Section 4 Page 4 3 TWO GT Field Service Manual The ADDRESS MARK speed check works on any Atari compatible disk drive The only restriction is that the drive must be configured for the same density as the diskette you are trying to read This method works in the following fashion First it positions the head to track zero sector one When the drive finds this mark it tries to read the mark 100 times The system clock in the Atari computer is polled before and after the reading process to derive the total elapsed time for the reading The average speed of the diskette rotation is then calculated for the 100 reads and the average RPM is displayed on your monitor screen This measurement is accurate to about two tenths of an RPM Although it would have been possible to use a sample smaller than 100 reads the accuracy falls way off when you go as low as 50 reads Press the ESC key to exit this routine lf you press the ESC during a read process the routine will complete the current cycle of 100 reads before exiting The INDEX MARK speed check will work only on the INDUS GT Atari disk drive Density configuration will not affect this speed check This routine looks at the timing hole which is standard to all soft sectored diskettes It counts two revolutions of the diskette The first time around the routine finds the timing hole and sets the system clock on the WART board The second reading is made one revolution later and
30. RATION commend This command will cause the drive to change to the specified density regardless of any other factors The new density mode will remain in effect until the drive is powered OFF the disk is changed again or until a new SET CUNFIGURATION commend is received There is one more way to change the density configuration Holding down the DRIVE TYPE switch on the front display control panel and then pressing the TRACK switch will cause the drive to switch from the current density to the next density in the following sequence SINGLE XA to DOUBLE Xb to DUAL XC to SINGLE XA Section 1 Page 1 8 GT Field Service Manual This manual switching method will shift the density mode once each time the TRACK switch is pressed The data inside parentheses will be displayed in the alphanumeric LED on the front panel The X refers to the drive number and the identify which density mode is currently selected a lower case b is used Instead of the upper case to avoid confusion with the numeric value 8 Whenever the density mode is changed in this way the disk _ change flag is also cleared This permits you to insert a disk which sets the disk change flag and then manually select A different density mode which will clear the disk change flag Note that the manual selection of s density mode must be made AFTER a disk is inserted otherwise the drive will re select the density mode in response to the dis
31. Replace any broken wires on the Analog board STEP 5 If the problem persists replace the Analog board STEP 6 Itthis does not correct the problem then either the photo receiver or the LED transmitter is bad and the TANDON assembly will have to be replaced 6 2 5 Radial Track Alignment and Adjustment The Radial Track Alignment procedure locates the read write head at the proper radial distance on the hub centerline ensuring the track location is accurate Adjustment is necessary only after servicing or if diskette interchange problems are suspected NOTE The alignment diskette and drive must be allowed to stabilize at room temperature for one hour before checks and adjustments are performed RADIAL TRACK ALIGNMENT CHECK NOTE The Radial Track Alignment Check can only be performed with an oscilloscope STEP 1 Set up the oscilloscope Channel Test on the Analog Board Channel B Test Point 3 on the Analog Board Ground Test Point 2 Read Differentially A plus B B inverted Time Base 20 milliseconds per division External Trigger Pin 4 of connector J12 Board ID J8 positive edge Adjust amplitude for at least four divisions on the oscilloscope AC coupled Section 6 Page 6 6 GT Field Service Manual STEP 2 Apply power to the drive NOTE The Track 16 radius is 1 9167 inches from the center of the hub Other track locations are computed based upon 48 TPI STEP 3 Boot up GT DOC in drive 1 see se
32. able into the drive and bend one or more of the pins in the connector You can try to simply straighten the bent pins using a smell set of needle nose pliers but the damage may be so bad that you will have to replace the entire connector This is a problem you should identity when you perform your initial visual inspection of the drive Section 3 Page 3 5 1 Field Service Manual The next most likely connector problem area is with the DIPswitch in the rear of the drive We realize that this is not exactly what you would call a connector but it seems appropriate to discuss it at this point anyway The switch is mechanically attached to the WART board by nothing more than the leads coming out of the package If the user has been changing the switch settings a lot then it is possible to break those rather fragile solder connections Usually the only clue to this is that the drive will refuse to configure to another drive number The remaining connector and wire problems are likely to occur only if the drive has been opened You will have to be careful not to contribute to the problem while servicing the drive The most likely break occurs at the Junction of the 20 pin bus cable on the WART board It is difficult not to flex this flat cable some when you are working on the drive The result is that some of the wires in the cable will break off right at the surface of the WART board This can result in an unpredictable collection of probl
33. act that A was loaded with OFFH will be ignored 5 Theaccumulator A is cleared to 00H and another NOP is executed to give time for any stray IRQs to be trapped 6 The IRQs are disabled DI and A is tested to see if an IRQ occurred The test fails if one did 7 The CMD line is low and then back to high via the CLOCKIN line to cause an IRQ to be latched by the circuitry 8 The IRQs are re enabled and a is performed to give IRQ a chance to 9 The IRQs are again disabled and A is checked to see if an IRQ did indeed occur If one does not occur the test fails If any of the tests in this sequence fail the drive will display H5 in the LED window and the drive will Halt If this test fails try replacing the WART board Section 3 Page 3 14 GT Field Service Manual 3 5 3 C6 H6 Extended RAM Test This test the last one in the series of internal diagnostics executes a time consuming test on the drives static 6116 2K SRAM Since the test is a long one the LED display will alternate between and until the test is complete If a failure occurs the LED display on the drive s front panel will change to H5 and the drive will Halt The extended RAM test is performed in the following sequence 1 2 The entire 2K SRAM is cleared to 00 The least significant bit bit 0 of the first byte 01H of RAM address 0000H is set This byte is the first test byte All
34. ady to begin STEP 8 Using a fiat blade screwdriver between the chassis camming bar and the stepper motor rotate the stepper motor STEP 9 Continue rotating the stepper motor back and forth locating the left and right extremes of where the drive stops reading the disk STEP 10 Adjust the stepper motor so that it is positioned in the center of the two extremes STEP 11 Tighten the stepper motor retaining screws STEP 12 Verify the Alignment by rerunning the Check Disk option on the whole disk then run the write Data option on the same disk STEP 13 If either check does not verify then readjust the stepper motor until it does verify STEP 14 Reformat the test disk on the known good drive STEP 15 Re verify the alignment by running the Check Disk and write Data options Section 6 Page 6 11 GT Field Service Manual 6 2 6 Azimuth Check Azimuth Checks the READ Write head s relative angle to the centerline of the diskette The Dymek Model DK 501 05 contains the azimuth bursts on Track 34 The head s azimuth is not adjustable If the head fails the azimuth check the head carriage assembly is defective Because of the INDUS repair policy the TANDDN mechanism must be replaced STEP 1 Set up the oscilloscope Channel A Test Point 1 on the Analog Board Channel E Test Point 3 on the Analog Board Ground Test Point 2 on IDE Analog Board Read Differentially A plus B B inverted Time Base 0 5 millisecond pe
35. ber one position a means of telling the DOS what density mode they are in even if no disk is installed Also the disk change flag an internal parameter monitored by the drive is set to cause automatic disk density analysis to be performed prior to the processing of the first I O command received over the serial bus At the end ofthe power up initialization tests the drive attempts to read a disk in both single and double density whether a disk is installed or not If the read is successful in single density then the drive is set to single density lf the read is successful in double density then the sector size is examined A sector length of 256 bytes indicates that the drive is to operate in double density mode A sector length of 128 bytes tells the drive that it should go into the dual density mode If the drive is not able to read the disk due possibly to the absence of a disk then the density mode is determined by the setting on the back panel DIP switch Section 1 Page 1 7 GT Field Service Manual When a disk is inserted into the drive a large portion of un notched disk passes through the write protect sensor before the disk is inserted far enough to align the write protect notch with the sensor This causes the drive to go from a write enabled state due to the absence of a disk to a write protected state as the disk is first being inserted into the drive This rising edge of the write protect is latched by the ha
36. by Atari inc Such computers include but are not limited to the following models 400 800 600XL 800XL 1200XL 65XE 130XE and XEGS The INDUS GT disk drive serves as a device for data storage and data retrieval The data may either random access or sequential in nature The specific data structure must be defined by the user s application program Section 1 Page 1 1 GT Field Service Manual FIGURE 1 1 Photograph of an INDUS GT Disk Drive Section 1 Page 1 2 GT Field Service Manual 1 3 PHYSICAL DESCRIPTION A representative INDUS GT disk drive is pictured in Figure 1 1 The drive is s low profile unit black in color with a horizontally mounted TANDON TM50 1 half height 5 25 inch drive mechanism The drive has a smoke colored plexiglas dust cover that at the touch of a front mounted button automatically slides up revealing the disk access slot and the activity display control panel The back of the drive contains two standard 13 pin MOLEX plugs for interfacing to the computer and any other daisy chained devices The back panel also contains the primary power connector and power ON OFF switch for the unit as well as a four pole DIPswitch Figures 1 2 and 1 3 show two levels of an exploded view of the disk drive These drawings are accurate to scale and illustrate the general way that the drive is put together We will be describing each of the assemblies and how you might go about removing or re installing t
37. ction 5 6 STEP 4 Selectthe drive number of the defective drive STEP 5 Selectthe Position Head from the menu STEP 6 Selectthe option to position head to one track STEP 7 Type 16 in response to the Track number STEP 8 Insert a certified alignment diskette Dymek Model DK 501 05 into the drive STEP 9 Adjust the oscilloscope to observe a Cats Eye pattern see Figure 6 2 STEP 10 Verify the smaller of the two Cats Eye patterns is notless than 75 per cent in amplitude of the larger other one NOTE The 75 per cent figure is for use with an alignment verified against a standard alignment diskette STEP 11 Using GT DOC position the head to Track 0 then position it back to Track 16 STEP 12 Verify the Cats Eye pattern 75 per cent STEP 13 If all the checks verify the radial track alignment is acceptable STEP 14 If any check does not verify the stepper motor must be adjusted Section 6 Page 6 7 WQWS5 tT Field Service Manual Figure 6 2 CATS Eye Patterns W Equal amplitude on track 16 Left 70 of right slightly off track toward 15 Right 70 of left slightly off track toward 17 107635 Figure 1 No Head Radial Alignment Necessary Section 6 Page 6 8 tT Field Service Manual RADIAL TRACK ALIGNMENT ADJUSTMENT There are two methods of adjusting the radial track alignment The first and most accurate involves the use of an oscilloscope The sec
38. cular Failure to follow these simple guidelines can result in destruction of sensitive electronic devices and possibly even severe electrical shock for the technician Since these guidelines need special emphasis we will itemize them The special cautionary notes are NOTEI REMOVE THE PRIMARY POWER CONNECTOR FROM THE REAR OF THE DRIVE BEFORE ATTEMPTING ANY ASSEMBLY OR DISASSEMBLY 2 TURN THE DRIVE S POWER SWITCH TO THE OFF POSITION BEFORE PLUGGING IN THE POWER CONNECTOR NOTE 3 MAKE OR BREAK ALL ELECTRICAL CONNECTIONS BEFORE APPLYING ANY POWER TO THE CIRCUITS NOTE 4 PAY CAREFUL ATTENTION TO THE POLARITY OF ANY CONNECTOR BEFORE REMOVING IT ALWAYS USE THE PROPER POLARITY WHEN RE CONNECTING ANY CONNECTOR PAY SPECIAL ATTENTION TO THE 20 PIN BUS CONNECTOR ON THE ANALOG BOARD NOTE 5 PAY CAREFUL ATTENTION TO THE ORIENTATION OF PIN 1 ON ANY IC BEFORE YOU INSTALL IT EACH BOARD HAS A SPECIAL STENCIL ON IT FOR EACH IC INDICATING WHICH WAY THE IC SHOULD BE INSTALLED NOTE 6 MANY OF THE IC S CAN BE DAMAGED BY STATIC DISCHARGES USE PROPERLY GROUNDED TOOLS AND WORKING SURFACES WHEN HANDLING EITHER THE IC S OR THE BOARDS THEY ARE MOUNTED ON Section 2 Page 2 4 GT Field Service Manual 2 3 DISASSEMBLY INSTRUCTIONS For convenience we will assume that any disk drive brought to you for repair will be in an assembled state we will therefore discuss the disassembly of a disk drive first 2 3 1 Removing the Rea
39. d torque them down This task will be easier if you don t tighten the screws until after you have gotten all four screws started The next step is to re connect the 20 pin bus connector to the analog board and the three 4 pin connectors to the WART board You should also make sure that JO 1 and J3 are still properly connected to the analog board 2 4 6 Installing the Analog Board The first step to installing the analog board is to slip the board into position on the top ofthe TANDON drive mechanism One edge of the board fits snugly into slots cut in the drive mechanism Insert the two retaining screws and tighten them down Next plug the three small connectors JO J1 and J3 into their respective places on the board See section 2 3 4 if you have any questions about which connector goes where Finally re install the 20 pin bus connector 2 4 7 Installing the Front Panel Assembly If you have not previously re installed the two 12 pin ribbon cables then go back and remove the TANDON drive mechanism so you can plug the two cables into their positions on the WART board With the connectors plugged in position the front panel assembly so the screw hole on each side lines up with one of the flanges which are on the outside of the chassis Insert the holding screws and tighten them down Next use a small Jeweler s screwdriver or a spring tool to install the small spring on the backside of the assembly Finally slip the loose ends of the hyd
40. drive goes into a density select routine that we will cover in the next section 1 4 2 Multiple Density Operation The drive is designed to work in any o three density modes single dual or double density You will normally need to have a disk operating system DOS that is configured for the mode of operation that you desire Most of the DOS currently available for the Atari operate in only single density mode However several DOS now on the market support double density as well As of this writing there are only two DOS that support the dual or I050 density There are significant differences in the three density modes The original single density configuration consists of 40 tracks with 18 sectors on each track and 128 bytes per sector This mode gives you maximum data storage of 92 160 bytes in a non DOS environment If you need to use the disk via a DOS as most users do then you will have only about 88K bytes of storage space available Section 1 Page 1 6 GT Field Service Manual The so called dual density is similar to the single density configuration except that each track has 25 sectors instead of 18 This yields a theoretical maximum storage capacity of about 133K bytes but once you take into account the usual overhead needed for operating under a DOS environment you end up with only 128K for actual storage This is still an increase of roughly 45 per cent over normal single density hence the occasional use of
41. e 4 7 GT Field Service Manual 4 10 TRACK ZERO ADJUSTMENT This routine is used to realign the track zero sensor in the drive When you run this test the screen display should say Sensor is okay for a properly adjusted drive lf this is the case then no further steps need be taken However if the screen says to move the head in or to move the head out then the drive will need to be disassembled so you can adjust the track zero sensor See section 6 for adjustment procedures 4 11 FORMAT DISKETTE This routine performs a vanilla format on a diskette in any of the three INDUS GT operating modes After the format any errors will be displayed on the monitor screen The format that this routine does is vanilla This means that the format process makes two passes one to lay down a new format and a second pass to verify the new format Normally a DOS will perform these same two passes and then write special DOS related information to the diskette This routine does not perform that last step since there is no way of knowing for sure which DOS you may want to operate under This means boot UTOC or directory sector data is not written to the disk If F9 errors occur persistently then verify that the write protect switch is OFF Any other errors that occur may be the result of a bad diskette Try to format another diskette If errors still occur then try to format the same diskette on another machine If the diskette formats pro
42. e or two small 2 pin connectors in the same bundle of wires Ignore those connectors See Figures 2 4 and 2 5 for exploded views of the TANDON drive mechanism 2 3 6 Removing the Plexiglas Cover This step is needed only if you must replace the dust cover in the front panel assembly What you should have at this stage is a main chassis with the WART board mounted in the bottom of it and a front panel assembly that is only attached by two 12 pin sections of ribbon cable Section 2 Page 2 9 WQWS5 tT Field Service Manual FIGURE 2 4 Exploded View of INDUS GT Disk Drive INDUS GT ATARI MODEL Section 2 Page 2 10 Field Service Manual YS GT FIGURE 2 5 Exploded View of TANDON Drive Mechanism DPL view Page 2 11 Section 2 GT Field Service Manual Take a close look at the ribbon cables Older drives have bulky plastic connectors attaching the cables to the WART board of the later model drives have slim line ribbon connectors When you are ordering replacement parts be sure you specify which type of connector is needed Okay gently disconnect the ribbon cables connectors 10 and J11 from the WART board The front panel assembly should now be totally disconnected from the rest of the drive If you look at the top inside portion of this assembly you will see two small screws which are holding a pair of dowel pins in place These pins are the hinges that the dust cover moves on Loosen these
43. e the small spring you will find attached to the left side of the front panel Place this spring in your holding area Next find the small hydraulic damper on the opposite side of the drive It looks like a miniature shock absorber Slide the end closest to you off of its mounting post DO NOT try to remove the entire front panel at this time If you look at the exploded view drawings see Figures 2 1 and 2 2 ofthe drive you will be able to see that the front panel assembly is still attached to the main assembly by two small ribbon cables This is as tar as you can go in removing the front panel assembly until the TANDON mechanism has been removed Proceed to the next step now 2 3 4 Removing the Top Analog Circuit Board This step is necessary only if you are planning on shipping the analog board back to INDUS for a replacement of your repairs except actually replacing this board can be accomplished without removing the analog board from the TANDON drive mechanism The analog board is held in place by two small screws and three interlocking slots tabs Once you have removed the two screws with the Phillips screwdriver gently wiggle the board from side to side to disengage the tabs from their slots The board should come free easily Once you have the board free you will need to unhook the four connectors that are attached to the board see Figure 2 3 Section 2 Page 2 6 Field Service Manual YS GT FXGURE 2 3 Parts Layout of
44. eading back data Just written to the diskette CLOCKIN bus line control changed to DATAOUT This modification gives the drive the ability to transmit data directly to other devices attached to the data bus The original ability to control the CLOCKIN line was a left over from an earlier design approach to implementing the SYNCHROMESH high speed mode EPROM CODE optimized for size When a need came up for some additional functions see below in the EPROM the code was re written to take up less space on the chip All functions supported by the earlier versions are still supported but with more efficient code Section 4 Page 4 10 GT Field Service Manual Immediate Diskette Analysis The current version of the drive control EPROM supports a new front panel function Holding down the TRACK button and then pressing the DRIVE TYPE button will command the drive to do an immediate diskette analysis In response to this button sequence the drive will analyze the diskette change the drive s density mode accordingly and switch the LED display to DRIVE TYPE Note this can cause strange results if you invoke this command sequence while the computer is sending configuration commands to the drive Auto Boot Feature The current EPROM version supports a manual auto booting of the drive s on board Z80A microprocessor You can invoke this function by holding down the DRIVE TYPE button and then pressing the ERROR button The drive will
45. ems we can suggest here is for you to be aware of the potential for a problem with this cable and make sure you carefully inspect it before you reassemble the drive or replace a good board that Just appears to be bad The second most common problem is with the wires going into connectors J1 and J3 on the analog board These wires are easy to break off when you are sliding the main housing on or off of the drive There are a number of possible symptoms that could result from one of these wires breaking One that is fairly common is that the drive motor runs at 700 plus RPM Less frequently you will have a problem with the three connectors 7 J8 and J9 on the WART board The center connector in particular is a problem occasionally This connector runs back to the write protect sensor If the drive motor refuses to turn DPF the write protect sensor may be bad You can check this by snorting the center two pins of the center connector This bypasses the write protect sensor altogether In this condition the only thing that determines the protect status of a diskette is the front panel PROTECT switch Do not leave a drive in this configuration With those two pins shorted the drive s automatic density selection will no longer work Section 3 Page 3 6 GT Field Service Manual 3 3 4 Door Locking Bar There are two potential problems that you might find with the door locking bar The first and most probable one is that the
46. ervice Manual FIGURE 2 8 Removal of the WART Board Section 2 2 16 GT Field Service Manual 2 4 ASSEMBLY INSTRUCTIONS The steps for re assembling an INDUS disk drive are essentially no more than a reversal of the disassembly instructions However we suggest that you read through this section at least once to make sure that you don t overlook some crucial step The instructions will start with the assumption that you have a completely disassembled disk drive 2 4 1 Installing the WART Board Slide the WART board into position in the bottom of the main chassis Align the screw holes with their counter parts on the bottom of the chassis Using a Phillips screwdriver install the four corner screws Don t torque them down until you have all four loosely screwed in Now install the screws that go through the two voltage regulators VR1 and VRZ which you will find near the main power switch 2 4 2 Installing the Door Latch Strangely enough this is actually the most difficult step in re assembling one of these drives First place the small latch spring in its slot on the front panel Now put your finger behind the assembly to hold the spring in place and compress the spring by using the bottom of the center flange on the latch itself Make sure that the beveled part of the latch is toward the bottom of the assembly It may take a little maneuvering to get the latch back in place with the spring pro
47. f the sensor is for the Track 0 stop see Figure 6 7 STEP 3 Moue the sensor to the rear of the drive as far as it will go STEP 4 Run the Track Zero Adjustment option in GT DOC STEP 5 Insert an 810 single density formatted disk STEP 6 Slide the Track 0 sensor toward the spindle very slowly until the screen displays Sensor is ok STEP 7 Retighten the screw on the spindle side of the sensor STEP 8 Repeat the Track 0 sensor check 6 2 8 Track 0 Stop adjustment The Track 0 stop screw should be adjusted after the Radial Track alignment has been performed or when the carriage seeks to a track lower than Track 0 STEP 1 Selectthe Position Head option of GT DOC STEP 2 Position the head at Track 0 STEP 3 Loosen the Number 1 Phillips screw at the rear of the Track 0 sensor see Figure 6 7 STEP 4 Slowly push the Track 0 stop block into the Track 0 sensor until the Track 0 stop hits the head carriage STEP 5 Retract the Track 0 stop 1 32 of an inch Tighten the Track B stop block screw Section 6 Page 6 16 WQWS5 tT Field Service Manual Figure 6 7 Track 6 Stop Block TRACK SENSOR CHASSIS CAMMING BARS TRACK O STOP BLOCK Section 6 Page 6 17 GT Field Service Manual 6 2 9 COMPLIANCE CHECK AND ADJUSTMENT Compliance is the maximized output of the head when the pressure of the felt pad is centered over the read write gap Compliance Check STEP 1 Set up the o
48. fthe problem persists replace the WART Board Section 5 Page 5 7 GT Field Service Manual Chapter 6 REPAIR GUIDELINES 6 1 OVERVIEW OF REPAIR GUIDELINES This section outlines the steps necessary to verify the operation of an INDUS GT disk drive during troubleshooting or after replacing a part or subassembly The checks and adjustments in the order presented will help you to isolate the problem area However if a specific check or adjustment is required you do not necessarily have to perform all of the preceding checks The values and tolerances stated in the checks and adjustments are typical values for working drives If the values you measure are within those tolerances or close to the limits the defective drive s problem is probably due to some other cause Completing the other checks and adjustments may disclose the actual cause of the problem 6 2 THE TANDON DRIVE MECHANISM For convenience we will assume that the drive has been disassembled to the point of having the main housing removed 6 2 1 Visual Inspection Before applying power to the drive or doing any checks or adjustments visually inspect the drive 1 Checkforloose or missing hardware 2 Make sure the front latch opens and closes and the head arm raises when the door is opened 3 Make sure the front panel is securely attached 4 Manually rotate the drive hub It should rotate freely 5 Make sure the circuit boards are securely seated 6
49. g board If Step 1 failed to fix the problem the stepper motor is probably bad Replace the TANDON Mechanism Section 5 Page 5 2 GT Field Service Manual 5 4 DRIVE MOTOR PROBLEMS 5 4 1 Drive Motor Won t Rotate 1 Short pin 10 of connector J2 to ground 2 The drive motor should be rotating If the drive motor does not rotate the drive motor probably is bad Replace the TANDON Mechanism 3 Ifthe drive motor rotates then replace the LM2917 comparator 5 4 2 Drive Speed Unstable 1 Check for bad spindle bearings by removing the drive belt and slowly rotating the spindle pulley manually If the spindle pulley rotates erratically the spindle bearings are bad Replace the TANDON Mechanism 2 Ifspindle speed drifts slowly replace the Analog Board 5 4 3 Drive Speed Stable But Out Of Tolerance 1 See Section 6 3 on motor speed adjustment 5 5 READ ERRORS Before you make any adjustments first verify that any dirt or oils do not contaminate the head as that may be the cause of the problem 5 5 1 READ ERRORS All Tracks 1 Check radial track alignment see Section 6 2 5 If the alignment is bad realign the drive Section 5 Page 5 3 TWO GT Field Service Manual 2 Check compliance see section 6 2 9 If compliance is bad replace the Felt Pad assembly and or clean head 3 Replace the MC3470A read amplifier on the Analog Board 4 Ifyou still get no read signals from the drive replace the Analog B
50. handle on the front of the bar may come off 14 it has come off or been broken simply replace the handle Figure 3 2 shows what the bar assembly looks like in an exploded view There is a stud screwed into the shaft et a right angle end the handle is installed with a simple press fit The second possible problem is more serious and probably will require you to replace the entire TANDON drive mechanism The back end of the locking bar has a rather peculiar looking cam attached to it by a smell dowel pin If that dowel pin breaks or falls out the drive spindle will not be able to engage the diskette Since the only replaceable sub assembly in the TANDON mechanism is the entire TANDON mechanism you must replace the entire drive assembly 3 3 5 Drive Belt The drive belt is not on the approved replacement list It this belt breaks you will have to replace the entire TANDON drive mechanism The primary symptom of a broken drive belt is that the diskette drive spindle will rotate manually but not when you power up the drive You will have to remove the TANDON mechanism and visually inspect the bottom of itto find out if the belt is really broken 3 3 6 Read Write Head Guide Rails The read write heed slides back and forth on a pair of metal guide rails If these rails are not lubricated properly the drive may not function normally Specifically the drive may have trouble reading or writing random sectors on a diskette A dirty read write head co
51. hem later in this manual Right now all you need to do is get a general picture in your mind of exactly what you will be working with Internally the disk drive consists of several major sub assemblies There is of course the TM50 1 TANDON single sided floppy disk drive mechanism and the associated wiring and connectors The supporting electronics are laid out on two printed circuit boards PCB s The PCB that you see on top ofthe drive mechanism is the analog board You will find such things as the read write and motor control circuits on this board If you remove this board and the TANDON drive mechanism you will see a board laying flat on the bottom of the drive housing This board is the digital board that contains the brains of the disk drive The digital board will be referred to throughout this manual as the WART board The name is derived from the original project title for the development of the disk drive WART is an acronym for Wonderful Atari Rotating Thing The WART board contains the Z80 A CPU it s controlling ROM EPROM a 2K RAM buffer and a Western Digital 2797 floppy disk controller FDC among other things In later sections we will discuss each of the major components on both of the boards Section 1 Page 1 3 WQWS5 tT Field Service Manual FIGURE 1 2 Exploded View of INDUS GT Disk Drive INDUS GT ATARI MODEL Exploded View Section 1 Page 1 4 Field Service Manual YS GT FIGURE 1 3 Exploded V
52. here between 12 2 and 13 0 volts DC You can verify this by using any common voltmeter Note that the output is DC not AC like the Atari power transformers It is possible that someone may have accidentally attached one of the AC Atari supplies to the INDUS drive The result would be a non operating INDUS disk drive but there should be no actual damage to the INDUS drive electronics First check the power supply that came with the drive and verify that it is a standard INDUS unit Next attach your voltmeter to the output connector of the power supply and plug the power supply into a normal 120 VAC wall socket Verify that the output of the power transformer is between 12 2 and 13 0 volts DC If the power supply checks out okay then unplug it from the wall socket and disconnect the voltmeter Section 3 Page 3 2 GT Field Service Manual 3 2 2 Power Input Connector The INDUS input power connector is a simple device and is unlikely to cause you any problems but it is possible that it may be damaged by excessive physical abuse About the only thing that could go wrong is one of the three solder connections with the WART board might get cracked or broken You will have to almost completely disassemble the drive to check this since you will have to actually remove the WART board The older models or the INDUS drive have a power connector that is slightly too large in diameter and slightly too short in length depth for the standard
53. iew of the TANDON Drive Assembly Page 1 5 Section 1 GT Field Service Manual 1 4 FUNCTIONAL DESCRIPTION The INDUS GT Atari disk drive is a 5 1 4 inch floppy Disk drive that will interface with any of the various Atari 8 bit home computers The drive is a multi density drive and is compatible with virtually any DOS currently available for the Atari This section will describe some of the major features of the drive and give you a better understanding of how the drive is supposed to function 1 4 1 Power Up Self Tests When you first apply power to an INDUS GT disk drive the on board Z80 computer runs a series of tests on the drive to determine if all of its major subsystems are in working order To minimize the amount of time such testing will take only four tests are normally made at this time As each of these tests is running the alphanumeric display on the activity control panel will flash through the values C1 and C3 If an error occurs any of these tests H will replace and the drive will stop testing at that point We will be covering all of these tests and the optional series of extended tests later in this manual so we will not go into much detail here Suffice it to say at this time that the drive runs a test on the drive s ROM EPROM the on board 2K RAM the Z80 index registers and the western Digital floppy disk controller Once the drive has passed all of these internal tests the
54. k change 1 4 3 Input amp Output Input and output of date is accomplished through the standard 13 pin MOLEX plug that is found on all devices that connect to the Atari computer s serial 1 0 port Only one such connector is required to interface to the computer but any other peripheral devices such as a second disk drive must be daisy chained to the system This daisy chaining is accomplished by using the second 13 pin I 0 plug on the disk drive 1 4 4 Activity Control Panel Displays The drive has several LED displays on the front control panel that supply various types of information There are the usual POWER and BUSY indicators that let you know when the unit is powered up and when the I O data bus is being accessed There is also a PROTECT indicator that tells you whether or not the drive is allowed to write to the disk that is currently inserted The most important LED display on the front panel is a two digit alpha numeric display that can provide you with a variety of information This display can tell you the current density drive number track being accessed and I D error status Three push button switches on the display control panel determine which of the display modes will be active The only exception to this is that the error code display will over ride all other modes when an error occurs Section 1 Page 1 9 GT Field Service Manual 1 5 REPAIR REPLACEMENT POLICY This manual is intended for use b
55. ler a copyrighted product of Monarch Data Systems Cochituate MA 01778 We suggest that you run this program on a computer system that has a known good drive for drive number one It does not matter whether the system drive is an INDUS GT or not for the purpose of running this program Attach the defective drive to the system as drive number two The master diskette containing the GT DOC program comes with the OSS disk operating system on a standard single density diskette lf you normally run your system in double or dual density simply transfer the file GTDDC COM over to a diskette formatted in the desired density The program is independent of DOS in most of its functions Exceptions to this rule will be noted in the write up on the appropriate commands Although it is possible that some ofthe routines in the GT DOC program may work on a non INDUS drive we do not support any operations on other types of drives Before you go any further turn ON the drive to be tested If it passes the initial internal diagnostics then GT DOC will function properly on the drive Section 4 Page 4 1 GT Field Service Manual To run GT DOC boot your computer system and perform a binary load of the file GTDOC COM The master program diskette contains the OSS DOS and the OSS DOS menu If you are booting from this diskette the following steps will get you going 1 Turn drive number one ON 2 Insertthe GT DOC master diskette label side u
56. m When it comes to replacing any IC pay close attention to the pin I mark on the IC as well as the pin 1 mark on the IC socket see Figure 6 10 Pay close attention when inserting an IC so that every pin is correctly lined up with the corresponding hole in the IC socket The IC should be firmly seated in its socket Section 6 Page 6 23 1 Field Service Manual Figure 6 18 Pin 1 Location On ICs And IC Sockets 1 1 Section 6 Page 6 24 GT Field Service Manual 6 5 REPLACING THE CIRCUIT BOARDS When replacing either the WART or Analog Board take care to avoid causing damage to them when removing a defective circuit board use properly grounded tools and working surfaces This is necessary to avoid damage to any ofthe static sensitive IC s When installing either a new WART or Analog board the same care applies to them as did to the defective circuit boards A new circuit board can he easily damaged ii care is not taken to insure its safety When shipping the circuit boards back to INDUS SYSTEMS for replacement care must also be taken to ensure their safety The circuit boards should not be allowed to touch each other during transport Also the package should be labeled with CAUTION static sensitive material enclosed 6 6 REPLACING THE LED PANEL STEP 1 Refer to Section 2 3 7 regarding the removal of the LED panel STEP 2 If all segments of one or both numeric readouts are out replace the LED
57. more than one half of an RPM on consecutive reads is not normal and further service may be required 4 5 DRIVE CONFIGURATION INQUIRY This routine polls the drive for its current density configuration and allows you to verify that all three densities single dual and double are functioning Start by pressing the DRIVE TYPE button on the front panel of the drive to cause the drive to display its current density setting Next press either A B or C on the computer keyboard to select another density The computer will send an inquiry code along with configuration instructions to the drive The results are displayed on the screen as follows Humber of Tracks 48 Step Rate 26 mz Sectors per Track 18 Density single Sector Sire 128 Drive Present The Number of Tracks should show 40 in all cases for an Atari disk drive regardless of the brand name The Step Rate for all INDUS GT Atari disk drives is 20 ms The Sectors per Track number will be one of two values For single and double density this number should be 18 Dual density uses 26 sectors per track Section 4 Page 4 5 GT Field Service Manual The Density figure shows what the current density setting is for the drive single double or dual You can change the density setting by pressing A B or C on the computer keyboard This function is independent of whether a diskette is in the drive or not The Sector Size shown in the display should be 128 f
58. n nnn nnn itn ii e i e i t i i 6 21 6 4 REPLACING INTEGRATED CIRCUITS 6 23 6 5 REPLACING THE CIRCUIT BOARDS eese netten tnter tertii tiri t tin 6 25 6 6 REPLACING THE LED PANEL eee innen nnn nennen niin iiti iei te i e 6 25 6 7 REPLACING CONNECTORS sessi inminente ini ao 6 25 CHAPTER7 SCHEMATICS amp DRAWINGS eese seen tinet inne inne e t ni 7 1 UP n P 8 1 8 1 Page iii GT Field Service Manual Chapter 1 GENERAL DESCRIPTION 1 1 Introduction This document provides all of the information a field service technician might need to troubleshoot end repair one of the Atari compatible disk drives manufactured by INDUS Systems Inc All references in this manual ere applicable only to the Atari compatible model This document consists of the following sections SECTION 1 0 General Description SECTION 2 0 Disassembly amp Assembly SECTION 3 0 Diagnosing A Problem SECTION 4 0 Diagnosis with GTDOC SECTION 5 0 Troubleshooting Guidelines SECTION 6 0 Repair Guidelines SECTION 7 0 Schematics amp Drawings SECTION 8 0 Parts Lists plus various appendices 1 2 PURPOSE OF EQUIPMENT The INDUS GT Atari compatible disk drive is a compact memory device designed for use with any of the personal computers produced
59. normally be installed Make sure that the two retaining screws are well clear of the place where the dowels need to go Now push the dowels through the hinge holes in the cover and correct the cover s position as much as you can Spread a little quick drying cement such as airplane glue on the outside end of each dowel pin being very careful not to let any glue get on the plexiglas cover If you get any glue in a hinge hole IMMEDIATELY remove the dowel pin and clear the hinge hole If everything is going okay so far then tighten the retaining screws until they hold the pins in place Yes the screws are supposed to be in contact with the wet glue Double check the proper positioning of the dust cover and then let the glue dry If you positioned everything just right the cover should be able to easily clear the top edge of the front panel assembly Unfortunately the only way to accurately check this out is by raising the dust cover when it is installed on the main chassis Section 2 Page 2 18 GT Field Service Manual 2 4 5 Installing the TANDON Drive Assembly First take the front panel assembly and plug the two ribbon cables back into their appropriate places J10 and J11 on the WART board Next slide the TANDON drive assembly into the top cavity of the main chassis and line up the holes in the chassis with the screw holes in the sides of the TANDON drive mechanism Now insert the holding screws into their respective holes an
60. o react The FDC status register is checked to see if the index was recognized The test fails if it was not recognized The FDC index pulse line is deactivated The Z80A delays for slightly more than 20 microseconds to give the FDC time to react The FDC status register is checked to see if the removal of the index was recognized The test fails if it was not recognized If any of these tests fail the drive will show H3 in the LED display and H alt Section 3 Page 3 11 GT Field Service Manual 3 5 LEVEL TWO INTERNAL DIAGNOSTICS Only a service technician normally uses the LEVEL TWO internal diagnostic tests since a specially configured MOLEX connector diagnostic plug are required to run the tests These tests perform a more extended series of tests on the disk drive When LEVEL TWO testing is initiated the drive first performs all of the LEVEL ONE tests Then the drive performs the following series of tests 1 Peripheral bus interface test 2 Interrupt circuitry test 3 Extended SRAM static RAM test This section will first explain how the MOLEX connector must be configured and how to invoke the LEVEL TWO internal diagnostics Then we will discuss each of those tests in detail The MOLEX Test Connector The MOLEX connector is the standard 13 pin serial bus connector used to interface the disk drive to an Atari computer For this test you will need one of these connectors without a cable attached and with
61. oard 5 Ifyou still get no read signals from the drive the head carriage assembly probably is bad Replace the TANDON Mechanism 5 5 2 READ ERRORS Random Tracks 1 Clean the read write head 2 Ifread errors are still present test for unstable drive speed using the motor speed check option of GT DOC 3 Ifthe drive speed is unstable the drive motor probably is bad Replace the TANDON Mechanism 4 Replace the MC3470A read amplifier on the Analog Board lf the problem is still present replace the Analog Board 5 Ifthe problem is still present the head carriage assembly probably is bad Replace the TANDON Mechanism 5 5 3 READ ERRORS Inside Tracks 1 Check compliance see section 6 2 9 If compliance is bad replace the felt pad and or clean the head 2 Replace the MC3470A read amplifier on the Analog Board If the Problem is still present the head carriage assembly probably is bad Replace the TANDON Mechanism Section 5 Page 5 4 GT Field Service Manual 5 5 4 Cannot Read Prewritten Data Can Read Self written Data 1 Check radial track alignment see section 6 2 5 2 Check for correct drive speed using GT DOC 5 5 5 Cannot Read Disks written By This Drive Disks Can Be Read By Other Drives 1 Replace the MC3478A read amplifier If problem is still present replace the Analog Board 2 If problem is still present the head carriage assembly probably is bad Replace the TANDON Mechanism
62. ofthe other bytes in the entire RAM are tested bit by bit to see if any other bits have toggled on If any bit other than the proper one is set the test fails The original test byte is re examined to verify that the test bit is still set and no other bits are set If the byte is set incorrectly the test fails The original test byte is cleared to 00H The next byte RAM address 0001H is selected as the new test byte and the test sequence is repeated This loop is repeated until every byte in the RAM has had a chance at being a test byte The test bit the one being turned on is changed to bit 1 and the entire test series is repeated from step number two This exterior loop is repeated until every bit in every byte has had a chance to be the test bit If this test fails replace the SRAM chip 6116 at U13 on the WART board Section 3 Page 3 15 1 Field Service Manual When the LEVEL TWO Diagnostics are completed When the LEVEL ONE internal diagnostics are successfully completed the drive is initialized for normal operation however when the LEVEL TWO internal diagnostics are successfully completed an E no error is displayed in the LED window and the drive freezes up goes into an infinite loop while it produces a tone over the computer bus audio line The tone is to alert you that the LEVEL TWO test is complete The drive does not initialize for operation following the LEVEL TWO internal diagnostics for two rea
63. ond and less accurate involves using GT DOC in its Check Disk mode Both methods are explained below Radial Track Alignment Adjustment With An Oscilloscope STEP 1 Loosen the two Number 1 Phillips retaining screws on the stepper motor see Figure 6 3 STEP 2 Using a flat blade screwdriver between the chassis camming bar and the stepper motor rotate the stepper motor STEP 3 Observe the Cats Eye pattern STEP 4 Adjust until the Cats Eve patterns are equal in amplitude 4 r Equal amplitude on track E E Y 16 a B n1 RB ABBA ARN STEP 5 Tighten the stepper motor retaining screws STEP 6 Recheck the Radial Track Alignment Section 6 Page 6 9 TWO GT Field Service Manual Figure 6 3 Stepper Motor Retaining Screws amp Camming Bars CHASSIS CAMMING BAR RETAINING SCREWS BOTTOM OF DRIVE AE Be ES IESU tcr STEPPER MOTOR RETAINING SCREWS AND CAMMING BARS Section 6 Page 6 10 TWO 1 Field Service Manual Radial Track Alignment Adjustment with GT DOC STEP 1 Boot up GT DOC as outlined in section 4 0 STEP 2 Select the number of the drive to be adjusted STEP 3 Select the Check Disk option on the menu STEP 4 Loosen the two Number 1 Phillips retaining screws on the stepper motor see Figure 6 3 STEP 5 Insert a Known Good Disk STEP 6 Press PETURN in response to the starting sector STEP 7 Press RETURN when re
64. or single or dual density and 256 for double density This number corresponds to the maximum number of bytes that can be stored in a single sector The Drive Present status has a entire bit allocated for it in the status byte received from the drive so it must mean something important Anyway you will probably always see a YES here since if the drive is not present you will get A device error that returns you to the main menu If any of the above displays deviate significantly from what we just described the drive probably has a defective EPROM or a bad I O connection 4 6 DRIVE SELECT This routine selects a new drive for testing You will be prompted to enter a number from one to eight similar to when you first began program execution The same restrictions we described there are still in effect 4 7 EXIT TO DOS This routine does not return to DOS in the manner you are probably used to What actually happens in this case is that a Jump is made to the SYSTEM RESET vector and the computer reboots Because the Jump is a system reboot you will be prompted with a yea or nay question before the program actually executes this command Section 4 Page 4 6 GT Field Service Manual 4 8 FDC TYPE This routine sends a forced interrupt to the floppy disk controller and measures the response time of the FDC Based on this timing the program can tell whether the drive has a WD177X or a WD279X series FDC The result of the poll is
65. or two drives and you attempt to get a directory on drive three an error message will appear The easiest thing to do is configure your DOS diskette for four drives and then you will not have to worry about drive NAK errors The OSS DOS supplied on the GT DOC master diskette has been configured for four drives for you If there are no errors then a standard DOS type directory will be displayed twelve entries at a time You will be prompted to press the RETURN key to progress through the directory if there are more than eleven entries Once the complete directory has been displayed you can exit back to the main menu by pressing the ESC escape key In general the ESC key will be a valid exit from any of the menu functions 4 4 MOTOR SPEED The SPEED of a disk drive motor is normally measured in revolutions per minute RPM There are two ways to measure the apparent RPM of an INDUS GT disk drive The first method consists of disassembling the drive and adjusting the RPM while observing the radial tachometer strobe located on the bottom of the TANDON drive mechanism The other method is to measure the RPM via software while you adjust the speed There are two ways in which software can measure the speed of an INDUS GT disk drive The first method also the most familiar to Atari owners uses what is known as the Address Mark The second method which will be more familiar to IBM and TRS 80 owners uses the timing hole to measure the
66. p 3 Turn the computer ON NOTE Hold down the OPTION key on a 600XL or 800XL 4 Waitforthe DOS menu to appear on the screen 5 Now perform a binary load of GTDOC COM NOTE Do NOT use the Xtended Command menu option 4 2 THE COMMAND MENU The first thing that the program will ask for is the drive number to be tested You may specify any number from 1 to 8 but remember that the computer can address only four drives under normal operation due to hardware limitations in the Atari computer itself Assuming that you are using the recommended two drive set up you should enter the number 2 at this time The GT DOC main menu will then appear on the screen showing you the following options A Disk Directory H Track Zero Adj B Motor Speed I Format Disk C Config Set Inq J LED Test D Drive Select K Drive Status E Exit To Dos L ROM Version F FDC Type M Position Head G Write Data N Check Disk The following sections will describe each of the menu options in some detail and give you a reasonable idea of what kind of diagnostic information you can derive from them Section 4 Page 4 2 GT Field Service Manual 4 3 DISK DIRECTORY NOTE This function is DOS dependent This function tries to read the directory on a standard DOS formatted diskette The directory function will operate in any of the standard density modes provided you have a DOS formatted disk in the specified drive If the DOS is configured f
67. perly then open the drive mechanism and verify that the connectors J7 JS and J9 are all properly seated in the correct positions 4 12 LED TEST This routine lights all of the front panel display LED s You should see an 88 displayed on the drive If any of the LED segments do not light replace the front panel Section 4 Page 4 8 GT Field Service Manual 4 13 DRIVE STATUS This routine displays a dynamic extended status report of the drive After each statement there will be either an ora T The stands for false and the T for true The last statement on the screen displays which track the drive s read write head is on during that particular status check This status test will repeat indefinitely until you exit the routine by pressing the ESC key If the track number displayed on the screen disagrees with the track displayed on the drive then replace the EPROM and rerun this test If FDC DATA or CMD errors appear for more than a few seconds return to the main menu From there repeat the status test This time there should be no errors If there are still errors the problem lies in the EPROM or it is an intermittent problem with the FDC 4 14 ROM VERSION As of this writing there have been three production releases of the INDUS GT Atari disk drive control EPROM 1 00 1 10 1 20 There is also the possibility that a ROM or a PROM will replace the EPROM in the future If the EPROM in the drive you are working
68. perly compressed Once you have done this hold the latch in place with one hand and position the crew cut washer over the hole on the backside The flat section of the washer should be towards the top of the assembly Now comes the hard part while holding the latch in place and without losing the washer insert the holding screw back in its hole and tighten it down Do not tighten the screw too much or the door latch will not function properly You may have to use a magnetized screwdriver to actually be able to accomplish this with only two hands Section 2 Page 2 17 GT Field Service Manual 2 4 3 installing the Front Display Control Board Before installing the display control board make sure that any of the push buttons that may have fallen out are back in place Then position the display control board inside the front panel assembly with the ribbon cables coming out the back of the assembly The small slot that is cut into the side of the board should fit over the screw that holds the door latch in place lf the board does not slide into place easily try loosening the holding screws a little bit Once you have the board positioned in the front panel assembly lightly tighten the two screws until the board is snugly held in place Do not over torque the screws or you may damage the board 2 4 4 Installing the Plexiglas Cover Position the Plexiglas dust cover inside the front panel assembly in approximately the place it will
69. power supply output connector This results in a poor power connection and the plug tends to fall out of the socket it you look at it too hard Unfortunately itis hard to tell the difference between the old and the new connector except in the way the transformers output plug fits into it One general rule of thumb is that all drives that have a version 1 2 ROM or EPROM should have the new power connector Drives with an earlier ROM version probably will have the old connector 3 2 3 Internal Power Elements There are a number of components on the WART board that are associated with the input power These are what we are calling internal power elements None of these components are on the approved replacement list li you trace a power problem down to a defect in the WART board then simply replace the entire board unless the problem is a bad power connector In general terms anytime you trace a problem to the components other than IC s or connectors on a PWA you are supposed to simply replace the board and send the defective board to INDUS for a new one This case is no exception but we suggest that you perform further diagnostics before automatically replacing the WART board Section 3 Page 3 3 GT Field Service Manual 3 3 MECHANICAL PROBLEMS Mechanical problems can sometimes be the easiest ones to spot and the most difficult ones to fix We will address some of the more common mechanical problems in this section If pre
70. r Panel Place the disk drive on your workbench and position the drive so the rear is facing towards you Using a medium sized Phillips screwdriver remove the two screws you see one on each side of the panel Place the screws in a holding area and gently pull the plastic frame off of the rear surface of the drive Do not remove the thin plastic graphics overlay unless it is already damaged You may now proceed to the next step in the disassembly 2 3 2 Removing the Main Housing After completing section 2 3 1 turn the drive upside down and law it flat on your workbench You will see two small screws on each side of the bottom Using a Phillips screwdriver Remove each of these screws and place them in your holding area Now lift the rear of the drive up with the bottom towards you and grab the outside of the housing in both hands Place your thumbs on the rubber set and gently pull the housing up and off of the main disk drive assembly You may now proceed to the next step in the disassembly Section 2 Page 2 5 GT Field Service Manual 2 3 3 Removing the Front Panel Assembly After completing section 2 3 2 set the drive down with the rear of the drive towards you and you will see two small screws holding the front panel assembly to a pair of right angle flanges Using a Phillips screwdriver remove those two screws and place them in your holding area Now using either a spring tool or the Jeweler s screwdriver Gently remov
71. r division External Trigger Pin 4 of connector J12 Board ID J8 positive edge Adjust the amplitude for at least four divisions on the oscilloscope STEP 2 Using GT DOC Position Head position the head to Track 34 STEP 3 Insert a certified alignment diskette Dymek Model DK 501 05 into the drive STEP 4 Verify the head azimuth is no greater than 12 minutes by comparing the four azimuth bursts with those in Figures 6 4 6 5 and 6 6 Section 6 Page 6 12 GT Field Service Manual Figure 6 4 An azimuth Of Exactly Zero Minutes The optimum head azimuth alignment OPTIMUM HEAD AZIMUTH ALIGNMENT Section 6 Page 6 13 GT Field Service Manual Figure 6 5 An Azimuth of Exactly Minus 12 Minutes The lowest allowable azimuth error HEAD AZIMUTH OF ACCEPTABLE LOWER LIMITS Section 6 Page 6 14 GT Field Service Manual Figure 6 6 An Alignment of Exactly Plus 12 Minutes The highest allowable azimuth error HEAD AZIMUTH OF ACCEPTABLE UPPER LIMITS Section 6 Page 6 15 GT Field Service Manual 6 2 7 Track 0 Sensor adjustment The Track 0 sensor circuitry provides a signal that identifies Track 0 to the logic electronics The electronics disable the step out function when Track 0 is reached STEP 1 Loosen the retaining screws on the base of the Track B sensor STEP 2 Retighten the screw on the spindle side o the sensor to provide some friction on it The screw at the rear o
72. raulic door damper over the screw post you will find on the other side of the chassis The log wheels on the damper should be towards the bottom of the drive Section 2 Page 2 19 GT Field Service Manual Chapter 5 DIAGNOSING PROBLEM 3 1 WHAT TO DO FIRST Before you actually try to repair a defective disk drive you should try to get some idea as to what is wrong with it The first thing to do is read the service report if any to see if you can isolate the probable cause of the defect Next you should give the drive a good close visual inspection Note any obvious defects and determine whether they need repair or not Finally before you disassemble the disk drive go through this inspection checklist 1 Inspectthe power and I O connectors Make sure that they are properly installed and that they have no broken pins Also make sure that their mating cables plug in properly 2 Verify that the dust cover lifts smoothly and that the front latch opens and closes easily The head arm should lift when the front latch is open 3 Verify that a diskette can be easily inserted and removed from the drive 4 Takethe main housing off of the drive and make sure that all of the circuit board connectors are properly seated and have no broken wires 5 Checkfor any loose or missing hardware 6 Manually rotate the drive hub It should rotate freely 7 Checkthe circuit boards for any damaged or missing components 8 At
73. rdware and is used by the internal software as a signal that the disk has been changed Whenever such a disk change is detected the drive motor is turned ON without turning ON the BUSY LED to improve the centering of the disk during clamping and the disk change flag is set to indicate that a new disk must be analyzed This flag causes the drive to analyze the new disk as we Just discussed as soon as a new I O command is received from the Atari host computer and prior to actually executing the new command However the software cannot detect the door closing and can therefore only provide you with A fixed amount of motor spin time before it shuts the motor OFF again This creates the requirement that you insert the new disk all the wav in and shut the door all in one smooth action Failure to do this can result in improper centering of the disk during the clamping process The only exception to the automatic disk analysis following a disk change is if a format command has been sent from the computer If a format command has been received from the computer then the drive will not change its current density configuration This permits disks that have already been formatted at one density configuration to be re formatted under a new density configuration This feature is really of interest only to those users who do not have a multi density DOS The last automatic operation which can cause the density configuration to change is receipt of a SET CONFIGU
74. scilloscope Channel A Test Point I on the Analog Board Channel B Test Point 3 on the Analog Board Vertical Amplitude 100 millivolts per division Ground Test Point 2 on the analog Board Read Differentially A and B B inverted Time Ease IB microseconds per division External Trigger Pin 4 of connector JI2 Board ID J8 positive edge STEP 2 Using the Position Head option of GT DOC position the head to Track 32 STEP 3 Insert a certified alignment diskette Dymek Model DK 501 05 into the drive STEP 4 Observe the output waveform voltage STEP 5 With a gram gauge carefully apply fifteen grams pressure to the upper arm NOTE Fifteen grams is about the weight of a quarter STEP 6 If the output shown on the oscilloscope increases by more than ten per cent adjust the compliance Section 6 Page 6 18 GT Field Service Manual Compliance Adjustment Compliance is adjusted by using the same procedure used in the compliance check In addition 1 The spring tension for the pad arm has three positions for the spring end in the lower portion on the head carriage assembly see Figure 6 08 2 While monitoring the oscilloscope change the spring tension position if output amplitude is not affected by different positions of the spring replace it 3 Ifthe pad is worn replace it Section 6 Page 6 19 WQWS5 GT Field Service Manual Figure 6 8 Upper Arm and Compliance Spring FELT PAD COMPLIANCE SPRING
75. sent most of these problems will be glaringly obvious to You during your initial visual inspection of the drive 3 3 1 Dust Cover will Not Open This problem is fairly common and can be caused by a couple oY things The dust cover is hinged on a couple or dowel pins If the cover gets pressed from the top it is possible to knock the dowel pins out of alignment This can result in faulty operation of the dust cover It is also possible that the drive was left in a place such as a car when the environment was hot enough to cause the cover to warp the problem is due only to a misalignment of the dowel pins and then you can correct the problem by physically realigning them 14 the cover itself is damaged then you must replace It In either case you will find instructions for installing a dust cover in section 2 4 4 There are a couple of other possible problems you might run into in this area First the cover will not open properly if the door spring has come off or if the hydraulic damper is malfunctioning You could also have a problem if the door latch is not sliding properly 3 3 2 Missing or Broken Springs There are four or five different springs in an INDUS disk drive They are highlighted in Figure 3 1 Spring number five has little bearing on the operation of the drive but the other four will have a very noticeable effect ii they are broken or missing If a spring is broken or missing replace it Section 3 Page 3 4 TWO GT
76. sons First the special MOLEX shorting connector is still in the drive s I O port Second the LEVEL ONE diagnostics must be run again to properly configure the drive for normal operation If you wish to set the drive up for normal operation turn the drive OFF remove the diagnostic connector and reconnect the standard Atari I O cable Once this is done turn the drive power back ON and the drive will perform its usual LEVEL ONE internal test before it is ready for normal operation NOTE Once the LEVEL TWO internal diagnostics have been completed you can restart the entire test series again by pressing and holding down the TRACK DRIVE TYPE and ERROR buttons Section 3 Page 3 16 GT Field Service Manual Chapter 4 DIAGNOSIS WITH GT DOC 4 1 OVERVIEW OF GT DOC GT DOC is a compiled BASIC program designed to exercise various functions of the INDUS GT Atari disk drive The program assumes that the drive in question has already passed the internal diagnostics we described in section 3 8 The features of this menu driven diagnostic program can be an aid in isolating the possible cause of a problem before you open the drive casing The GT DOC program should run properly on any Atari 400 800 1200XL or 600XL 800XL that has at least 40K of RAM You do not need any special peripherals except for an INDUS GT Atari disk drive A printer is not required The program source code was written in Atari BASIC and compiled using the ABC Compi
77. switch on the drive to OFF STEP 2 Connect the defective drive to the computer system as drive 2 STEP 3 Boot the GT DOC in disk drive 1 This implies that the computer power is ON and that drive number 1 is ON STEP 4 Using the DVM verify that the INDUS GT power supply voltage is between 14 5 and 15 6 VDC when the drive is OFF STEP 5 Apply power to the defective drive STEP 6 With a DVM verify that the power supply voltage is between 12 2 and 13 8 VDC STEP 7 Attach the defective drive to your Atari computer as drive number 2 STEP 8 From GT DOC select drive number 2 for testing STEP 9 From GT DOC select the LED test menu item J STEP IO Visually verify that the BUSY LED is illuminated STEP 11 Press the ESC key and verify that the BUSY LED extinguishes properly If the power supply voltages measured in STEP 4 and STEP 6 are not within the allowed range Repeat the entire test sequence with another power supply If the voltage measurements in STEP 4 or STEP 6 fail again replace the WART board and repeat the test sequence again If the BUSY LED does not light then replace the front panel Repeat the above test If the results are the same replace the UART board and repeat the test Section 6 Page 6 3 GT Field Service Manual If the BUSY LED fails to extinguish verify that the UART board has the latest version of the drive control ROM see section 4 14 If the latest ROM is installed and the BUSY L
78. tach an INDUS power supply to the drive and turn the power ON The LED display should flash through a series of codes beginning with C then stop on track 00 for a few seconds and finally come to rest on track 39 The drive motor should come ON during his sequence and turn OFF at the end Note any deviation from this sequence Section 3 Page 3 1 GT Field Service Manual The next step is to try to determine if the defect is due to an electrical fault or a mechanical one Electrical faults are divided into three categories power analog and digital We will discuss the potential power problems first and then the more prevalent mechanical faults This chapter will then discuss the drive s internal diagnostics which can help you isolate some of the more common digital problems The next chapter extends the discussion into using a special diagnostic Atari program GT DOC which can help you analyze much of what the drive is doing 3 2 POWER SUPPLY PROBLEMS Power problems are usually the simplest ones to diagnose and repair Power problems fall into one of three major groupings The external power transformer is the source of most power related problems Occasionally the power input connector in the drive may be the culprit If you are lucky the power problem won t be due to a defect in the power circuit on the UART board 3 2 1 External Power Transformer The INDUS GT external power transformer should have an output of somew
79. the Analog Board INDUS GT ATARI MODEL Page 2 7 Section 2 GT Field Service Manual Connector J2 is the large 20 pin bus connector you will find on the back end of the board Grasp the female mating connector with your thumb and forefinger Now rock it back and forth while trying to pull the connector off of the board The connector fits very snugly so you will have to use more force than you have up to now Be careful to remove the connector evenly or you will bend the pins on the analog board Once you have removed this connector gently remove connectors 1 a 4 pin connector and J3 a 6 pin connector which are located close to J2 They should come off easily once you get a good firm grip on them Okay you are now ready to remove the last connector Look toward the front of the board You should see a 5 pin connector J0 that is snugly mated with a right angled plug Remove this one in the same way you removed J1 and J3 On some of the older versions of the drive you may have to bend the pans ofthe plug up a little to be able to work the connector free Once you have disconnected this last connector the board can easily be lifted free of the TANDON drive mechanism Go back now and look at the board Notice that the labels don the board for the connectors don t quite match the labels on the connectors you Just removed The
80. the system clock is polled again to derive the elapsed time The RPM number displayed on the monitor screen is the instantaneous translation of how long it takes the timing hole to make one complete revolution This method is accurate to within one tenth of an RPM and should be close to the Address Mark results Pressing the ESC key will immediately return you to the main menu When you enter this menu function you will be prompted to select either the Address mark method or the Index mark method Enter either an A or an T to begin the test Pressing ESC at this point will return you to the main menu Once the test starts two scales will be displayed on the screen and the particular option you selected will be displayed in the top center of the screen The first scale ranges from 8 to 576 RPM with a scale factor of 15 RPM per division The second scale ranges from 278 to 386 RPM with a scale factor of one RPM per division The RPM test in both cases is continuous so you can leave the test running while you are adjusting the drive speed Section 4 Page 4 4 TWO 1 Field Service Manual Theoretically the RPM reading should be 288 RPM plus or minus four RPM If the speed check shows that the drive speed is too fast too slow or varies more that five RPM between each read then you should open the drive and adjust the RPM to within the acceptable range we recommend that you adjust the speed to 288 plus or minus one RPM A variation in the RPM of
81. then proceed to execute its normal built in diagnostics before returning to normal status Read write Head Trap For Shipping This modification really solves a potential problem When the protective cardboard shipper is inserted into the drive it forces the read write head back against the track zero stop This traps the read write head so it will not get knocked out of alignment during shipment Previous versions of the EPROM upon power up would step the read write head out until the track zero sensor came on to RESTORE operation and then consider the read write head to be properly set on track zero However if the cardboard insert had forced the read write head back past the proper track zero position track negative one the track zero sensor would still be active and the drive would think the read write head to already be on track zero The current version of the EPROM performs this same power on sequence but follows it with a step in sequence to track four and then restores the read write head back to the track zero sensor a second time Section 4 Page 4 11 1 Field Service Manual Dual Density Sector Number Correction Previous versions of the EPROM failed to take the dual density mode into account when determining whether or not the absolute sector number was valid For both single and double density valid sector numbers range from 1 to 728 In dual density the valid sector range is 1 to 1848 The error in the EPROM
82. ts the bus interface by driving these two shorted sections of the MOLEX connector with high amp high high amp low low amp high and low amp low signals on the CLOCKIN and DATAIN lines These signal labels by the way are taken from the 400 800 technical reference manuals which were published by Atari If all six of these signals do not respond accordingly the test fails and the drive will display H4 The table below is a quick checklist of the possible combinations SHORT 12 7 HLHD HILO LO LO SHORT 3 5 10 HLHD HILO LO LO Section 3 Page 3 13 GT Field Service Manual 3 5 2 C5 HS5 interrupt Circuitry Test The WART tests its interrupt circuitry by driving the CLOCKIN line labeled from the Atari computer s viewpoint to control the CMD line during the following test sequence 1 The interrupt vector is initialized to point to a routine which simply loads the accumulator A with BFFH and then returns from the interrupt 2 The stack pointer SP is initialized to the end of the static RAM so it will be possible to return from interrupts Of course for this to work the RAM has to be good 3 The CMD line is set inactive high via the CLOCKIN line 4 The interrupt requests IRQs are enabled EI and a no operation NOP is performed to give any latched IRQs a chance to be processed Any such IRQ will run through the special self test interrupt service routine ISR but the f
83. uld also cause performance problems of this kind Section 3 Page 3 7 1 Field Service Manual 3 4 LEVEL ONE INTERNAL DIAGNOSTICS The WART is designed to perform one of two power on self tests POST These tests are normally referred to as the LEVEL ONE internal diagnostics and the LEVEL TWO internal diagnostics This section will discuss the LEVEL ONE diagnostics in some detail The LEVEL TWO diagnostics will be discussed in the next section You will find that these two built in diagnostic programs can save you a lot of time when it comes to finding bad ICs The LEVEL ONE diagnostics are always performed whenever the drive is powered up This diagnostic performs a quick check on several of the major ICs The specific test sequence is as follows 1 Z80A processor flag testing and partial primary accumulator A test 2 Z80A primary accumulator A test ps 280A primary and alternate 8 bit utility registers B C D E H L A B C D E H L and interrupt register I test 280A stack pointer SP test Control ROM EPROM checksum test Ouick SRAM static RAM test 280A index registers IX IY test Floppy disk controller FDC test o B You should understand at this point that if one of the self tests fails that does not necessarily mean that the component which is undergoing the test is detective The device s supporting circuitry may be at fault Howe
84. ver replacing that component is probably a quick and easy first step you could try All of the internal diagnostics except for the main Z80A processor tests items 1 through 4 above display a special code on the drive s LED display prior to the beginning of each test This code always starts with a capital letter and ends with a single digit number between zero and three 0 7 2 3 forthe LEVEL ONE diagnostics Section 3 Page 3 8 GT Field Service Manual Since all of the LEVEL ONE tests are performed faster than the human eye can Follow the displays are provided as a diagnostic aid Just in case the drive goes off in the weeds before a test is completed Should a test be completed but fail the is changed to an H testing Halted at test U 7 2 2 and the drive stops Whenever such a halt occurs the drive sends a tone to the host Atari computer over the audio line to alert you that a problem has occurred 3 4 1 Z80A Processor Tests Since the Z80A processor cannot be relied upon to perform correctly if it fails any of its self tests the Z80A is simply instructed to HALT not the same as the Halt we Just discussed whenever a failure is discovered in the initial test series This means that the disk drive simply will not work at all if the Z80A is defective this is better than corrupting a disk With the proper tools logic probe or oscilloscope you can detect a Z80A test failure by monitoring the Z80As
85. y a field service technician not an electronics engineer Hence the topics covered in this manual are very general and do not delve into the theory of operation of each circuit Virtually all of the repairs detailed in this manual can be accomplished without knowledge of electronics Repairs as detailed in this manual go down to the IC chip level This means that you are not expected or authorized to replace such things as capacitors or resistors At the end d4 this manual you will find an authorized parts list 1 an item is not on that list then you are not supposed to replace repair it If you find a fault in one ofthe electronics boards that is not covered in this manual you are expected to return the board to INDUS Systems for repair A replacement board will be shipped to you upon receipt ofthe defective board Section 1 Page 1 10 GT Field Service Manual Chapter 2 Disassembly and Reassembl1y The INDUS GT Atari disk drive is easy to disassemble and re assemble provided you follow a few simple guidelines This section specifies the tools and procedures you will need Most of the necessary steps will be obvious to you after you have gone through them once or twice Each disk drive can be thought of as a collection of COMPONENTS which are put together into various ASSEMBLIES which in turn are mounted on a CHASSIS and then enclosed in a HOUSING Figures 2 1 and 2 2 show exploded views of the drive 2 1 EQUIPMENT NEE

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