Panasonic JU-475-4 User manual

ORDER NO. MSD891122000
S e rv ic e M anual
Flexible Disk Storage Drive
JU-475-4
Panasonic

CONTENTS
PART I Page
1. INTRODUCTION ...................................................................................................................................................................... 1
2. MODELS AND MODEL NUMBERS ...................................................................................................................................... 1
2.1 5.25inch FDD Series................................................................................................................ 1
3. SPECIAL TOOLS ...................................................................................................................................................................... 1
4. OUTLINE OF M AINTE NAN CE................................................................................................................................................ 2
4.1 Alignment Diskette ................................................................................................................................. 2
4.2 Exerciser .................................................................................................................................................... 2
5. DIAGNOSTIC PROCEDURES .................................................................................................................................................. 2
5.1 Error Symptom Recognition .................................................................................................................... 2
5.2 Soft Error Detection and Correction ....................................................................................................... 2
5.3 Write Error ................................................................................................................................................. 2
5.4 Read Error .................................................................................................................................................. 3
5.5 Seek Error .................................................................................................................................................. 3
5.6 Interchangeability Error .......................................................................................................................... 3
6. TROUBLE ANALYSIS .............................................................................................................................................................. 3
6.1 Trouble Analysis Procedure .................................................................................................................... 3
6.2 Troubleshooting Flowchart .................................................................................................................... 4
6.3 Trouble Analysis Table .............................................................................................................................. 5
7. PREVENTIVE MAINTENANCE .............................................................................................................................................. 6
8. SPECIFICATIONS .................................................................................................................................................................... 6
9. ADJUSTMENTS AND VERIFICATIONS ................................................................................................................................ 7
9.1 Motor Speed Verification (Index Period) ................................................................................................ 7
9.2 Write Protect Verification ........................................................................................................................ 7
9.3 Head Output Verification ........................................................................................................................ 7
9.4 Output Modulation Verification ............................................................................................................. 8
9.5 Resolution Verification ........................................................................ 8
9.6 Radial Alignment Verification and Adjustment .................................................................................... 8
9.7 Azimuth Verification ............................................................................................................................... 9
9.8 Index Burst Verification and Adjustment .............................................................................................. 10
9.9 Track 0 Sensor Adjustment ...................................................................................................................... 10
9.10 Asymmetry Verification ............................................................................................................................ 11
10. TEST P O IN TS ............................................................................................................................................................................ 12
11. PANASONIC ALIGNMENT DISKETTE .................................................................................................................................. 13
PART II
12. REMOVALS AND INSTALLATIONS ...................................................................................................................................... 14
12.1 PCB Removal and Installation ................................................................................................................... 14
12.2 Front Plate and Handle Removal and Installation ................................................................................. 14
12.3 Track 0 Sensor Removal and Installation ................................................................................................ 15
12.4 Collet Assembly Removal, Installation, and Adjustment ..................................................................... 15
12.5 Clamp Assembly Removal and Installation ............................................................................................ 16
12.6 Write Protect Sensor Assembly and Index Sensor Assembly Removal and Installation ..................... 16
12.7 Cartridge Guide Assembly Removal and Installation ........................................................................... 17
12.8 Stepper Motor Assembly Removal and Installation ............................................................................. 18
12.9 Head Carriage Assembly Removal and Installation ............................................................................. 18 — 19
12.10 Drive Motor Removal and Installation ........................................................................... 20
12.11 LED Assembly Removal and Installation ................................................................................................ 21
12.12 Lifter Unit Removal and Installation ....................................................................................................... 21
12.13 Media Lifter Removal and Installation .................................................................................................... 22
12.14 Media Sensor Assembly Removal and Installation ................................................................................. 22
13. EXPLODED VIEW .................................................................................................................................................................... 23
14. REPLACEMENT PARTS LIST .................................................................................................................................................. 24
15. REPLACEMENT PARTS LIST FOR PCB .................................................................................................................................. 2 5 - 2 6
16. SCHEMATIC DIAGRAM ........................................................................................................................................................ 27
17. CIRCUIT BOARD ...................................................................................................................................................................... 2 8 -2 9
18. BLOCK DIAGRAM .................................................................................................................................................................. 30
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PART. I
1. INTRODUCTION
This service manual consists of tw o parts. Part I covers maintenance description, adjustm ent
procedures, and trouble analysis and Part II covers disassembly and reassembly procedures, parts
list, and PCB circuits.
Part I encompasses maintenance instructions for all Floppy Disk Drive (FDD) models. Refer to the
highlighted applicable items, and perform maintenance work on the FDD.
Note : This service manuals is prepared fo r maintenance of the FDD.
Do not use this manual forju d g in g pass or fail criteria in inspections.
2. MODELS AND MODEL NUMBERS
2.1 5.25inch FDD Series
5,25INCH FDD 48TPI
96TPI
3 SPECIAL TOOLS
JA-551
JU-455
JA-56X
JU-58X
JU-595
JU-465
JIM 75
JA-560
JA-561
JU-581
JU-585
The following special tools are used fo r FDD maintenance.
Table 3 -1 Special Tools
Tool
Part No.
Quantity
5.25 inch (48TPI) 5.25 inch (96TPI)
JA-551/JU-455 JA-561 /JU-465 JU-595 /JU-475
Exerciser FDD-EXT-35 *<- 1
Alignm ent diskette 817-128 817-560
*(fr~
1 ~2
Data diskette 2D 2DD 2DD/2HD 1 ~2
Oscilloscope (50 MHz) 1
Probe(10:1) 3
Frequency counter 1
Note: *«- : Stand for the same as left.

4. OUTLINE OF MAINTENANCE
• The follow ing tools are required for maintenance of an FDD.
4.1 Alignment Diskette
Alignm ent diskette is used for head actuator alignment and index sensor adjustment.
Use the right diskette as shown in Table 8.1.
4.2 Exerciser
The exerciser enables you to make all adjustments and inspections necessary for an FDD. Its
functions include the following.
(1) Seek increment or alternate tracks
(2) Read (but no data compare)
(3) W rite 1F or 2F (All "0"s or " 1 "s)
(4) Head load (5.25inch FDD w ith optional head loader)
(5) Recalibration to track 0
The exerciser has switches and indicators to execute a specified function.
5. DIAGNOSTIC PROCEDURES
5.1 Error Symptom Recognition
Errors that occur because of the wrong operating procedure, wrong programming, the use of a
defective diskette, or soft errors due to external causes, such as contaminated air and random
electrical noise, are often attributed to an FDD failure.
Unless a visual inspection of the FDD reveals an evident assembly fault or a defect, always confirm
errors w ith another good diskette, and another known good FDD.
5.2 Soft Error Detection and Correction
Soft errors are normally caused by the follow ing.
(1) Contamination between read/write heads and diskette. This kind of contamination can be
easily eliminated by the liner in the diskette. Please fo llow the appropriate procedures
provided w ith the cleaning diskette.
(2) Random electrical noise, normally a few microseconds or less.
(3) Small defects in w ritten data and/or track not detected during w rite operation may cause
soft errors during read.
(4) Faulty grounding of the FDD or host system can also cause soft errors.
(5) Wrong motor speed is another cause o f soft errors.
Take the following steps on the controller side to recover from the soft errors mentioned
above.
(1) Read the track again ten times or until the data is recovered.
(2) If step (1) above fails to recover the data, access the adjacent track. Then return the head to
the original track.
(3) Repeat step (1).
(4) Any error th a t cannot be corrected by the above procedure is irrecoverable.
5.3 Write Error
If an error occurs during write operation, it is usually detected during the next revolution by
performing a read operation called w rite check. To correct an error, w rite again and repeat a
w rite check operation. If the result is unsatisfactory after ten or more w rite operations, perform a
read operation on another track to determine whether it is the diskette or the drive that is wrong.
If an error persists, replace the diskette and repeat the above procedure.
If the error still persists, assume the FDD defective. If the error is corrected, the diskette is
defective. It can be throw n away.

5.4 Read Error
Most read errors are soft errors. Data can be recovered by follow ing the recovery procedure in
section 5.2.
5.5 Seek Error
Seek errors are caused by the following.
(1) Stepper m otor or stepper m otor drive circuit is faulty.
(2) Faulty Carriage
There are tw o ways to recover from a seek error. One is to recalibrate to track 0, and seek
back to the original track. The other is to read the ID field, check the track number on which
the head is located, and move the head away from it. Read it again.
5.6 Interchangeability Error
Data which is w ritten by one FDD may not be read by ano ther. This error is called a
interchangeability error, which can be caused mostly by the follow ing reasons, which should be
checked as follows.
(1) Head misalignment: Refer to Adjustments and Confirmation section 9.6.
(2) Head output too low: Refer to Confirmation section 9.3.
(3) M otor speed difference: Refer to Adjustments and Confirmation section 9.1.
(4) Format incom patibility.
6. TROUBLE ANALYSIS
To determine the cause of trouble whether it lies in the FDD, diskette, or controller, replace the
diskette and the FDD with good ones. If the FDD is assumed fau lty as a result, fo llo w the
procedure below.
6.1 Trouble Analysis Procedure
FDD trouble may occur in any of the follow ing ten forms.
(1) Index detection failure
(2) I/O 34pin signal failure (Disk Change/Ready/M edia In/M edia Out)
(3) Track 0 undetectable
(4) No seek
(5) No write
(6) No read
(7) Read error
(8) IN USE LED w o n't light.
(9) W rite protect undetectable
(10) No head load (5.25inch FDD w ith optional head loader)
Check w ith the troubleshooting flowchart in section 6.2.
CAUTION:
Be sure to switch the power o ff before removing an FDD or PCB from the operating system.
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6.2 Troubleshooting Flowchart
Table6 -1 Troubleshooting Flow cha rt
-4 -

6.3 Trouble Analysis Table
Table 6-2 Trouble Analysis
Item Trouble No. Cause $.25indh
1Index detection failure 1Collet part faulty (Replace..........
.
2Drive motor control PCB Replace
3Drive m otor faulty _ , ....
4Index LED faulty Replace
5 Index detector faulty Replace, .......
6Index LED/index detector installation faulty lilllillllil
7PCB m otor on circuit Repair
8PCB index detection circuit Repair
2 I/O 34pin signal failure 1 See Item 1.
2 PCB disk chanqe/ready /M edia in /M edia outciu ciit l i i l i l i i i i i i i i ;
3Track 0 detection failure 1Track 0 assembly , Replace
..........
2 PCB track 0 detection failure Repair
4 No head loading 1See Item 1.
2 See Item 2.
3Head load solenoid , Replace u
4PCB head load circuit Repair
5 No seek 1 Stepper motor Replace
...........
2Guide shaft contamination or damaqed Replace'""""""
3PCB stepper driver circuit Repair
6 No write 1See Item 1.
2 See Item 4.
3 Head disconnected l i i i i i i i i i i i
4Head shorted , Replace
......... „
5 Head load bail height wrong Adjustable
6 PCB write circuit „Repair ....... .
7No read 1 See Item 1.
2See Item 4.
3See Item 6.
4 PCB read circuit
8Read error 1See Item 1.
„„„„„„„„„
2See Item 4.
3 See Item 7.
4 A lig nm ent Adjustable
.....
5 Azimuth 'Unadjustabie'
6 Index burst Adjustable
.....
7Asymmetry Unadjustable
8Limiter Unadjustable
9 Track 0 Adiustab'Je'
10 Head load tim e Adjustable ......
11 Index oeriod Unadjustable
12 PCB read circuit „Repair
............
9IN USE LED
w o n 't lig ht
1LED part Replace' '
2PCB IN USE circuit (Repair
.............
10 W rite protect
failure
1W rite protect part 'Reptace''m,,m,,m
2W rite protect circuit Repair

7. PREVENTIVE MAINTENANCE
No preventive maintenance is necessary for any FDD under normal conditions.
However if adjustments are necessary, the procedures in this manual must be follow ed.
• Adjustments (Refer to Table 8-1)
(1) Make a read/write head radial adjustment at the specified track. (Sides 0,1)
(2) Make an index burst adjustment at the specified track. (Sides 0,1)
(3) Make an azimuth measurement at the specified track. (Sides 0,1)
CAUTION
Do not w rite when using alignm ent diskette. Check tha t w rite protect sensor is properly operating
w ith a data diskette.
Note: Section9 describes the adjustment procedure in detail.
8. SPECIFICATIONS
Table 8-1 Specifications
• MINI (a) type
Drive motor is dual speed type. (300 rpm o 360 rpm)
Item Parameter
JU - 475 - 4AEG
M lN U a ) • mode MAXI - m o d e
TRACK VALU E TRACK v a l u e
1Index period 32 2ÖÖ ± 3.0m s 32 166.7 ± 3 .4 rrts
2O utput level 79 18QmV o r m o re 79 IBOmVor more
3 Modulation 00
79 20% or less OO 79 20% or less
4 Resolution
.... 79 6 0 % o r more
........... 7 9 ...........
60% or more
5Radial Aliqnm ent 32
± 70% — —
6Azim uth '"""""""±"1?........." i i i i l l l l l l
7Index burst 68 250
± I50us
8Track 0 From track 0 to
track 2 and back
Q,6xVrc
TH £ S.9m$ 8 ! ! ! ll! l! l: | l! i8 ! ! ! l l l! ll —
9Asymmetry 79 < 500ns 7 9 < 350ns
10 Head load tim e 00
79 < 50ms —
• MINI (ß) type
Drive m otor is fixed speed type. (360 rpm)
Item Parameter
JU *475»4A<36
M IN I {ß ) - mode MAXI • mode
''t r a c k ''' '""" '''''''''v a l u e '''
..... TRACK VALUE
1Index period 32 166.7 ± 3.4ms ——
2O utput level 79 18QmV or more 79 180 mV or more
3Modulation 00
79 20% or less 00
79 20% or less
4Resolution 79 60% or more 79 60% or more
5Radial Aliqnment 32
t 70% —* —
6 Azimuth 68 ± 18' ——
7Index burst 68 208 + 125us —
8 Track 0 From track 0 to
tr a c k 2 a n d back
0.6xVcc
TH S $+9m s —
9Asymmetry ' " " ' "79
..........
'' < 5 0 0 n s ......
... . .... 79 ... . ....... .
....... < 350ns
10 Head load tim e '00
79
< 50ms —
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9. ADJUSTMENTS AND VERIFICATIONS
9.1 Motor Speed Verification (Index Period)
(1) Insert a diskette, run the motor, and clamp. Refer to the index period column o f Table 8-1.
(2) Step to the specified track.
(3) Connect a frequency counter to the INDEX signal: TP7
(4) Check th a t the frequency counter readings meet the specifications of Table 8-1.
9.2 Write Protect Verification
(1) Check that the exerciser's w rite protect lamp goes on and o ff as a diskette is inserted and
removed as specified in the table below.
Diskette w ith write protect
hole open
Diskette w ith w rite protect
hole closed
OFF ON
(Not write protected) ( w rite protected)
9.3 Head Output Verification
Use a new diskette if possible to identify head failure for this check.
(1) Insert a good diskette.
(2) Run the motor.
(3) Step to the track specified in the output level column of Table 8-1.
(4) Connect the oscilloscope probe as specified below.
CHI CH2 EXT
TP1 TP2 TP7
Invert channel 2 and select the Add mode.
Set vertical deflection to 10 mV/division and horizontal deflection to 20 ms/division.
(5) W rite 2F (all " 1 "s) on the entire circumference.
(6) Check th a t the average output level meets the specifications o f Table 8-1.
w _ Vmax + Vmin
v average ~ 2
If it does not meet the specifications, refer to Item 7 of the Trouble Analysis Table.
-7 -

9.4 Output Modulation Verification
Modulation is calculated by the following formula.
** * | . Vmax - Vmin „«n/n/x
Modulation = ---------------------- x100(% )
Vmax + Vmjn
Using the value obtained in section 9.3, and check that the calculated value meets the
specifications of Table 8.1.
M M axim um voltaqe Value: Vmax
# ............. t t t t t t u T ............. TMinimum Voltage Value: Vmax
:UUU
Fig. 9-1 Modulation
9.5 Resolution Verification
(1) Leave the oscilloscope in the same condition as mentioned in section 9.3.
(2) Resolution is calculated by the following formula.
Resolution = V2F average x100(% )
V1F average
(3) Check that the calculated value meets the specifications of Table 8-1.
9.6 Radial Alignment Verification and Adjustment
Introduction
This adjustment is normally not necessary.
If the mounting screws for the stepper motor loosen, or if parts become defective, or if a
compatibility error occurs, check and readjust according to the following procedure.
Steps(4) to (9) below should be performed regardless o f the type, CE or DAD alignment diskette
used. Use an alignment diskette suitable to the type of FDD to be adjusted according to Table 3-1.
(1) Insert Panasonic alignment diskette.
CAUTION:
Be sure to leave the alignment diskette under room conditions fo r 20 minutes before
adjustment.
(2) Step to the track specified in the radial alignment column of Table 8-1.
(3) Leave the oscilloscope in the same condition as mentioned in section 9.3.
• Cats Eye System
(4) Check the output waveforms fo r sides 0 and 1. They should appear as in Fig. 9-2.
(5) The tw o waveforms should appear in the amplitude ratio in the radial alignment column of
Table 8-1 or better.
(6) If the specified ratio is not satisfied, loosen the tw o m ounting screws for the stepper motor.