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
- i -

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.
-3 -

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 —
-6-

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.

(7) Move the stepper m otor along the base by hand u n til the tw o w aveform s assume
approximately the same amplitude, and retighten the mounting screws. (See Fig. 9-2.)
(8) Step the head outward (track 0) and inward (track 79), and confirm th a t the adjustment has
been completed.
(9) A fter the radial adjustment, be sure to confirm track 0 sensor adjustment as described in
section 9-9.
Note: Alignments on sides 0 and 1 are adjusted at the factory. If they are misaligned, adjust
them to meet the specifications o f Table 8-1.
when A > B
- - - x 100 (%)
when A < B
x 100 (%)
Fig. 9-2 Radial Alignm ent Waveforms (CATS EYE) Fig. 9-2-1 Stepper M otor Mounting Screws
--
-1||1-
- /
A
fit 11 ifjijJ*,H,111t!
•fititl l itufi
- \ f
-’
mll 1-
--
9.7 Azimuth Verification
(1) Insert an alignment diskette. Seek to the track specified in the azimuth column of Table 8-1.
(2) Set the oscilloscope in the same conditions as in section 9.3, and set horizontal deflection to
0.5 ms/division.
(3) Measure as shown below.
(4) Confirm that the measured value meets the specifications in the azimuth column o f Table 8-1.
mP I
i
vij:*:*:- Ä
s|§ W
I f
*
§
ill
H
m
When B = C When B>C When B<C
Azim uth = 0' Azimuth =
_ B -C
B -D x (A) Azim uth = ——— x (A)
C -A
Fig. 9-4 Azimuth Waveforms
(A ): 12'

9.8 Index Burst Verification and Adjustment
(1) Insert an alignment diskette. Seek to the track specified in the index burst column o f Table
8-1.
(2) Set the oscilloscope in the same conditions as in section 9.7, and set horizontal deflection to
50ps/ division.
(3) Check th a t the tim e from oscilloscope start to the firs t data meets the index burst
specifications o f Table 8-1.
(4) If the specifications are not met, adjust as follows.
• Loosen the index detector m ounting screws enough to free the assembly.
• Adjust the tim ing to meet the specifications o f Table 8-1.
• Retighten the screw.
• Check the tim ing again.
9.9 Track 0 Sensor Adjustment
(1) Set the oscilloscope as follows.
TRIG SYNC CHI CH2 VERT HORIZ
INT i l l ! ! TP12 TP 8
:
.............
0.2V 1 ms
(2) Step between specified tracks at in the track 0 item of Table 8-1. (Turn the seek delay switch
on the exerciser to adjust 3 ms seek.)
(3) Loosen the track 0 sensor screw and adjust until the waveform on the oscilloscope appears as
shown in Fig. 9-6.
-10 -

9.10 Asymmetry Verification
(1) Insert a work diskette.
(2) Step to the track specified in the asymmetry item of Table 8-1.
(3) Set the oscilloscope as follows.
TRIG SYNC CH 1 CH 2 VERT HORIZ
INT 1 1 1 ! ! I I I ! ! ! TP 1 0.1 V IjjiS
(4) W rite 1F.
(5) A read waveform is displayed on the oscilloscope as shown in Fig. 9-7.
(6) Confirm if it satisfies the value as shown in Fig. 8-1.
Fig. 9-7 Asymmetry Waveform

10. TEST POINTS
Printed Circuit Board
(Top View)
GND Vout Vout
GND + TRK0
TP 8
kJ
-1 2 -

11. PANASONIC ALIGNMENT DISKETTE
Table 10-1 Panasonic Alignment Diskette
TPI Part No. Index
Burst Azimuth Radial
Alignm ent Model
48 817-128 34TRK 34TRK 16TRK JA-551
JU-455
817-560 68TRK 68TRK 32TRK
JA -5 61
JÜ-465
JU“ $95
JU-475

PART. II
12. REMOVALS AND INSTALLATIONS
12.1 PCB Removal and Installation
(1) Remove the four shield plate mounting screws
and take out the shield plate.
(2) Remove the one PCB mounting screw.
(3) Disconnect the connectors (J3 CON, J4 CON, J5
CON, J7 CON, J8 CON) from the PCB.
(4) To reinstall, reverse the above procedure.
(5) Readjustment is n o t necessary a fte r PCB
replacement.
Caution of the cable leading
Let the cable pass under the C guide. Hook the cab|e t0 the
rib projected on the
base.
The cable shall not
protrude above
the upper face of
the drive. (Make it
flat by pressing
with a finger.)
Do not damage or
disconnect the pig
tail by pressing it
forcibly into the
much in the PCB.
Fig. 12-1-2 Cable Leading
12.2 Front Plate and Handle Removal and
Installation
(1) Operate the lock cam of the clamp assembly,
and turn the clamp handle in the direction of
clamping.
(2) Remove the clamp handle.
(3) Remove the tw o fro nt plate mounting screws,
and take o ff the front plate.
(4) Reverse the above procedure to reinstall.
Lock Cam
Fig. 12-2 Front Plate and Handle Removal
Do not let the pig
tail bitten or
disconnected.
-1 4 -

(1) Remove the shield plate as described in section
12.1 step (1).
(2) Disconnect the J3 connector from PCB.
(3) Draw out the pins the track 0 sensor assembly
from the following locations on the J3
connector: No2,4, 6.
A t that time, draw out the pins w ith liftin g the
stopper on the connector.
(4) Remove the track 0 sensor assembly mounting
screw and take out the track 0 sensor assembly.
(5) Reverse the above procedure to reinstall.
(6) A fter reinstallation, adjust the track 0 sensor as
described in section 9.9.
12.3 Track 0 Sensor Assembly Removal and
Installation
Fig. 12-3 Track 0 Sensor Assembly Removal
12.4 Collet Assembly Removal, Installation and
Adjustment
(1) Remove the cartridge guide assembly as
described in section 12.7.
(2) Remove the lifter unit as described in section
12.12
(3) Remove the collet assembly from the guide
shaft.
(4) Reverse the above procedure to reinstall.
(5) A fter reinstallation, perform collet assembly
center adjustment.
(6) Collet assembly center adjustment.
a) Temporarily fasten the cartridge guide
assembly.
b) Insert a diskette or dummy diskette and
clamp it.
c) Clamp repeatedly a few times to find a
good fit between the collet and the inside
diameter of the drive motor.
d) Bind the screws o f the cartridge guide.
e) Check step c) again, if not good repeat step
a) through d) until the correct center
adjustment is achieved.
-1 5 -

12.5 Clamp Assembly Removal and Installation
(1) Remove the fro nt plate as described in section
12.2.
(2) Remove the shield plate as described in section
12.1 step (1).
(3) Remove the tw o clamp assembly mounting
screws and take out the clamp assembly.
(4) Reverse the above procedure to reinstall.
(1) Remove the shield plate as described in section
12.1 step (1).
(2) Disconnect the J3 connector from PCB.
(3) Draw out the pins of the w rite protect sensor
assembly from the follow ing locations on the
J3 connector: N o 9 ,11.
At tha t time, draw out the pins w ith liftin g the
stopper on the connector.
(4) Draw out the pins of the index sensor assembly
from the follow ing locations on the J3
connector: No5, 7.
At that time, draw out the pins w ith liftin g the
stopper on the connector.
(5) Remove the w rite protect sensor mounting
screw and index sensor mounting screw
respectively.
(6) Reverse the above procedure to reinstall.
(7) When reinstalling the write protect sensor,
exercise care so th a t the leads and w rite protect
sensor w ill not project from the bottom and
side of the base.
(8) A fter index sensor installation, adjust the index
burst as described in section 9.8.
12.6 Write Protect Sensor Assembly and Index
Sensor Assembly Removal and Installation
Fig. 12-5 Clamp Assembly Removal

(1) Remove the PCB as described in section 12.1.
(2) Remove the handle and fro n t plate as
described in section 12.2.
(3) Remove the clamp assembly as described in
section 12.5.
(4) Remove the w rite protect sensor m ounting
screw.
(5) Remove the three cartridge guide mounting
screws and take out the cartridge guide
assembly.
(6) After reinstallation, adjust the collet assembly
as in section 12.4 step (6) and adjust the index
burst as in section 9.8.
(7) When removing or reinstalling, be careful not
to damage the carriage arm w ith the lifter.
12.7 Cartridge Guide Assembly Removal and
Installation
-1 7 -
Fig. 1 2-6 W rite Protect Sensor Assembly and
Index Sensor Assembly Removal

12.8 Stepper M o tor Assem bly Rem oval and
Installation
12.9 Head C arriage Assembly Rem oval and
Installation
(1) Remove th e head c a rria g e assem bly as
described in section 12.9.
(2) Remove the tw o stepper m o tor assem bly
mounting screws.
(3) Remove the stepper m otor and stepper motor
stopper.
(4) Reverse the above procedure to reinstallation.
(5) A fter reinstallation, adjust the radial alignm ent
and track 0 sensor as described in section 9.6
and 9.9.
Stepper Motor Assembly
Fig. 12-8 Stepper M otor Assembly Removal
(1) Remove the PCB as described in section 12.1.
(2) Remove the one pig tail clamp mounting screw.
(3) Remove the tw o guide rod clamp m ounting
screws.
(4) Remove the head carriage assembly, guide rod
clamp, guide rod, and pig tail clamp.
(5) Pull out the guide rod from the head carriage
assembly.
(6) Reverse the above procedure to reinstall.
(7) A fte r reinstallation, adjust the radial alignm ent
and track 0 sensor as described in section 9.6
and 9.9.
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