Panasonic JU-253-T User manual

ORDER NO. MSD870909100
erviceManual
Flexible Disk Storage Drive
3.5 Inch
JU·253·T/JU·253·P/JU·253·PK
•
IC

CONTENTS
Page
PART 1
1. INTRODUCTION ······························ ······ ·· ················································ ·. · .. ··· .. ·. · .. · ........ .
2. MODELS AND MODEL NUMBERS ···· ····· · ····· ····· ··· ·· ··· ·· ···· · ..... ·· ..... ··· .... · .... ··· ..•.. .. ... . .... ... ..... ...... 1
3. SPECIAL TOOLS ·················· ·· ······ ············································.· ·. ·....... •............................... 1
4. OUTLINE OF MAINTENANCE ···· ······ · ····· · ···· ····· ·· ··· ·· ····· · .... ··· ···· ··•·· ... · ...... ··.. ... . .... ..... ....... ..... ... 2
5. DIAGNOSTIC PROCEDURES ················ ················································································· 2
5.1
5.2
5.3
5.4
5.5
Error Symptom Recognition ··· ·· ··· ·········· ···················· ············ ................................... .
Soft Error Detection and Correction -· ···· .. ··. ··· ................ ·· ............................................ -
Write Error
Read Error
Seek Error
2
2
2
3
3
5.6 InterchangeabilityError .............. ·····························-·· ·······-······· .......... ..................... 3
6. TROUBLE ANALYSIS · ··· ·· ····· ···· ····· ······· ··· ·· ··· ·· ···· · ···· ······ ·· ····· ·· ·· ·· ··· ······ · ··· ········· ··· ·· ··· ··· ···· ··. 3
6.1 Trouble Analysis Procedure ·· ····- ···· · ····· ·· ··· ·····.· ··· ·········· ····· .. ··· ······· ··· ·· ··· ·· ... ·· ··· ·· ··· ·· ··· · 3
6.2 Trouble Shooting FlowChart -· -·· ··. · ···. · ···· ······ ···· ··· ·· ···· · ···· ··· ···· ··· ·· ····· ······· ····· ·· ····· ····· · 4
6.3 Trouble Analysis Table ... ··· ..... ····· ····· ·· ... ··· ···· ····· ····· ·· ··· ······· ··· ····· ·· ·········· ··· -· ···· ··· ··· ··· 5
7. PREVENTIVE MAINTENANCE -······························································································· 6
8. MEASUREMENT ITEMS ··· ·· · ···· ······· ··· ········· ··· ·· ····· ·· ···· ······ ··· ··· ··· ·· ··· ····· ·· ··· ·· ···· ··· ··· ···· ···· ···· ···· 6
9. ADJUSTMENTS AND VERIFICATIONS ··················································································· ···· 7
9.1 Motor Speed Verification (Index Period) ·· ····· ··· ·· ·· ··· ····· ······· ···· · ······· ·········· ·· ····· ····· ····· ·· ·· 7
9.2 Write ProtectVerification ······· ·· ·· ··· ······· ··· ······· ··· ···· ··· ··· ·· ···· ······ ····· ··· ·· ·········· ·· ··· ····· ···
9.3 Head Output Verification .......•.................................................................................
9.4 Output Modulation Verification .. ·· ............•.... ··· ·· ..•...................................................
9.5 Resolution Verification ...........................................................•...............................
9.6 Radial Alignment Adjustment .......... ·· ····· ··· ·· ····· · ···· ····· ···· · ·········· · ···· · ···· ·········· ·· ··· ·· ··· ··
9.7 Azimuth Verification .............................................................................................. .
9.8 Index Burst Verification and Adjustment ···· ··········· ··· ··· ······· ···· · ·· ··· ·· ··· ·· ····· ·· ···· · ····· ·· ····· ····
9.9 Track 00 Sensor Adjustment .... · ... · .... ·· .......... ·. ··· ····· ·· ................................................ .
7
8
7
8
8-9
9-10
10
10-11
9. 10 Asymmetry Verification ············································ ·· ············· ·· ······························· 12
10. TEST POINT ············································································•····································•· 13
11. PANASONIC ALIGNMENT
DISKETTE
PART 2 [JU-253-T]
12. DISASSEMBLY AND REASSEMBLY
12.1 Removing and Remounting the Cover .......................................................................... .
12.2 Removing and Remounting the Front Panel Assembly ....................................................... .
12.3 Removing and Remounting the Guide Plates ................................................................... .
12.4 Removing and Remounting the Holder Assembly and Rollers ............................................... .
12.5 Removing and Remounting the Head FPC, Track 0 Connector,
and Stepper Motor Connector ................................................................................ .
12.6 Removing and Remounting the Head Carriage Assembly, Rod Clamp, and Guide Rod .................. .
12.7 Removing and Remounting the Track 0 Assembly ............................................................ .
12.8 Removing and Remounting the Stepper Motor •...................•..........................................
12.9 Removing and Remounting the Trigger Lever Assembly ..................................................... .
12.10 Removing and Remounting the Eject Lever Springs .......................................................... .
12.11 Removing and Remounting the EjectLever .................................................................... .
12.12 Removing and Remounting the Shield Plate ................................................................... .
12.13 Removing and Remounting the Microswitch Assembly ....................................................... .
12.14 Removing and Remounting the Mounting Brackets ..............•...........................................
12.15 Removing and Remounting the Control PC Board ............................................................ .
12.16 Removing and Remounting the Drive Motor Assembly ....................................................... .
12.17 Disassembling and Reassembling the Mounting BracketAssembly •.........................................
12.18 Removing and Remounting the Pushbutton ................................................................... .
12.19 Disassembling and Reassembling the Holder Assembly ....................................................... .
11.20 Mounting the Drive Motor LED
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Page
(JU-253-P/-PK]
12. DISASSEMBLY AND REASSEMBLY
22
12-1 Removing and Remounting the Cover .••.••.•.. .. .•. ..••. ..•..• .••• •• ..• ..••. •.•.•. •..• •••.... ••.. •• •• .. •.. .••.. •.•.••..•.. 22
12.2 Removing and Remounting the Front Panel Assembly ................................................... ~............... 22
12.3 Removing and Remounting the Holder Assembly and Rollers.......................................................... 22
12.4 Removing and Remounting the Head FPC, Track OConnector, and Stepper Motor
Connector ··························'····························································································
12.5 Removing and Remounting the Head CarriageAssembly, Rod Clamp, and Guide Rod ............................ .
12.6 Removing and Remounting the Track 0 Assembly ••.•..•.••..•.....•......••••.•.•...••••••••...•.•.••••..••••.•••••••••••
12.7Removing and Remounting the Stepper Motor ....................................................................... .
12.8 Removing and Remounting the Trigger LeverAssembly ................................................................ .
12.9 Removing and Remounting the EjectLever Springs .................................................................... .
12.10Removing and Remounting the EjectLever •.••...••••••...••.••.••...••••••••.•.••••.••••.••...• ., .••••.•.••.••••••.••••
12.11 Removing and Remounting the Microswitch Assembly ....•.....•.•....•••........••...•.•.••.••.•...•...•..•.....•••..
12.12 Removing and Remounting the Mounting Brackets ................................................................... .
12.13 Removing and Remounting the Control PC Board ..............•.........••.....•.•.••..•.•.••.•••.•..•.•.•..•.•...•.•..
12.14Removing and Remounting the Drive Motor Assemmbly - ........................................................... .
12.15 Disassembling and Reassembling the Mounting BracketAssembly .................................................. ..
12.16 Removing and Remounting the Pushbutton ............................................................................ .
12.17 Disassembling a.nd Reassembling the Holder Assembly ................................................................. .
12.18 Mounting the Drive Motor LED .............•....•....•...............•...•.•...•...••...••...••.••••.......••...•.•.•..•.•.
13. EXPLODEDVIEW1-1 (JU-253-01T] .•......•.••....•.......•.....•......•.•..•••..••••.•••••••••••••••••.•.•.••.•..••..•••..••••.••.
EXPLODED VIEW 1-2 (JU-253-01T] •······•····•····•·•····•··•········•·····••·······•••·•••·••••··••••••••••••··•·•·••••·•••·•••··
EXPLODED VIEW 2-1 (JU-253-01 P/-01 PK] .•..................• , .•..•.•.•• , ..•...•••••...•.•••••. , ................................ .
EXPLODED VIEW 2-2 [JU-253-01 P/-01 PKj ......•...••.....•..•..... ; .............................................................. .
14. REPLACEMENT PARTS LIST 1-1 Model: JU-253-0n ............................................................................. .
REPLACEMENT PARTS LIST 1-2 Model: JU-253-01p ·•··•·•••·•••· ..••••.••..•..••...•..•••..•....•.••...•••.••....•.••.•.•..•.••
REPLACEMENT PARTS LIST 1-3 Model: JU-253-01PK····· .••.........•....•.•..•...••..•.....••....••.•.•.•..•.•..•..•......•...
REPLACEMENT PARTS LIST OF PCB 2-1 Model : JU-253-01T/-01 P••••••••.•••••.••••••••••••••••••.••••••••••••.••••••.•.•.•••.
REPLACEMENT PARTS LIST OF PCB 2-2 Model : JU-253-01 PK··· .............................................................. .
15. SCHEMATIC DIAGRAM OF CONTROL BOARD [JU-253-0H/-01 P] ..... ·· ··•···· ............ ·········•·•·· ·· ······•····· ·· ··•·
SCHEMATIC DIAGRAM OF CONTROL BOARD (JU-253-01PK] •.•....•.•.............•..••...•..•..•.•.••••....•.•.....•...• •·
16. CIRCUIT BOARD (JU-253-01T/-01 P] ..•................•......••........•....•.•...••..............•...••...•.•••••••.••.•.•••....•.
CIRCUIT BOARD (JU-253-01 PK] .....•••..•.•..••.•........•...•..•................•••....•.•••.......•..•.•.•..•....•..•••.•••.•••..
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PART. 1
1. INTRODUCTION
This service manual consists of two parts. Part 1 covers maintenance description, adjustment procedures,
and trouble analysis and Part 2 covers disassembly and reassembly procedures, parts list, and PCB circuits.
Refer to the highlighted applicable items, and perform maintenance work on the Floppy Disk Drive (FDD).
Note:
This service manual is prepared for maintenace of the Floppy Disk Drive.
Do not use this manual for judging pass or fail criteria in inspections.
2. MODELS AND MODEL NUMBERS
2.1 3.5-inch FOO Series
::::::ii!~j~ji,~.:~B~· .. :iii:,,_; --------...-- 67.5TPI ----
L_,,_:' -~-
JU-31X
----.-- JU-312
c= JU-313
L_ JU-314
JU-32X JU-322
EJU-323
JU-323A
JU-324
JU-36X JU-362
EJU-363
JU-363A
JU-364
JU-38X ---- JU-386
JU-39X ---- JU-394
::1:1:1:1?:~~~:?:~::::::::, ... : -...,--- JU-252A
JU-253A
•
3. SPECIAL TOOLS
The following special tools are used for FDD maintenance.
TABLE 3.1
P/No.
Tool JU-252A JU-31 X,32X,36X,
JU-253A JU-323A,363A
*~
.. ~
*~
*~
*~
*~
*~
*~
*~ *~
*~
YTFDD-SB35
Test Pin Jig For PCB
YTFDD-TPIN25 YTFDD-TPIN35
DAD Alignment Tester
Oscilloscope (SOM Hz}
Probe (10:1)
Frequenc Counter
Note: *~ : Standforthesameasleft.
DAD : Dynamic Alignment Diskette
CE : Cats Eye
-1-
JU-38X
JU-39X
2DD I 2HD
Quantity
1-2
1-2
3

4. OUTLINE OF MAINTENANCE
•The following tools are required for maintenance of a Floppy Disk Drive.
4.1 Alignment Diskette
Alignment diskette is used for head actuator alignment and index sensor adjustment. Use the right
diskette as shown in Table 3.1.
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) Write 1 For 2F (All O's or 1 's}
(4) Recalibration to track 00
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, or use of a defective
diskette, or soft errors due to external causes, such as contaminated air and random electrical noise, are
often attributed to a drive failure.
Unless a visual inspection of the drive reveals an evident assembly fault or a defect, always confirm errors
with another good diskette, and another known good drive.
5.2 Soft Error Detection and Correction
Soft errors are normally caused by the following:
(1) Contamination between read/write heads and diskette. This kind of contamination can be easily
eliminated by the liner in the diskette. Contaminated heads can be cleaned by a general purpose non-
abrasive head cleaning diskette. Please follow the suitable procedure provided with the cleaning
diskette.
(2) Random electrical noise, normallya few microseconds or less.
(3) Small defects in written data and/or track not detected during write operation may cause soft errors
during read.
(4) Faulty grounding of the drive or host system can also cause a soft error.
(5) Wrong motor speed is another cause of 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 that 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 write check. To correct an error, write again and repeat a write check operation. If
the result is unsatisfactory after ten or more write 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, consider the drive defective. If the error is
corrected, dispose of the diskette as defective.
-2-

5.4 Read Error
Most read errors are soft errors. Data can be recovered by following the recovery procedure mentioned in
5.2.
5.5 Seek Error
(1) Stepper motor or stepper motor drive circuit is faulty.
(2) Faulty carriage
There are two ways of seek error recovery. One is to recalibrate to track 00 , 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. And read it again.
5.6 Interchangeability Error
Data which is written by one drive may not be read by another. This error is called a Interchange-ability
error,which can be caused mostly by the following reason,which should be checked as follows.
(1) Head misalignment: Refer to Adjustments and Confirmation Item 9.6
(2) Head output too low: Refer to Adjustments and Confirmation Item 9.3
(3) Motor speed difference: Refer to Adjustments and Confirmation Item 9.1
(4) Format difference
6. TROUBLE ANALYSIS
FDD trouble may occur in any of the following nine forms.
(1) Index detection failure
(2) Not ready
(3) Track 0 undetectable
(4) No seek
(5) Nowrite
(6) No read
(7) Read error
(8) IN USE LED won't light.
(9) Write protect undetectable
Check with the troubleshooting flowchart in 6.2
CAUTION:
Be sure to switch power off before removing an FDD or PCB from the operating system.
-3-

6.2 Trouble Shooting Flow Chart
START
Run the operatingsystem and
check. Record all diagnostic
Information on tracksandsectors
as far as the programpermits.
Install Exerciser on FDD
Power SW
DC SWON MOT SWON
Drive SelectSW
ON
YES
Media
Defective
Controller
Defective
Check. Item 1,
Table6.1.
Check Item 2,
Table 6.1.
Check Item 3,
Table 6.1.
-4-
END
Check Item 4,
Table 6.1.
Check Item 5,
Table 6.1.
Check Item 6,
Table6.1.
Check Item 7,
Table 6.1.
Check Item 8,
Table6.1.
Check Item 9,
Table 6.1.

6.3 Trouble Analysis Table
Item Trouble
Indexdetection
failure
2
Not ready
3 Track 0
detection failure
4 Noseek
5 No
WRITE
6 No READ
7 READ ERROR
8
IN USE LED
won't light.
9
Write protect
failure
Table6.1
NO
Cause
1 DD motor control PCB
1---1------"'----"----------1 Replace DD motor,
2 DD motor fault
Base assembly
3 IndexLED
fault
1---1-------'""-----------1 Replace DD motor,
4
5
6
1
2
1
2
1
2
3
1
2
3
4
1
2
3
2
3
4
5
6
7
8
9
10
2
2
Index detector fault
PCB motor ON circuit
PCB index detection circuit
See Item 1.
PCB read circuit
Track 00 assembl
PCB track O detection failure
Ste er
motor
Guide shaft contamination or dama
PCBste er driver circuit
See Item 1.
Head disconnected
Head shorted
PCB write circuit
See Item 1.
See Item 5.
PCB read circuit
See Item 1.
See Item 6.
Ali nment
Azimuth
Burst
As mmetr
Limiter
Fla
0
Index period
PCB read circuit
LED art
PCB IN USE circuit
Write protect part
Write
rotect circuit
ed
Base assembly
Re
Re
Re
Re
Re
Re
Re
Re air
Replace DD motor,
Base assembly
Replace DD motor,
Base assembly
Re air
Note: * ~: Stand for the same as left.
-5-

7. PREVENTIVE MAINTENANCE
No preventive maintenance is necessary for any type of FDDs under normal conditions of use.
However ifit is determined that adjustments are necessary,the following must be done.
• Adjustments (Refer to table 8. 1)
(1) Make a read/wtite head radial adjustment at aspecified track. (Sides 0, 1)
(2) Make an index timing adjustment at a specified track. (Sides 0, 1)
(3) Make an azimuth measurement at a specified track. (Sides 0, 1)
CAUTION
Do not write when using alignment diskette. Check that write protect sensor is properly operating with a
data diskette.
Note: Section 9 describes the adjustment procedures in detail.
8. MEASUREMENTITEMS
Item Parameter
1 Index period
2 Output level
3
Modulation
4 Resolution
5 Radial
Alignment
--------------
Reference (DAD)
--------------
Reference
(CE by 817-363CE)
6
Azimuth
7 Index burst
8 Flag 0
9
Asymmetry
Table 8.1
JU-252A, 253A
TRK Value
40 200 ±2 ms
79 80mVormo~
0, 79 20% or less
79 55% or more
40
40
40
From track Oto
track 1and back
79
-----~ _2_5jl_fl2 __ --
(43% or more)
--------------
(55% or more)
±24'
3±1.7ms
TROO (TRO: Low,
TR1 : High)
~ 700 ns
-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 of Table 8.1 for the
applicable model.
(2) Step to the specified track.
(3) Connect afrequencycounter to the INDEX signal.
Index {No. 8 Pin of CMOSffTLAdaptor)
(4) Check that the frequency counter readings meet the specifications in the table.
9.2 Write ProtectVerification
(1) Check that the exerciser's write protect lamp goes on and off as a media is inserted and removed as
specified in the table below.
Media with write protecthole open
Media with write protecthole closed
9.3 Head Output Verification
ON (Write protected)
OFF (Not write protected)
Use a newdiskette 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.
CH1 T1
CH2 T2
EXT: Index (No. 8 Pin of CMOSITTLAdaptor)
Invertchannel 2 and select the Add mode.
Set vertical deflection to 10 mV/division and horizontal deflection to 20 ms/division.
(5) Write 2F (all ones) on the entire circumference.
(In case of adouble-sided FDD, repeat it on sides 0 and 1using SIDE SELECT.)
(6) Check that the average output level meets the specifications of Table 8.1.
V average=
Vmax+Vmin ]
2
If it does not meet the specifications, refer to Item 7 of theTroubleAnalysis Table.
9.4 Output Modulation Verification
Modulation: M is calculated by the following formula.
M(%)= Vmax-Vm~n
Vmax+Vmtn
x 100 using the value obtained in 9.3, and check that the calculated value
meets the specifications of Table 8.1.
Minimum Voltage Value: Vmin
~~~~~~~~~~~t---t--T-~
tt.
Maximum Voltage Value: Vmax
Average Voltage
--Fig.
9.1 Modulation
-7-

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 .
• V2Faverage
V1Faverage x lOO (%)
(3) Check that the calculated value meets the specifications of Table 8.1.
9.6 Radial Alignment 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 of 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 for 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 for sides 0 and 1. They should appear as in Fig. 9.2.
(5) The two waveforms should appear in the amplitude ratio in the RIA ± 55% or more.
(6) If the specified ratio is not satisfied, loosen the two mounting screws for the stepper motor.
(7) Move the stepper motor along the base by hand until the two waveforms assume approximately the
same amplitude, and retighten the mounting screws. (See Fig. 9.2.)
(8) Step the head outward (track O) and inward (track 40 or 79), and confirm that the adjustment has been
completed.
(9) After the radial adjustment, be sure to confirm track 00 sensor adjustment9.9
A>B ~ x 100
B>A ~ x 100
Fig. 9.2 Radial Alignment Waveforms (CATS EYE)
Note: Alignments on sides Oand 1 are adjusted at the factory. If they are misaligned, adjust them to
meet the specifications of Table8.1.
-B-

• DAD (Dynamic Alignment Diskette)
(4) Watch the output waveforms for sides 0 and 1. They should appear as shown in Fig. 9.3.
(5) Measure the timing levels A1 to A4 and B1 to B4 in Fig. 9.3, and calculate the lobe ratio from the
following formulas.
:EB :EA
:EA>:EB: :EA x 100% :EA<:EB:
EB x 100%
(6) The lobe ratio calculated by the above formulas should meet the specifications on item 3 of Table 8.1.
(7) If the above requirement is not met, loosen the two mounting screws for the stepper motor, adjust.
(8) Seek from track 0 to track 40 and from track 79 to track 40, and confirm that the adjustment has been
completed.
(9) After the radial adjustment, be sure to confirm track 00 sensor adjustment 9.9.
Note: A digital alignment test instrument for 3.5-inch FDDs permits accurate and easy adjustment
because the lobe ratio is displayed on the instrument.
Azimuth
waveforms
Index burst Radial
alignment waveforms
Fig. 9.3 Alignment Waveform (DAD)
9.7 Azimuth Verification
(1) Insert an alignment diskette. Seek to the trackspecified in the azimuth column of Table 8.1.
(2) Set the oscilloscope in t)le same conditions as in 9.3, and set horizontal deflection to 2ms/div (DAD) or
0.5 ms/div (CE).
(3) Measure as shown below.
(4) Confirm that the measured value meets the specifications in the azimuth column of Table 8.1.
-9-

caseofB>C (+)
B-C
Azimuth = B _ D x (A)
(A) : CE-+30'
DAD-+15'
Fig. 9.4 Azimuth Waveforms
9.8 Index Burst Verification and Adjustment
Case of C>B(-)
C-B
Azimuth = C _A x (A)
(1) Insertan alignment diskette. Seek to the track specified in the llB column of Table 8.1.
(2) Set the oscilloscope time base as follows:
1ms/division
(3) Check that the time from oscilloscope start to the first data pulse meets the l/B specifications of Table
8. 1. (DAD system)
(4) If Index Burst is not within specification, adjust the variable resister on the motor control PCB.
J
I
o( • ,
Index Burst
Fig. 9.5 Index Timing
9.9 Track00 Sensor Adjustment
[In the case of JU-252A/JU-253A]
(1) Set the oscilloscope as follows.
Set horizontal deflection to 1ms/division.
CH1 ZP
EXT SP
V.R
Fig. 9.6 l/B Adjustment
-10-

(2) Step between specified tracks as shown in the FLAG 0 item of Table 8.1 (Turn the seek delay switch on
the exerciser to adjust 12 ms seek.)
(3) Loosen the track 0 sensor screw and adjust until the waveform on the oscilloscope appears as shown in
Fig. 9.7.
,;.._----1-------1----- VL
A B ADJUST A: B TO 1 : 1
Fig. 9.7 Track 0 Waveform
1
.!~illllll!lllt
1
~ll:~.'lil·-~·11~tlB-l!i.1/~~:
[ 1] Set the oscilloscope as follows.
Set horizontal deflection to 1ms/division.
CH1 : ZP
EXT : Step (No. 20 Pin of CMOSITTL Adaptor)
(2) Step between specified tracks as shown in the FLAGO item of Table 8.1, (Turn the seek delay switch on
the exerciser to adjust 3 ms seek.}
(3) Loosen the screw for track 0 assembly so that the waveform on the osciloscope is as shown in Figure 9.8
and adjust the track 0 assembly position by moving it back and forth.
STEPLJ
3.0ms
Tzp
LJ
.1
O.Bms Max
(Reference)
CP
Vcp
--------------'--------- GND LEVEL
Fig. 9.8 Track 0 Waveform
(4) VoltagesfTimings for track 0 waveform
1.
Tzp
4.2ms
2.
VL
:;;;; 1.0V
3.
VH
~4.0V
4.
Vcp
~3.2V
-11 -

(5) After performing adjustment on items 1to4, reconfirm the following:
CD Recalibrate to track 0
® Step in for 40 steps.
@ Check the alignment waveform.
9.1 O AsymmetryVerification
( 1) Inserta data diskette.
(2) Step to the trackspecified in the Asymmetry item of Table 8.1.
(3) Set the oscilloscope as follows:
CH1 Read Data (No. 30 Pin of CMOS/TTL Adaptor)
CH2 T1
Set time base to 1µs/division and vertical deflection to 0.2 v/division.
(4) Write 1 F.
(5) A read wave form is displayed on the oscilloscope as shown in Fig. 9.9.
(6) Confirm if it satisfies the value as shown in Table 8.1.
Fig. 9.9 Asymmetry Waveform
(AsymmetryWave form might be reversed up-and-down from model to model.)
-12-

10. TEST POINTS
Track 0
ZP
~-
I I
~D ~IJ
@ D
.------- rnrn
Component Side
CMOS I TTL Adaptor [YTFDD -CN35]
Pin
Signal
No.
1
NC (Disk Change Reset)
2 Disk Change (Disk In)
6 Drive Select 3
8 Index
10 Drive Select 0
12 Drive Select 1
14 Drive Select 2
16 Motor On
18 Direction Select
20
Step
22
Write Data
24 Write Gate
26 Track 00
28
Write Protect
30 Read Data
32
Side Select
34 Ready (Disk In/Disk-
change)
-13-

11. PANASONIC ALIGNMENT DISKETTE
3.5 inch Alignment Diskette
Table 11.1
TYPof
TPI
Alignment
P/N
Index
Azimuth
Diskette Burst
DAD JU-01AA
67.5
CE 817-363CE
20TRK 20TRK
135 DAD 817-384 40TRK 40TRK
-14-
Radial
Alignment
20TRK
40TRK
MODEL
JU-31X
JU-38X
JU-39X

PART. 2 [JU-253-T]
12. DISASSEMBLY AND REASSEMBLY
12.1 Removing and Remounting the Cover
(1) Remove the claws in the four corners of the
cover from the base and guide plate and
remove the cover.
(2) To remount the cover, clutch the claws in the
four corners of the cover from the outside.
Cover
Guide Plate
(Left)
'
'
\\ ,,.---/~/
\./
~
Fig.12-1. RemovingtheCover
12.2 Removing and Remounting the FrontPanel
Assembly
(1) Remove the two claws on the left side of the
front panel from the left side guide plate,
remove the two claws on the right side from
the right side guide plate and remove the front
panel.
(2) Remount the front panel in the reverse
procedure of step (1) so that the button is
inserted into the button hole in the front
panel.
Front Panel Assembly .
Fig. 12-2. Removing the FrontPanel Assembly
-15 -
12.3 Removing and Remounting the Guide Plates
(1) Remove the cover and front panel according to
the procedures in sections 12.1 and 12.2.
(2) Remove two set screws on the right side guide
plate.
(3) Lift the right side guide plate so that it is
removed from the roller pinched by the recess
in the guide plate and remove the right side
guide plate through the path between the
eject leverand the base.
(4) Remove the left side guide plate in the same
manner as above.
(5) Remount both plates in the reverse procedure
of steps (1) to (4).
A-Guide Plate (Left)
~ : Guide Plate (Right)
~ ~
~~~ -'\) r,j JEjectlever
:t:::~ I
~ "':;.
/
Roller
Fig. 12-3. Removing the Guide Plates
12.4 Removing and Remounting the Holder
Assembly and Rollers
(1) Remove the guide plates according to the
procedure in section 12.3.
(2) Lift the holder assembly by hands and gently
slide it toward you, then the four roller sections
on the holder will be removed from the eject
levers. { Keep in mind that the rollers drop
easily.) In this case, when the side 1 of the
head assembly drops from the holder, it strikes
the head on the side 0 being pushed by the side
1 head retaining spring, so lift it lightly by the
thumb.
(3) Remove the four rollers from the holder
assembly.
(4) Remount the rollers and holder assembly in the
reverse procedure of steps (1) to (3).

Fig.12-4. Removing the HolderAssembly,and
Rollers
12.5 Removing and Remounting the Head FPC,
Track 0 Connector, and Stepper Motor
Connector
(1) Draw the contact section of the head FPC
upwards out of the head connector J6 by
pinching it by flat pens with care not to
damage it.
(2) Remove the track 0 cable connector (red) from
the connector J3 (on the stepper motor side,
red) on the PCB.
(3) Remove the stepper motor cable connector
(brown) from the connector J4 (on the track 0
side, brown).
(4) Remount the above in the reverse procedure of
steps (1) to (3).
In this case, be sure to insert the head FPC to
the full extent in the right angle. Wiring
should be made so that the lead wire of the
track 0 and the stepper motor does not contact
the carriage of the head or hang over the track
0.
(5) Ensure that the head FPC is not higher than the
track Oassembly.
(6) Ensure that the head FPC does not contact the
head of the track 0 assembly set screw.
Note: FPC: Flexible printed circuit.
-16 -
----·- ---
Fig.12-5.
He•dF~
PC~J
6
Removing the Head FPC, Track O
Connector,and Stepper Motor
Connector
12.6 Removing and Remounting the Head Carriage
Assembly, Rod Clamp, and Guide Rod
(1) Remove the holder assembly according to the
procedure in section 12.4.
(2) Remove the head FPC from the connector J6
according to the procedure in section 12.5.
(3) Remove two set screws on the rod and remove
the rod clamp.
(4) Move the head carriage assembly in the reverse
direction of the stepper motor (rightward) and
remove it.
(5) Draw the guide rod out of the head carriage
assembly.
(6) Remount the above in the reverse procedure of
steps (1) to (5).
[Cautions for Remounting]
(7) Apply oil to the guide rod (but not too much),
insert the rod into the head assembly, move it
back and forth several times, and confirm that
the guide rod moves smoothly.
(8) Place the position where the head carriage
assembly pinches the stepper motor lead screw
at the center of the lead screw length.
(9) Place the mounting position of the guide rod
on the base so that the tail end of the guide rod
comes to the same position as the base or
projected less than 1mm.

(10)After remounting the above, adjust the radial
alignment according to the procedure in
section 9.6, adjust the track 00 sensor according
to the procedure in section 9.9.
Head carriage assembly
Fig.12-6.
The mounting position
of the guide rod
Guide rod L
The position
projected from the
baselessthan 1mm.
Removing the Head Carriage
Assembly, Rod Clamp,and Guide Rod
12.7 Removing and Remounting the Track 0
Assembly
(1) Remove the cover according to the procedure
in section 12.1.
(2) Remove the track 0 cable connector according
to the procedure in section 12.5.
(3) Remove the set screw on the track 0 assembly
and remove the track 0 assembly.
(4) Remount the track 0 assembly in the reverse
procedure of steps (1) to (3).
(5) After remounting track 0 assembly, adjust the
track 00 sensor according to the procedure in
9.9. ;
~
I [ i Track 0 Assembly
I ' I
I I j
I ..
. 11
Fig. 12-7. Removing Track 0 Assembly
- 17 -
12.8 Removing and Remounting the Stepper Motor
(1) Remove the cover according to the procedure
in section 12.1.
(2) Remove the stepper motor cable connector
according to the procedure in section 12.5.
(3) Remove the two set screws on the stepper
motor and remove the stepper motor.
(4) Remount the stepper motor in the reverse
procedure of steps (1) to {30).
(5) Ensure that the temporary fastened position of
the stepper motor is placed so that the two
projections on the base come to the centers of
the two long holes in the stepper motor
respectively.
(6) Apply* grease to the lead screw of the stepper
motor according to the procedures in steps (7)
and (8).
(7) Put grease in the size of a grain of rice on the
lead screw.
(8) Extend the grease over the lead screw evenly
using an applicator.
(9) After remounting the stepper motor, adjust the
radial alignment according to the procedure in
section 9.6, adjust the track 00 sensor according
to the procedure in section 9.9.
Note: Grease: MOL YKOTE EM-30L manufactured
by DOWCORNING.
Stepper Motor
Fig. 12-8. Removing the Stepper Motor