Panasonic Ju4755 Service Manual

Panasonic 
ORDER NO. M SD 85090 2900 
Flexible  Disk Storage  Drive 
,,,U-455-5 
Matsushita Communication 
Industrial Co., Ltd. 
Memory 
Systems Division 
3- 1,  4-cho me, T sun ashima-Higas hi 
Ko h
oku-ku,  Yokohama 223 JAPAN  

CONTENTS 
PART I 
1. INTRODUCTION -..•.••.••...••..•••.••.....••.\
•..•..........•....•••••...••..•....•............•. ....•..•••..••....•.••.•.••.•. 
2 . MOD ELS AND M DOOE L NUM BERS ............................................................................................ . 
3. SPECIAL TOOlS···························· ····················· .................................................................... . 
4. 
5. 
•• 
7. 
•• g . 
10 . 
11. 
O UTLIN E OF MAINTEN AN CE...

r 
r 
PART. I 
1. INTRODUCTION 
This service manual consists  of two parts , Part I covering mainten

4. OUTLINE OF MAINTENANCE 
• The following tools ate  required for maintenance of a Floppy  Disk Drive. (FOO) 
4.1  Alignment Diskette 
Alignment diskette is used for nead actuator al ignment and  index  sensor  adjustment  . 
• Ad;tiuments (Refer  to table 8.1) 
(1) Specify an appIJcable  mode l from label 8.1. CInd make  a readlwrite head radial adjustment at  a specified tracle. 
(SidesQ,l) 
(2) Make an iod ell timing adjustment at a specified Irack . (Sides O. 1) 
(3) 
Make iHI azimuth measurement at...

5.3 Write Error 
If an error occurs during  write operation, it is usua lly detected during  the next revolution by perform ing a read opera· 
tion ca lled wr ite check. To correct an error, write again and repeat a  write  check operation. If the result is unsatis ­
factory after te n  or  more  write  operations , perform  a read  operation on another track to determine whether it is the 
diskette o r the drive that is wrong . If an error persists , rep lace the diskette and repeat the above procedure....

6.2 Trouble Shooting Flow Chart 
S TART 
- 4  -
Set Addru. SW 10 Track  

6.3 Trouble Analysis Table Table  6.1 
It em  Troubl
e No. Cause S.2S·jndi JU-3x 3 ,.. JU-3x2 
1 Index detection 1 Collet art fault R. lace , , 
failure 2 DO motor (Ontlol PCB ~~eploce Replace DO motor. Rep lace 00 motor 
~liIpllM':e:  ::~:: Base assembly assemblV 3 DO motor faulty 
4 Index  LEO faultv f:Il!pl;, 
-2  Not ready 1 S
ee Item 1. ? .... 
2 PCB ready circuit Rep~ir .  *, -
,;, -3 Track  0 detection 1 Track 00 a~5embly :,.AeplltC!I !!i 
-
if. 
-failure 2 PCB  Irack  0 detection failure...

8. MEASUREMENT ITEMS FOR EACH MODEL 
Table 8 .1 
•• m Parameter JU- 3 12,313,314 JU·32X,36X JU -581,S85 
TRK Value TRK Val ue TRK Value 
1 Index period 20 200t3ms 40 200 ± 3ms 32 166.7 ;!; 0.2 m5 
2 Output level 39 16OmVor 7 180mVor 76 120mVor more more  more 
, Radial Alignment 20 75 40 50% 32 70% 
4 AZIMUTH 20 ± 18 40 ± 18 68 ± 18 
5 Index burst 20 3±1.5ms 40 3±1.5ms 68 200t 200 III 
6 FLAG 0 From track 1 ;1 From track 1 1: 1 From track 2 
1: 1 totTack 2 totra,k 2  totTack3 and back and back. and back...

9. ADJUSTMENTS  AND VERIFICATIONS 
9.1  Motor  Speed Adjustment and Confirmation !Index Period) 
(1} Insert a diskette,  run the motor, and damp, Refer to the index  period column of Table 8 .1  for the applicable 
model . 
(2) Step to the  specified  track . 
(3) Connect a  frequency  counter to the INDEX signal. 
. 5.25,-inch : TP7 
3.5·inch:  IX 
(4 )  Check  th at  the  frequency counter rea dings meet the specifications  in th e table . 
(5 ) Adjuument 
5.25 -inch: Turn  th e speed control...

9.4 Output Modulation Verification 
Modulation: M is calculated by the following  formula. 
Vmax-Vmin 
M(%) .. )(100 using t h e va lue obtained in 9 .3 , and check that the 
Vma)(+Vmin 
calculated  value 
is 20% or less . 
_____ _ _____ ~~;:::~:.::i2====Mal(imum Voltage  Valve: Vma)( -------~----~----- 7% Average Voltage Minimum Voltage Valve: Vm ax 
Fig.  9.1 Modulation 
9.5 Radial  Alignment  Adjustment 
Introduction 
This adjustment Is  normally not necessary . 
rf the mounting  screws for the...