Mitsubishi M4853 User manual

....
-,
TJ2-4861A
5.25 INCH FLEXIBLE DISK DRIVE
MODEL M4853
MAINTENANCE MANUAL
MITSUBISHI ELECTRIC CO., LTD.

4. OPERATING IHFOR.."' .. '\TlON
4.1 Environment
There
is no problem in operating under normal office conditions
but
when operating out of following conditions, Drive may not
work properly or Diskette may get damaged.
1 Temperature/Humidity Range
Durino Operatio~
Quring Nbn-ooeration
Temperature
Range +5°C - +43°C
Humi d ity Range
20~ - 80~ RH
(DEW LESS)
5: -95: RH
(DEW LESS)
(Maximum wet bulb temp 29.4°C)
• During Transportation
Tempe,ra ture Range -40
Cl
C - +62
C1
C for maximum ped od of 72 hours
Humidity
Range
1% - 95% RH with no
peri odof 72 hours condensation
for m~ximum
Z Dust
Be extra careful of dust entering unit because it may
damage to head or diskette media. cause
4.2
Diskette Handling
(Be extra careful of the following)
1
Keep diskette media away from any applian~e which may generate
magnetic
field. (i.e. radio, tv, motor/dynamo and other
electrical appliances.)
2 Do not bring any ferro magnetic materials near the diskette ..
3 Do not bend media under any condition.
4 Return the diskette
storing it.
to storage envelope when transporting and
S Do not touch
alcohol.
or attempt to clean the disk media surface with
6
Do not expose diskette to head, d~st or sunliyht.
7 Do not write anywhere
a
soft felt tip pen. except
on the medial label and only use

FICLIRE 2
-3-

5. REGUlAR MAINTENANCE
"Unit life can be affected by damaged parts as a result of dusty
environment
or excessive operation". So maintenance by such
methods as visual
inspection, cleaning/change of damaged parts
and regular functional checks will keep the unit in good condition
and enable the discovery of any problem at an early stage.
Time span between maintenance is calculated at an actual operation
rate of 8 hours a day so in case of a greater rate, differences
modification is needed. When operating at a normal environment
condition, perform mairtenance onc~ a year.
5.1 Caution
1 During maintenance,
be careful of dust entering unit, and
damaging head.
2 Make sure power sl/itch ;s off first when starting maintenance.
3
When put off/on P-inted Circ~it Board (P.C.B.) Assy, make
sure power switch is "off" to protect semiconductors and ICs.
4
Do not touch Ois~ media surface or head directly and do not
bring
any ferro n~gnetic materials near it.
5 When using this unit for Read data only (when using CE disk),
be careful of write mode ~ishandling to protect data.
6 Do not touch steEl belt and do not adjust related mechanism.
7
Avoid static shock or excessive force to head carriage assembly
because
it has bE-en ca refull y adjusted. Do no readjust any
screws except wh(re
specified in this manual.
-4-

5.2 Head Cleaning on Field Applications
Head cleaning is recommended at user's sites, especially when used
in severe environments, because the heads may accumulate dust in
the
air and mag~etic coating material of the disk, causing chance
of error increase and/or scratch on the disk surface.
Recommended sch:?dules and procedures are as follows:
1) Cleaning Schedules
(1) Periodical cleaning using
wet type cleaning disk.
i. Once a mrnth for normal usage in normal
environments.
ii. Should be increased to about once a week when
used in severe environments such as dusty area,
high humidity, high and low extreme temperatures.
Low temperature such as 5 to 10°C (41 to 50°F)
under
hi~h humidity is most severe for diskettes.
iii. Higher frequency for brand new drives would be
recommended. for about once a week. Better
matchnirg between head and medium would be produced
by a 10119 time use, as experienced.
(2)
When frequent errors are detected. (Wet or dry type may
be Jsed.)
(3) Whe.l scratch(es) are found on the medium surface. (Wet
or dry type may be used.)
2) Recommended Head Cleaning Material
(1) Wet type
Innovative
Computer Products*, Head Cleaning Kit (or
equivalent).
*18360 Oxnard Street, Tarzana. California 91356
[phone]/TWX 910-493-5964
(2)
Dr} type
To be supplied by Mitsubishi representatives. No
substitutions would be allowable unless accepted by
fartory test.

5.3 Check and Adjustments
5.3.1 Diskette
rotational cycle adjustments
1) Equipment
CE Tester (Disk Exerciser)
Scratch Diskette
Universal Counter
VR Adjustment Driver (Pot Trimmer)
2) Adjustment procedure
2)-1 Connect
CE Tester to Drive then turn-on. power switch.
2)-2
Load diskette then turn-on motor with drive select.
2)-3 Make sure HLMG ON. (Head Loaded)
2)-4 Seek to TKOO.
2)-5 Connect universal counter to+INDEX (interface signal)
and measure rotational cycle rate.
2)-6 Adjust counter reading until it comes within
specifications using SPM VR (see Figure 4).
2)-7 After this adjustment, Lock VR with white paint.
3) Test specification
3)-1 Check: ±1.6% (196.8 -203.2ms)
3)-2 Adjust:
±1.0% (198.0 -202.0ms)

'.
"
r , "
.#- , -,'
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....... '. ..
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- .. '"- ~ ..
198.0 ... 202.0
" I'
r
...
+INOEX
FfGURE 4
-7-

5.3.2 TKOO sensor position adjustment
1) Equi pment
CE Tester (Disk Exerciser)
Scratch Diskette
No. 1 plus screw driver
Oscilloscope
2) Adjustment procedure
2)-1 Connect CE Tester to Drive then turn-on power switch
and load diskette.
2)-2 Turn-on motor
and select
drive.
2)-3
Repeat seek between TKOO and 02
(see Figure 5).
2)-4 Observe
waveform (TKOO) at TPBl
using oscilloscope.
tr;gger CHl--step (DC, +) TPD15
signal CH2--TKOO (DC
) TPEl
2)-5
Loosen screw and adjust time
until it comes to
within 3-4ms by moving TKOO in
the direction of
the arrow (see
figure).
3)
Note:
3)-1 Set step
rate at 3ms using CE tester.
3)-2 Make sure there are 2 pulses on step signals.
5.3.3 TROO Sensor Check (Alternate Procedure--recommended)
Connect disk exerciser to drive
Turn on motor and Select drive
Insert Diskette
Recalibrate (Seek) to TROO
Connect oscilloscope probe channel I/DC to TPBl
Trigger Mode Auto
Source CHI
2 volts/Div
± lmsec./Div
TPBl should be high at TKOO
Step out to TK02
TPBl should be low .
-8-

-'.
.
Trigger (CH1) 2-1-.0
TK TK
(k-1-2
t 11 11 ~
1 I.· (3ms)
·I~_--...I---
.,
3-4ms
FIGURE 5

5.3.3 INDEX sensor position adjustment
1) Equipment
CE Tester
CE diskette (DYMEK 502-10 STANDARD DISKETTE)
No. 1 plus screw driver
Oscilloscope
2) Check procedure
2)-1 Connect
CE Tester to Drive (set power off).
2)-2 Turn-on power switch and motor on.
2)-3 Select drive and load CE diskette (close clamp door
slowly) .
2)-4
Read timing of each waveform at TPB9 + TPBIOunder
read
model'TK02, using oscilloscope. (See figure.)
Trigger:
EXT - +INDEX (DC, +) (TPD14)
Signal:
CHI - TPB9 (AC) lOOrn\t/Div
CH2 - TPBIO (AC,INV) Add SO-"(s/Div
2)-5
Specification
Check:
200±200 ~s at TK02
Sici~ n
200 ± 30 0 -"'( sat TK 02
Siee 1
Adjust: 200±100 ~s at TK02
Side 0
LUO±200
~s at TK02
Side 1
*Check = make sure reading falls within this spec.
Adjust = if reading is out of ~check~ spec., adjust
to within spec. indicated here.
Tric;c;er
r
fINOEX
(TPD14)
(SOus)
Signal
(TPB9+10)
\~urs'!;
waveforal.)
•
•
To2
FIGURE 6
PCA. set screw

5.~.4 Head alignment adjustment
1) Equi pment
CE Tester
CE Diskette (DYMEK 502-10 STANDARD DISKETTE)
No. 1 screw driver
Oscilloscope
Hex wrench (1.5mm dia.)
2) Adjustment procedure
2)-1
Connect CE Tester to Drive (set power off).
2)-2 Turn-on power switch and motor on.
2)-3 Select drive
and load CE diskette (close clamp door
s1
owl y).
2)-4 Seek TKOO to TK32 then read amplitude of each
waveform (positioning waveform) at TPA1+ TPA2
under read mode (see Figure 7).
Trigger:
EXT - +INDEX (DC. +) (TPD14)
Signal:
CHI -TPB9 (AC ) Add 100rn\l!Div
CH2 -TPBl.O (AC.INV) 20 ms/Div
Specification:
whenA>B B/A > 60%
A<B A/B > 60%
2)-6 Seek both directions TKOO-tTK32i'm~TK79""'K32.
loosen both set screws, then adjust STM until
Signal comes within spec. Tighten screw.
3) Note: Adjust ~nder following conditions
Temperature:
23°C ±2°C exposed over 2 hours
Humidity:
50% ±5%
-11-

FIGURE 7
-12-

5.3.5 Head Azimuth
I) Equi pment
CE Tester
CE Diskette
Oscilloscope
2) Check procedure
2)-1 Connect
CE Tester to Drive then turn-on power switch.
2)-2
Turn on motor.
2}-3
Select drive and load CE diskette.
2)-4 Seek to TK68.
2)-5 Read azimuth waveform using oscilloscope.
Trigger:
EXT - +INDEX (DC +)
(TPD14)
Signal:
CHI -TPB9 . (AC) Add lOOm~/D~v
CH2 -TPBIC (AC,INV) ± Ims/DJ.v
2}-6 Acceptable when adjusted waveform within following
range
FIGURE 8
TPD14
____ ~r--l~ ____________________________ _
(INDEX)
0' Azimuth "Error
TPB9/TPBIO
----------~I_AJ~. ~1,B I~!.C'!~.! D:~. ------
(USE DIFFERENTIAL AMP) --J __
AZIMUTH
~±18'
115>AX
115 ~ ~ X 100
~ X 100 ~ 115
(-18I ) (+
18 I )
Note: A=B: -12min
Specification= ±18min
C=D: +12min
, .,

•
NOTE
The head's azimuth is not adjustable. It is suggested that the drive be
sent to an authorized repair center or a new head assembly be installed.
In the latter case, all previous adjustments should be made again.
-14-

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