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C.
With door closed, remove E-ring (item 8) from clutch shaft (item 2)
on carrier (item 1).
D.
Open door and carefully remove entire clutch assembly, with clutch
spring (item 9) from disk drive.
E.
Carefully place new clutch assembly, with clutch spring onto the
spindle hub on disk drive.
F.
Slowly close door to compress clutch spring and allow clutch shaft
to protrude through hole in carrier.
G.
Reinstall E-ring onto clutch shaft. No adjustment required.
5.7
HEAD AMPLITUDE CHECK
The head amplitude check is valid only when reading previously written data. The diskette used for
this check should show no evidence of wear or damage on either side. Use the following procedure:
A.
Install known good diskette.
B.
Start motor.
C.
Select disk drive and step to track 34.
D.
Sync oscilloscope external on TP5 (+Index). Set oscilloscope
to measure differential signal between TP1 and TP2. Ground probes.
E.
Set volts-per-division to 50 millivolts and timebase to 20 milliseconds
per division.
F.
Write entire track with all one's.
G.
Measure read-back head amplitude. Average minimum read-back
head amplitude should be 200 millivolts peak-to-peak.
H.
Check motor speed (see paragraphs 5.8.1-5.8.2).
I.
If output from disk drive PWB looks inappropriate, change main
disk drive PWB and recheck.
J.
Check head load pad for wear which would cause soft failure mode, i.e.,
slight gap between head and pad. This can be checked by very lightly
touching the top of the head load arm and checking to see if the signal
as observed on the scope increases. (See paragraph 5.8.3 for adjustment.
K.
If steps H-J check out but average minimum read-back head amplitude
remains low, the head and carriage assembly must be replaced.
5-11
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