IBM 5280 Maintenance Information Manual page 132

Page of SY31-0602-o
As updated 5 June 1981
By TN L SN20-9529
339
HEAD/CARRIAGE ADJUSTMENT
CAUTION
The head/carriage assembly adjustment must be performed
with the diskette drive installed (or in the same position as
when installed) or the adjustment might not be accurate.
Note: This procedure should not be performed unless para-
graphs 363 and 337 have been completed or you were di-
rected to this procedure from another manual.
11.
Go to 361, step 1.
DANGER
Capacitor discharge voltage might be present at the
socket when the AC drive motor power cable is
disconnected.
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2. Measure and record the gapllbetween the stepper
motor pulley and the casting. The gap is _ _ _
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3. Loosen the clamp screwllso the stepper motor
shaft can turn inside the pulley.
4. Move the stepper motor pulley to track 40 by
carefully moving the head carriage assembly and
inserting the timing pin.
5.
6.
Power on.
Set the gap
II
to the same size as the gap recorded in
step 2 and tighten the clamp screw. (Ensure that the
timing pin passes freely through the stepper motor
pulley into the timing hole in the casting and that
the clamp
II
is positioned 1
±
0.25 milimeters
(.040
±
.010 inches) as shown.)
12 Head/Carriage Assembly
7. Remove the timing pin.
8. Loosen the two screws
1m
that hold the bracket to
the carriage.
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9. Remove the jumper end from
II;
and momentarily
touch it to
a.
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10. Reinstall the jumper end on
II.
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Note: Steps 8 and 9 set up the required torque condition
of the stepper motor for the following steps.
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11. Verify that the stepper motor pulley is at track 40 by
visually checking that the timing ho!e in the pulley is
aligned with the timing hole in the casting. Use a
dental mirror to check. Do not insert a timing pin.
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12. Insert thickness gauges
1m
totaling 0.508 millimeters
(0.020 inch) between the timing pointer on the .
carriage and the track 40 adjustment surface on the
casting. Clamp the thickness gauge
1m
to the casting
with the retaining clipll]provided (part 4240632).
The clip is attached to the diskette guide. (For
location, see 330
1m.)
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13. Slide the head/carriage assembly against the thickness
gauge so it just touches but is not forced against the
thickness gauge. I nsert the carriage pressure spring
III
(part 4240631) between the casti ng and the
carriage to hold the carriage against the thickness
gauge. The carriage pressure spring is attached to the
diskette guide. (For location, see 330
1m.)
14. Tighten the two screws that hold the bracket to the
carriage
Ill.
15. Remove the retaining clip and the carriage pressure
spring.
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16. Go to 337 step 20.
~-~""-------r? ~
~
ol-.-L
1 to.2S
mm
• . t
(.040
±
.010 inch)
339