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If the pressure pad is worn to a point nearly even with
the surface of the head load arm, exchange the pad. Use
pad 81M (part 2200751).
Warning: The head area can be easily damaged or contami-
nated. Read the following before exchanging a pressure
pad:
•
Ensure that your tools are clean; use isopropyl alcohol
(part
2200200)
and a clean tissue (part
2162567),
or
use an alcohol pad (part
9900679).
• Do not touch the pressure pad with your fingers.
•
Be careful not to damage the new pressure pad or loosen
any of the pad's surface. The layer of adhesive on the
new pad is very thin; do not damage the adhesive. Do
not let the adhesive touch the surface of the pad that
will touch the diskette. Do not use damaged pads.
•
Do not scratch the head load arm.
• Do not let the head load arm hit the read/write head.
• Move the head load arm as little as possible. The ten-
sion spring,
0 '
can come out.
1.
Move the head load arm away from the read/write
head.
2.
Using your scissor clamp (part 9900233), pull the
worn pad off the arm.
3.
Carefully remove any adhesive that remains on the
arm.
4.
Ensure that the pressure pad mounting surface is
lint-free; use tissue (part 2162567) moistened with
isopropyl alcohol (part 2200200) or an alcohol pad
(part 9900679). If the surface is not completely
clean, the new pad may not seat correctly.
5.
Using a knife (or similar thin blade), lift off the paper
cover that protects the adhesive'layer on the new pad.
6.
Using your scissor clamp, carefully remove the new
pressure pad from the other new pads.
7.
Place the new pad in the center of its location on the
head load arm.
8.
Lightly press on the new pad with a clean screwdriver.
9.
Using the small end of the pressure pad tool,
e '
press at 90 degrees to the head load arm.
10.
Use your other hand to turn the tool at least one
revolution
in one direction only.
11.
Carefully move the head load arm back to its opera-
tional position.
12.
Test the read/write head output. See ReadIWrite
Principles (paragraph E.2.4).
E.3.2.2 Head/Carriage Service Check
See Figures E-23 and E-24.
Warning: The head/carriage service check must be per-
formed with the diskette drive installed (or with the disk-
ette drive in the same position as when installed) or the
adjustment might not be accurate.
1.
Power down.
I
DANGER
Voltage is still present at the socket when the
power cable is disconnected.
2.
Disconnect the ac drive motor power cable, • .
3.
Remove the head cable guide,
G .
4.
Turn the stepper motor pulley by hand to track
40, and insert a timing pin,
e.
(Ensure that the
pin goes into the casting.)
5.
Power up.
6.
To disable the stepper motor, install a jumper,
0 '
from TCP04 (ground) to TH05 (-'disable stepper
motor').
7.
To locate the stepper motor at track 40, install a
jumper,
e '
between TPF01 (ground) and
TPH04 (MC-O).
8.
Put the timing pin,
e '
through the stepper motor
pulley into the timing hole in the casting. Does the
timing pin pass freely through the hole?
y
N
Remove the timing pin,
e .
Remove the jumpers,
0
and
e .
Power down.
Go to the Head/Carriage Adjustment
(paragraph E.3.2.3), step 3.
9.
Remove the timing pin,
e .
10.
To move the stepper motor to track 39, remove the
jumper connected to TPH04 and install the jumper
end on TPH01 (MC-3).
11.
Verify that this is track 39 by visually checking for
no gap,
CD '
between the timing pointer,
e '
and
the timing block,
CD .
Appendix E. IBM 31SD Diskette Drive Maintenance
E-25
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