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3.2. 17 Read/Write Head
To adjust the read/write head, you must obtain
three simultaneous conditions:
• Correct clearance from head to CE tool.
• Correct relationship between the stepper
motor wheel and leadscrew wheel.
• Correct clearance between the stepper motor
and leadscrew wheels.
Adjustment
This adjustment procedure aligns the read/write
head at track 00.
1.
Turn power off at the operator control
panel and remove the 33FD from the
machine (3.2.5).
2.
Remove covers (3.2.8). Remove the leadscrew
dust cover (if installed) (3.2.10.1).
3.
Rotate the stepper motor wheel until the
head carriage is against the lower stop.
4.
Loosen the mounting screw and move the
phototransistor assembly
rl
to the left.
Note:
If phototransistor assembly is not
moved, the accuracy of the head adjust-
ment might be affected.
5.
Loosen the clamping screws on the lower
limit stop
m
and leadscrew wheel
D .
6.
With the stepper motor wheel and leadscrew
wheel oriented as in view
II,
insert 0.020
inch (0.508 mm) feeler gauge between the
wheels as shown by
D
in view
m.
Slight-
ly tighten screw
D .
Note:
The purpose of this step is to
provide maximum stepper motor wheel
to leadscrew wheel pin penetration with
no binds.
7.
8.
9.
10.
Locate the white dot label or the inden-
tation on the outer circumference of the
hub. If hub has bqth, always use white
dot. Rotate hub to position this mark
180 degrees away from the read/write
head.
Note:
This ensures that any hub eccen-
tricity is located in the same spot and that
all head adjustments use the same refer-
ence point.
CAUTION
Avoid any contact of CE tool with highly
polished surface of head.
Install CE tool on hub
m .
Clamp into
place with thumbscrew and rotate CE tool
so it contacts surface
m .
Rotate leadscrew by gripping upper limit
stop
II ;
adjust for gap
II .
This gap
is a number found on the front of the
head assembly
II .
This number repre-
sents thousandths. Example: 3 equals
0.003 inch (0.076 mm). Adjust for a
very light drag on a 0.003 inch (0.076 mm)
gauge. A 0.002 inch (0.051 mm) gauge
must be free.
Note:
Remove the feeler gauge from the
pack to make this adjustment.
Make sure the stepper motor wheel and
leadscrew wheel remain oriented as in
m ;
then securely tighten the leadscrew
wheel clamping screw
D.
The top of
the clamping collar should be approxi-
mately even with the top of the metal
clamping surface of the leadscrew wheel.
CAUTION
If the clamping collar is not securely
tightened, machine operation causes the
head to go out of adjustment.
3-18
TNL: SN31-0487 to SY31-0373-4 (25 Nov 77)
11.
Recheck gap
IJ
setting.
12.
Adjust the phototransistor
a
so that
the raised edge is in contact with CE tool
13 ,
and tighten the mounting screw.
13.
Remove CE tool and perform lower limit
stop adjustment (3.2.19).
14.
Rotate stepper motor wheel at least one
full revolution and check for binds.
15.
Do upper limit stop adjustment (3.2.20).
16.
If a new leadscrew wheel was installed,
the slot should be 25% to 40% full with .
IBM No. 23 grease.
17.
Replace covers. Replace the leadscrew dust
cover (if previously removed) (3.2.10.1).
18.
Install the 33FD in the machine (3.2.5).
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