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5.8.7
RADIAL ALIGNMENT OF HEAD
To radially align the head, use the following procedure:
A
Start motor and select disk drive.
B.
Insert an Alignment Disk. Alignment Disk should be at the same
environmental room conditions as drive for at least one hour before
alignment.
C.
Sync oscilloscope external positive with probe on TP5 and set
time base on oscilloscope to 20 milliseconds/division. This
provides a display of one diskette rotation.
D.
Set oscilloscope to measure differential signal between TP1 and TP2.
Ground probes, set inputs to AC, and set vertical deflection to 100
mi Ilivolts/division.
E.
Step to track 00. Insure that the following conditions both exist:
1. Phase A of stepper driver logic is active, 2. TP1 & 2 indicate a 2F data
pattern on the diskette. This will insure that the proper stepper motor
phase is active with the correct track number.
F.
Step disk drive to track 16.
G.
Loosen two mounting screws that hold stepper motor to main frame.
H.
Rotate stepper motor to move head radially in and out and observe cat eye
pattern on oscilloscope until the lobes are within 80% of each other, then
carefully lock down two previously loosened stepper motor mounting screws.
I.
Check adjustment by stepping off several tracks in both directions
from track 16 and return to track 16. If necessary, readjust by
5.8.8
repeating steps G and H, until cat eye pattern is within 80% of each other.
J.
After radial alignment of head is completed, track 00 switch and track 00/39
T
stop position must be checked and adjusted as required (see paragraph
5.8.4 & 5.8.5).
5.8.8
HEAD-LOAD BAI L ADJUSTMENT
To adjust the head-load bail, see Figure 5-5 and use the following procedure:
A.
Select disk drive and load head to energize head-load solenoid.
B.
Adjust two screws that hold diskette load arm and arm adjustment
bracket to head-load solenoid until 0.19
±
0.01-inch (0.4826
±
0.0254 cm) clearance is obtained between lower side of head-load bail
5-17
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