3-20. On-Line Checkout - HP 7925D Service Manual

7925
g. Press the START pushbutton and wait for the
5-second cycle to complete. The display and meter
should read the same as that given in step f.
h. Repeat steps c through g for each data head to be
aligned, using the binary combination of toggle
switches H8, H4, H2, and HI.
i. Set the FUNCTION switch to position 3, rotate the
DELAY control to a position near MIN, and press the
START pushbutton. Allow the disc drive to random
seek for 2 minutes.
j.
Verify that head alignment is within a reading of 0.0
±2 on the HEAD ALIGNMENT meter.
k. If a head is out of tolerance, repeat steps e through j.
1. Repeat steps i and j for each data head.
m. Read the temperature of the disc drive from the liquid
crystal thermometer (see figure 3-6) and record this
temperature on the head alignment label.
Alignment and Adjustment
Note: The disc drive temperature is read by
noting the number containing a green
color on the liquid crystal thermometer.
If only blue or brown colors show, the
disc drive temperature is the average of
the blue and brown numbers.
This number represents the disc drive
temperature in degrees Celsius. For
proper operation, the disc drive tempera-
ture should be within ±10°C (±18°F) of
the temperature recorded on the head
alignment label (located inside of the
front door).
n. Perform the circumferential alignment check.
3-20. ON-LINE CHECKOUT
When all adjustments have been completed, remove the
CE disc pack. Set the DISC switch on the operator panel
and the circuit breaker on the power panel assembly to the
OFF positions. Remove the DSU, head alignment PCA,
and related cabling. Reconnect the cabling disconnected
prior to alignment, replace the shroud, and apply ac
power. Perform an on-line checkout in accordance with
diagnostic tests supplied with the system.
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