HP 7925D Service Manual page 89

7925
Troubleshooting
Replace PCA-A4.
Replace PCA-A3.
Load heads and unplug linear motor from
PCA-A9. Scope ATP
pas
on PCA-A5 and
observe runout. If peak-to-peak exceeds
2.QV, disc pack is defective.
NOTES:
1. Refer to the following diagram for circuit details.
• Head Positioning System Functional Diagram,
fig. 4-26.
2. PCA's associated with W. AR malfunction include:
• Servo PCA-A3.
• Drive control PCA-A4.
• Track follower PCA-AS.
No
No
Using the DSU, verify that track-to-track
seek time does not exceed 5 msec. If
necessary, perform velocity command
gain adjustment on servo PCA. Refer to
para. 3-11.
No
Replace PCA-A5.
No
Change pack.
No
Replace servo head.
7311-7C
Figure 4-5. W. AR LED Indicator Troubleshooting Flowchart
4-15