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C141-E166 6-15
6.4.3 Troubleshooting at the repair site
For maintenance at this level, we recommend additional testing of the disk drive and signal
checking.
The sense data posted from the IDD helps with troubleshooting. This sense data makes the error type
clear (functional, mechanical, or electrical error). Chapter 7 error analysis by sense data, and gives
supplementary information on finding the error cause (faulty part).
Table 6.3 lists how to detect a faulty disk drive subassembly. This fault finding requires a working
host computer or disk drive test equipment to recreate the error conditions.
If the detected error cannot be recreated in an ordinary test, disk drive conditions can be changed
to force the error to recur. This is done by changing the DC voltage or the ambient temperature of
the disk drive.
If the error does not recur with changed conditions, the disk drive is not faulty. If no error occurs
in the disk drive test, notify the user of the test results, and find out from the user the environment
conditions where the disk drive is used.
Table 6.3 Disk drive troubleshooting
Item Recommended action
Frequent or repeated seek errors Collect sense data, and see Chapter 7.
Replace the disk drive, and check that the test method is correct. If the
error recurs, it is likely that the disk drive is normal but the test method
is incorrect.
Intermittent or nonfatal errors Replace the disk drive, and check that the test method is correct. If the
error recurs, it is likely that the disk drive is normal but the test method
is incorrect.
To check performance, change the disk drive conditions by changing
the voltage or temperature.
If the disk drive error recurs or a possibly faulty part is found by troubleshooting, return the
complete disk drive to the factory for repair. A media defect list must be included with a disk
drive returned to the factory.
If the possibly faulty part is the disk enclosure, return the whole disk drive to the factory for repair.
Also if a clear error (erroneous servo track information or noisy drive) is detected in the disk
enclosure, return the whole disk drive to the factory. A media defect list must be included with a
disk drive returned to the factory.
CAUTION
Damage
Never open the disk enclosure in the field. Opening the disk
enclosure may cause an irreparable fault.