6.4.3Troubleshooting 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 | |
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Item |
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| Recommended action |
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Frequent or repeated seek errors |
| Collect sense data, and see Chapter 7. | |
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| Replace the disk drive, and check that the test method is correct. If the | |
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| error recurs, it is likely that the disk drive is normal but the test method | |
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| is incorrect. | |
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Intermittent or nonfatal errors |
| Replace the disk drive, and check that the test method is correct. If the | |
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| error recurs, it is likely that the disk drive is normal but the test method | |
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| is incorrect. | |
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| To check performance, change the disk drive conditions by changing | |
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| the voltage or temperature. | |
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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.
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