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Table 2.1 System-level field troubleshooting
Item Recommended work
AC and DC power level Check that the DC voltage is within the specified range (±5%).
Check that the +5 VDC value (pin of the interface connector) is 4.75 to
5.25 VDC.
Check that the +12 VDC supply (pin of the interface connector of disk
drive) is 11.4 to 12.6 VDC.
Electrical noise Make sure the maximum ripple peak-to-peak value of +5 VDC is
within 250 mV and +12 VDC is within 250 mV.
Drive selection address Check that the disk drive selection address is set correctly.
System cables Check that all system cables are connected correctly.
System diagnostic test When possible, execute the system level diagnostic routine as explained
in the host computer manual. This gives a detailed report of a possible
fault.
Intermittent or nonfatal errors Check the AC voltage from the power supply. Check the DC voltage
level at the power connector for the disk drive.
If the AC voltage level is abnormal or there is a lot of electrical noise,
notify the user of the error.
If the DC voltage level is unstable, replace the power supply unit.
If possible, replace the disk drive. If replacing the disk drive does not
eliminate the error, the removed disk drive is probably not faulty. To
continue error analysis, refer to the hardware and software manuals
supplied with the system.
2.3.3 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 3 error analysis by sense data, and gives
supplementary information on finding the error cause (faulty part).
Table 2.2 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.