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Diagnostics and Maintenance
6.3
Operation Check
6.3.1
Initial seek operation check
If an error is detected during initialization by the initial seek operation check routine at power-on, the
IDD sends the Fault LED Out signal to the interface connector. The spindle motor of the disk drive
then stops, and the disk drive is unusable.
For an explanation of the operation check before the initial seek, refer to the Section 5.5.
6.3.2
Operation test
While the host computer is processing data, the IDD monitors disk drive operation including data
processing, command processing, and seek operations. If the IDD detects an error, the IDD posts the
error to the INIT. The INIT then posts the error to the user.
The user may detect an intermittent or nonfatal error such as abnormal noise, abnormal odor, or very
slow operation.
An error posted in an operation test must be investigated. Replace the disk drive to see whether the
error was caused by the disk drive.
Often, errors posted in an operation test may be caused by the host system. Possible causes include
insufficient power capacity, loose cable connection, insufficient timing or insufficient mechanical
play, and problems related to other systems.
If an operation error is detected by the error detection circuit of the disk drive, an interrupt occurs.
The interrupt is posted to the MCU on the PCA. The MCU stops the currently processed command,
and causes the CHECK CONDITION status to post the error to the INIT.
When receiving the CHECK CONDITION status, the INIT issues a REQUEST SENSE command to
collect detailed information about the error. The INIT then issues a REZERO UNIT command to
return the read/write head to track 00. In normal processing, the IDD itself or INIT determines how
to handle the error (processing retry or stop).
To analyze the error posted in the operation test, reconstruct the conditions in which the error
occurred. Then, start troubleshooting the whole host system by replacing the disk drive.
6.3.3
Diagnostic test
The diagnostic test is executed to find a faulty subassembly in a faulty disk drive, or to check disk
drive performance. This test is usually a combination of specific disk drive functions or group of
functions. This test may be executed using a different host computers or test equipment and away
from the environment where the error first occurred.
To analyze the error posted in the diagnostic test, reconstruct the conditions in which the error
occurred. Then, look for a possibly faulty subassembly or part of the disk drive.
The procedures to be used in this test depend largely on the type of test equipment used, and are not
covered by this manual.
6-12
C141-E198
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Table of Contents
Troubleshooting
