Product data

Chapter 2. Problem Determination Procedures
Are You Using the Correct Book? Do not use this book if you are servicing a 2104
Model DL1 or TL1. For the correct book, see Related Publications in Appendix A.
Additional Information for RISC Systems.
Problem determination procedures are provided by power-on self-tests (POSTs), service
request numbers, and maintenance analysis procedures (MAPs). Some of these
procedures use the service aids that are described in the user or maintenance
information for your using-system SCSI attachment.
Disk Drive Module Power-On Self-Tests (POSTs)
The disk drive module POSTs start each time the module is switched on, or when a
Send Diagnostic command is received. They check whether the disk drive module is
working correctly. The POSTs also help verify a repair after a Field Replaceable Unit
(FRU) has been exchanged.
The tests are POST-1 and POST-2.
POST-1 runs immediately after the ‘power-on reset’ line goes inactive, and before the
disk drive module motor starts. POST-1 includes tests of:
v Microprocessor
v ROM
v Checking circuits.
If POST-1 completes successfully, POST-2 is enabled.
If POST-1 fails, the disk drive module is not configured into the system.
POST-2 runs after the disk drive module motor has started. POST-2 includes tests of:
v Motor control
v Servo control
v Read and write on the diagnostic cylinder (repeated for all heads)
v Error checking and correction (ECC).
If POST-2 completes successfully, the disk drive module is ready for use with the
system.
If POST-2 fails, the disk drive module is not configured into the system.
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