IBM 7133 D40, Service Manual

Page: 91 / 306

Chapter 2. Problem Determination Procedures
Are You Using the Correct Book? Do not use this book if you are servicing a 7133
Model 010, 020, 500, or 600 SSA Disk Subsystem. For the correct book, see Related
Publications in the “Additional Information” appendix (in this book) for your using
system.
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 SSA 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 from the SSA attachment. They check whether
the disk drive module is working correctly. The POSTs also help verify a repair after a
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
Safety circuits.
If POST-1 completes successfully, POST-2 is enabled.
If POST-1 fails, the disk drive module Check light stays on, and the disk drive module is
not configured into the SSA network.
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.
73