Digital Equipment RW504-ZA, Service Manual

Page: 69 / 220

4.5.1 The Autochanger Lists the First ‘‘Possibles’’
At power-on, and after every failed move, the autochanger automatically runs
an initialization sequence that comprehensively tests the autochanger. If a hard
failure occurs, a list of possible FRUs that may have been at fault is returned.
Keep in mind that these FRUs are not listed in any prioritized manner. You
should visually inspect to determine the most likely candidate.
Figure 4–2 The Autochanger Returns Suspect FRUs
Note
This test sequence returns possible failed FRUs only if there has been
a HARD FAILURE. The test sequence will NOT find an intermittent
failure. This test sequence, called the ‘‘FRU Isolation Test’’ (test 60), can
also be run from the control panel. Similar to its automatic operation,
this test sequence only points out (‘‘isolates’’) FRUs if there has been a
hard failure.
What the Autochanger Assumes –
The FRU Isolation Test assumes the following:
• There was a failure.
• The cause of the failure was physical (either mechanical or in the electronics).
Troubleshooting and Diagnostics 4–11