Power Supply Troubleshooting - Sun Microsystems Ultra 80 Service Manual

Note – To bypass POST, type
At the system ok prompt:
ok reset-all
ok probe-scsi
If the hard drive responds correctly to probe-scsi, the message identified in
CODE EXAMPLE 4-4
successfully probed the devices. This is an indication that the motherboard is
operating correctly. If one drive does not respond to the SCSI controller probe but
the other does, replace the unresponsive drive. If one hard drive is configured with
the system and the probe-scsi test fails to show the device in the message, replace
the drive. If replacing the hard drive does not correct the problem, replace the
motherboard.
4.5

Power Supply Troubleshooting

Caution – This procedure must be performed by a qualified service-trained
maintenance provider. Persons who remove any of the outer panels to access this
equipment must observe all safety precautions and comply with skill level
requirements, certification, and all applicable local and national laws.
Caution – During the power supply voltage measurement checks, an operational
load must be on the power supply. Ensure that the power supply cables remain
connected to the motherboard.
The section describes how to test the power supply when under an operational load
using a DVM. See the figures and tables that follow to identify the J4106 and J4107
power connectors.
1. Power off the system and remove the access panel.
See Section 6.1 "Powering Off the System/Removing the Access Panel" on page 6-1.
-6 Sun Ultra 80 Service Manual • March 2000
setenv diag-switch? false
on page 4-12 is displayed; the system SCSI controller has
at the ok prompt.