Oracle Sun Server X4-4, Service Manual

Page: 53 / 292

Troubleshoot Hardware Faults
Troubleshooting and Diagnostics 53
Power Supplies (PSUs)
The server power supplies (PSUs) provide the necessary server voltages from the AC power
outlets. If the PSUs are inoperable, unplugged, or disengaged from the internal connectors, the
server cannot power on.
Action
: Check that the AC cables are connected to both PSUs and that the PSUs are operational
(the PSU indicator panel should have a lit green AC OK indicator). If not, ensure that the PSU
is properly installed. A PSU that is not fully engaged with its internal connector does not have
power applied and does not have a lit green AC OK indicator.
Prevention
: When a power supply fails, replace it immediately. To ensure redundancy, the
server has two PSUs. This redundant configuration prevents server downtime, or an unexpected
shutdown, due to a failed PSU. The redundancy allows the server to continue to operate if one
of the PSUs fails. However, when a server is being powered by a single PSU, the redundancy
no longer exists, and the risk for downtime or an unexpected shutdown increases. When
installing a power supply, ensure that it is fully seated and engaged with its connector inside the
drive bay. A properly installed PSU has a lit green AC OK indicator.