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Light path diagnostics
Light path diagnostics is a system of LEDs on various external and internal components of the server that
leads you to the failed component. When an error occurs, LEDs are lit on the front panel on the front of the
server and on the rear of the server, then on the failed component. By viewing the LEDs in a particular order,
you can often identify the source of the error.
• "Front panel" on page 21
• "External LCD diagnostics handset" on page 27
• "Rear view LEDs" on page 26
• "System board LEDs" on page 35
General problem determination procedures
Use the information in this section to resolve problems if the event log does not contain specific errors or the
server is inoperative.
If you are not sure about the cause of a problem and the power supplies are working correctly, complete the
following steps to attempt to resolve the problem:
1. Turn off the server.
2. Ensure that the server is cabled correctly.
3. Remove or disconnect the following devices, one at a time, until you find the failure. Turn on and
configure the server each time you remove or disconnect a device.
• Any external devices
• Surge-suppressor device (on the server)
• Printer, mouse, and non-Lenovo devices
• Each adapter
• Storage drives
• Memory modules until you reach the minimum configuration that is supported for the server
Note: The minimum configuration required for the server to start is one processor and one 8 GB DIMM.
4. Turn on the server.
If the problem is solved when you remove an adapter from the server, but the problem recurs when you
install the same adapter again, suspect the adapter. If the problem recurs when you replace the adapter with
a different one, try a different PCIe slot.
If the problem appears to be a networking problem and the server passes all system tests, suspect a network
cabling problem that is external to the server.
Resolving suspected power problems
Power problems can be difficult to solve. For example, a short circuit can exist anywhere on any of the power
distribution buses. Usually, a short circuit will cause the power subsystem to shut down because of an
overcurrent condition.
Complete the following steps to diagnose and resolve a suspected power problem.
Step 1.
Check the event log and resolve any errors related to the power.
Note: Start with the event log of the application that is managing the server. For more information
about event logs, see "Event logs" on page 207.
.
Chapter 5
Problem determination
209
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