Lenovo ThinkServer RD120 Hardware Maintenance Manual page 211

Attention: In a dc power environment, only trained service personnel other
than Lenovo service technicians are authorized to connect or disconnect power
to the dc power supply. See the documentation that comes with each dc power
supply.
2. Check for loose cables in the power subsystem. Also check for short circuits, for
example, if a loose screw is causing a short circuit on a circuit board.
3. If a power-channel error LED on the system board is lit, perform the following
steps; otherwise, go to step 4. See "System-board LEDs" on page 15 for the
location of the power-channel error LEDs. Table 21 identifies the components
associated with each power channel, and the order in which to troubleshoot the
components.
a. Disconnect the cables and power cords to all internal and external devices.
Leave the power-supply cords connected.
Attention: In a dc power environment, only trained service personnel
other than Lenovo service technicians are authorized to connect or
disconnect power to the dc power supply. See the documentation that
comes with each dc power supply.
b. Remove each component that is associated with the LED, one at a time, in
the sequence indicated in Table 21, restarting the server each time, until the
cause of the overcurrent condition is identified.
Important: Only a trained service technician should remove or replace a
FRU, such as a microprocessor or the system board. See Chapter 3, "Parts
listing, ThinkServer RD120 Machine Types 6444, 6445, 6446, and 6447," on
page 25 to determine whether a component is a FRU.
Table 21. Components associated with power-channel error LEDs
Power-channel
error LED
A
B
C
D
c. Replace the identified component.
4. Remove the adapters and disconnect the cables and power cords to all internal
and external devices until the server is at the minimum configuration that is
required for the server to start (see "Solving undetermined problems" on page
194 for the minimum configuration).
5. Reconnect all power cords and turn on the server.
Attention: In a dc power environment, only trained service personnel other
than Lenovo service technicians are authorized to connect or disconnect power
to the dc power supply. See the documentation that comes with each dc power
supply.
If the server starts successfully, replace the adapters and devices one at a time
until the problem is isolated.
If the server does not start from the minimum configuration, replace the components
in the minimum configuration one at a time until the problem is isolated.
Components
Fan 4, fan 6, fan 8, fan 9, microprocessor 1, system board
(integrated voltage regulator)
Fan 1, fan 2, fan 3, fan 5, VRM, IDE CD/DVD cable, IDE
CD/DVD media backplane, microprocessor 2, system board
ServeRAID SAS controller (8k or 8k-l), DIMMs, tape power
(connector J100), system board
Low-profile PCI Express adapter (PCI slots 3 and 4), adapter on
PCI riser card (PCI slots 1 and 2), system board
193
Chapter 5. Diagnostics