IBM 7940, Problem Determination And Service Manual

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Power problems
v Follow the suggested actions in the order in which they are listed in the Action column until the problem
is solved.
v
See Chapter 3, “Parts listing, Type 7940 and 7941 servers,” on page 19 to determine which components
are customer replaceable units (CRU) and which components are field replaceable units (FRU).
v If an action step is preceded by “(Trained service technician only),” that step must be performed only by a
trained service technician.
Symptom Action
The power-control button does
not work.
Note: The power-control button
will not function until 20
seconds after the server has
been connected to ac power.
1. Make sure that the power-control button is working correctly:
a. Disconnect the server power cord.
b. Reconnect the power cord.
c. Press the power-control button.
d. If the server does not start:
v
Disconnect the server power cord and reseat the operator information
panel cables; then, repeat steps 1a through 1c.
v If the problem remains, replace the operator information panel.
2. Make sure that:
v
The power cord is correctly connected to the server and to a working
electrical outlet.
v
(Trained service technician only) The microprocessor is correctly installed.
3. If you just installed an optional device, remove it, and restart the server. If the
server now turns on, you might have installed more devices than the power
supply supports.
4. Replace the following components one at a time, in the order shown, restarting
the server each time:
a. Power supply.
b. (Trained service technician only) system board.
5. See “Solving undetermined problems” on page 121.
The server does not turn off.
1. Determine whether you are using an Advanced Configuration and Power
Interface (ACPI) or a non-ACPI operating system. If you are using a non-ACPI
operating system, complete the following steps:
a. Press Ctrl+Alt+Delete.
b. Turn off the server by pressing the power-control button for 5 seconds.
c. Restart the server.
d. If the server fails POST and the power-control button does not work,
disconnect the ac power cord for 20 seconds; then, reconnect the ac power
cord and restart the server.
The server unexpectedly shuts
down, and the LEDs on the
operator information panel are
not lit. See “Solving undetermined problems” on page 121.
Chapter 5. Diagnostics
95