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 4, “Parts listing, Types 4255, 7945, and 7949 server,” on page 157 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.
v Go to the IBM support Web site at http://www.ibm.com/systems/support/ to check for technical
information, hints, tips, and new device drivers or to submit a request for information.
Symptom Action
The server unexpectedly shuts
down, and the LEDs on the
operator information panel are
not lit.
See “Solving undetermined problems” on page 154.
Serial device 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 4, “Parts listing, Types 4255, 7945, and 7949 server,” on page 157 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.
v Go to the IBM support Web site at http://www.ibm.com/systems/support/ to check for technical
information, hints, tips, and new device drivers or to submit a request for information.
Symptom Action
The number of serial ports that
are identified by the operating
system is less than the number
of installed serial ports.
1. Make sure that:
v Each port is assigned a unique address in the Setup utility and none of the
serial ports is disabled.
v The serial-port adapter (if one is present) is seated correctly.
2. Reseat the serial port adapter, if one is present.
3. Replace the serial port adapter, if one is present.
A serial device does not work.
1. Make sure that:
v The device is compatible with the server.
v The serial port is enabled and is assigned a unique address.
v The device is connected to the correct connector (see “Rear view” on page
12).
2. Reseat the following components:
a. Failing serial device
b. Serial cable
3. Replace the following components one at a time, in the order shown, restarting
the server each time:
a. Failing serial device
b. Serial cable
c. (Trained service technician only) System board
Chapter 3. Diagnostics 59