IBM RS/6000 Enterprise Server M80 Service Manual page 161

a. Check the modem, modem cable, and serial port for loose or unconnected cables. Reset the
service processor using the pinhole reset switch on the primary I/O drawer operator panel.
b. If the hang repeats, check with service support to see if there is a firmware update that fixes the
problem.
c. If there is not, or the update does not fix the problem, replace the following FRUs one at a time in
this order:
1) Modem cable
2) Modem
3) I/O backplane in the primary I/O drawer
d. If this procedure does not fix the problem, call service support.
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Chapter 4. Checkpoints