IBM 6400 series Maintenance Manual page 120

7. If the printer has the coax/twinax expansion board, check the adapter connection
to the CMX controller board.
Make sure the 60-pin expansion adapter is correctly seated in the CMX
controller board and the coax/twinax expansion board.
8. Disconnect AC-in power supply cable connector P1. Set the circuit breaker to 1
(on). Measure AC voltage at pins 1 and 2 of connector P1.
If no voltage, replace the circuit breaker. If there is voltage, replace the
power supply board.
Operator panel blank
1. Power off the printer. Remove the paper guide assembly or pedestal top cover.
Check all cable connections into the CMX controller board; make sure the control
panel cable is seated in connector J110 on the controller board.
Connect all cables.
2. If the printer has the coax/twinax expansion board, check the adapter connection
to the CMX controller board.
Make sure the 60-pin expansion adapter is correctly seated in the CMX
controller board and the coax/twinax expansion board.
3. Power on the printer. Inspect the operator panel display and cooling fans.
If the operator panel is blank and the cooling fans come on, replace the
operator panel cable assembly and/or the operator panel, as required.
4. Power on the printer.
If the operator panel is blank and the fans not come on, replace the CMX
controller board.
Operator panel display shows garbled, broken characters
1. Remove the paper guide assembly or pedestal top cover. Check cable
connections into the CMX controller board. Make sure the control panel cable is
seated in connector J110 on the controller board.
Connect all cables.
2. Make sure the DRAM SIMM(s) is/are seated properly in J15/J16.
Reseat DRAM SIMM(s).
3. Power on the printer. Inspect the control panel display.
If the control panel shows broken characters, replace the DRAM.
120 Troubleshooting