IBM 6400 series Maintenance Manual page 107

Check the security PAL at location U54 on the CMX controller board. If
the PAL is absent, install the correct PAL. If a security PAL is present,
replace it.
2. Power on the printer.
If the message appears, replace the replace the CMX controller board.
Record the message and return it with the defective board.
ERROR: SHORT AT ADDRESS XXXX
1. Hardware failure in DRAM or CMX controller circuitry.
Download the program again. If the message appears again, replace the
DRAM. If message occurs with new memory, replace the CMX controller
board. Record the message and return it with defective CMX board.
FM HEADER ERROR
1. Frame Header Error. Application software has violated header parameters.
Not a printer problem. The system administrator should correct
applications data or configuration.
HAMMER BANK NOT INSTALLED
1. Self-test routines do not detect hammer coils at printer start-up. Power off the
printer. Verify that the shuttle frame assembly is installed.
Install the shuttle frame assembly.
2. Remove the paper guide assembly or pedestal top cover. Verify that the hammer
bank logic cable is connected to connector J108 on the CMX controller board and
to the shuttle frame assembly.
Connect the hammer bank logic cable to connector J108 on the CMX
controller board and to the shuttle frame assembly.
3. Power on the printer.
If the message appears, replace the hammer bank logic cable.
4. Power on the printer.
If the message appears, replace the shuttle frame assembly.
5. Power on the printer.
If the message appears, replace the CMX controller board. Record the
message and return it with the defective board.
Troubleshooting 107