IBM 6400 series Maintenance Manual page 100

undamaged and have good connections. Replace as necessary. (Refer
to Appendix A.)
5. Power on the printer. Run the print job again.
If the message appears, replace the CMX controller board. Record the
message and return it with defective CMX board.
124 PAPER FIFO OVERFLOW
SEE USER'S GUIDE
1. Paper First In First Out Overflow. Firmware error on the CMX controller board.
Cycle power. Run the print job again. If the message appears, download
the emulation software again.
2. Cycle power. Run the print job again.
If the message appears, replace the CMX controller board. Record the
message and return it with defective CMX board.
125 PAPER FIFO UNDERFLOW
SEE USER'S GUIDE
1. Paper First In First Out Underflow.
Cycle power. Run the print job again. If the message appears, download
the emulation software again.
2. Run the print job again.
If the message appears, power off the printer. Remove the paper guide
assembly or pedestal top cover. Make sure connectors P106 and P107
are fully seated on the CMX controller board.
3. Check hammer phasing.
Try using a lower phasing value; sometimes this message indicates too
high a hammer phase value.
4. Power on the printer. Run the print job again.
If the message appears, power off the printer. Make sure the MPU cable,
the hammer bank logic cable, and the hammer bank power cable are
undamaged and have good connections. Replace as necessary. (Refer
to Appendix A.)
5. Power on the printer. Run the print job again.
If the message appears, replace the shuttle frame assembly.
100 Troubleshooting