IBM 6400 series Maintenance Manual page 124

If the ONLINE indicator does not light, replace the stacker control panel.
6. Power on the printer. Check that the ONLINE indicators lights on the stacker
control panel.
If the ONLINE indicator does not light, replace the CMX controller board.
Printer does not print self tests
1. Power off the printer. Remove the paper guide assembly or pedestal top cover.
Disconnect the control panel cable from connector J110 on the CMX controller
board. Disconnect the control panel cable from the control panel. Check
continuity of the control panel cable assembly.
Replace the control panel cable assembly if it fails continuity test.
2. Connect the control panel cable assembly to J110 on the CMX controller board
and to the control panel. Power on the printer. Load paper. Run a self test.
If the self test does not run, replace the control panel assembly.
3. Power on the printer. Run a self test.
If the self test does not run, replace the CMX controller board.
Reverse paper feed: platen does not open
1. Raise the forms thickness lever and check that the platen opens.
If the platen opens with difficulty, inspect for and remove jams or
obstructions.
2. Check the platen open pulley and the platen pulley for looseness.
Bottom out the platen open motor pulley on the motor shaft and torque
the 1/16 inch set screw to 9
the 7/64 inch setscrew in the platen shaft pulley, then open and close the
forms thickness lever and check that the platen pulley setscrew does not
hit the left ribbon guide.
3. Check the condition and tension of the platen open belt.
Adjust the platen open belt. Replace the belt if it is damaged.
4. Check the platen gap.
Adjust the platen gap.
5. Power off the printer. Remove the paper guide assembly. Disconnect connector
P106 from the CMX controller board. Check the resistance of connector
P106/PLAT M. (Refer to the Main Wire Harness Test Tables on page 297.)
124
2 inch-pounds (1.02 0.23 N m). Tighten
Troubleshooting