IBM 6400 Maintenance Information Manual page 123

Symptom
Randomly misplaced
dots
Vertical misalignment of
characters:
1. Dots or characters
move up or down from
dot row to dot row or line
to line
2. Incorrect spacing from
dot row to dot row or line
to line
3. Characters randomly
compressed and/or
enlarged
Table 5. General Symptom List
1. Power off the printer. Check and adjust the platen gap.
2. Remove the paper guide assembly or pedestal top cover. On the
left rear wall of the card cage, make sure the nut which secures
the line filter ground line and the AC-In Power Supply cable
leads to the ground stud is tight. (See Figure 53, page 280.)
3. Disconnect the AC power cord and check the ground leads for
continuity. Replace the AC power cord if it fails continuity test.
4. Make sure the printer is plugged in to a grounded power outlet.
Power up the printer. Run a print test. If the problem occurs,
replace the hammer bank logic cable.
5. Power up the printer. Run a print test. If the problem occurs,
replace the flash memory with pre-written flash and replace the
DRAM. (See Table 8 and Table 9 on page 219 and Figure 35 on
page 220.) Load the emulation software again.
6. Power up the printer. Run a print test. If the problem occurs,
replace the CMX controller board.
7. Power up the printer. Run a print test. If the problem occurs,
replace the power supply board.
8. Power up the printer. Run a print test. If the problem occurs,
replace the shuttle frame assembly.
1. Load paper. Press Form Feed and check that paper feeds
smoothly. Press View to verify that paper moves in both
directions. Check the forms thickness lever: if it is set too loose
or too tightly print quality can be affected. Set the forms
thickness lever to match the thickness of the paper being used.
2. Check the paper feed motor pulley for looseness. Hold the collar
snug against the motor pulley and torque the 7/64 inch setscrew
to 25 ± 2 inch-pounds (2.82 ± 0.23 N•m).
3. Check and adjust the paper feed timing belt. Replace the belt if it
is damaged.
4. Check and adjust the platen gap.
5. Inspect the tractors and tractor door springs for damage or
excessive wear. If either tractor is damaged or excessively worn,
replace both tractor assemblies.
6. Remove the paper guide assembly or pedestal top cover. Make
sure connector P107/PAPR M is fully seated in connector J107
on the CMX controller board.
7. Power on the printer. Load paper. Run a print test. If the problem
occurs, replace the paper feed motor.
8. Run a print test. If the problem occurs, replace the CMX
controller board.
9. Run a print test. If the problem occurs, replace the power supply
board.
General Symptom List
Corrective Action
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