IBM 6400 Maintenance Information Manual page 121

Symptom
Characters or dots are
missing, smeared, too
light, or too dark
Table 5. General Symptom List
Print Quality
1. 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 tension between the tractors. Adjust the right
tractor so that it does not pull paper too tightly or leave it too
loose. The right tractor should hold the paper under "slight"
tension.
3. Inspect the shuttle frame assembly for print chaff, debris, or ink
residue that could be causing the problem. Clean the shuttle
frame assembly.
4. Check the ribbon for folds or tears. Check that the ribbon guides
are tight and the ribbon tracks straight across them. Rewind or
install new ribbon. If the ribbon does not track straight across the
ribbon guides, adjust the ribbon guides. If the ribbon guides are
loose, tighten them. If the ribbon guides are damaged, replace
them.
5. Power off the printer. Remove the shuttle cover. Remove the
shuttle frame assembly. Inspect the ribbon mask for bends or
deformation that adversely affect paper feeding. Make sure the
hammer bank cover assembly is correctly installed on its
mounting pegs. Check the shuttle frame assembly for broken
hammer springs, hammer tips, or contaminations. Replace any
damaged hammer spring assemblies. Replace the hammer
bank cover assembly if it is deformed or damaged.
6. Inspect the paper ironer. If the paper ironer has slipped up into
the print line, reposition the paper ironer.
7. Check and adjust the platen gap.
8. Remove the paper guide assembly or pedestal top cover. Make
sure connectors P105 and P108 have good connections on the
CMX controller board. Make sure connectors P04 and P05 have
good connections at the shuttle frame assembly.
9. Print out the configuration. (Refer to the User's Manual .) Call
support to confirm the correct microcode levels, especially the
DC and EC levels. If the code levels are incorrect, download the
correct microcode (page 175) and reload the flash memory
(page 176).
10. On 475 lpm and 500 lpm printers, check the shuttle speed (page
182). Adjust the shuttle speed as necessary to match the
printer's rated speed.
11. Power on the printer. If the problem still occurs, replace the
hammer bank logic cable and the hammer bank power cable.
12. Power on the printer. If the problem still occurs, replace the
shuttle frame assembly.
General Symptom List
Corrective Action
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