Epson LQ-300 - Impact Printer, Service Manual

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Troubleshooting Service Manual
Table 5-8. Repairing the Printer Mechanism (Continued)
Problem
Symptom Cause Checkpoint
Self-test A particular
The Measure the pnnthead the
printing is
dot is missing. is defective. resistance. it should be (and
abnormal.
approximately 54.7 if the
drivers, if
is shorted, also
necessary).
check the drivers.
Check to see if the dot wires
Replace the
are worn.
The printing is The Check whether the tips of the Replace the
too light, or the is wires are worn.
print
density is
The
Set the gap adjustment lever to Adjust the
not uniform.
gap is not the first position, and check the gap. Refer to
properly platen gap. The appropriate Section 4.1.1,
adjusted.
value is 0.45 mm. Platen Gap
Paper feed is
Printing is per- Foreign Perform a visual check of the Remove any
abnormal. formed but the substances paper path. foreign
paper is not are in substances.
fed or is not the paper path.
fed uniformly.
The PF motor Check that no foreign Remove any
is not driving substance is between foreign
the gear the gears and that the gears substances.
correctly. are not broken or worn. the
PF motor
reduction
gears.
Replace the
paper pickup
gears.
The PF motor Measure the coil resistance for Replace the
is defective. the PF motor. The approximate PF motor (and
value should be 56 if the
drivers, if
motor is also check
necessary).
the drivers.
ribbon
The ribbon is The ribbon Remove the ribbon cartridge, Replace the
‘eed is not turning. cartridge is rotate its ribbon feed knob ribbon
defective. manually, and see if the ribbon cartridge.
feeds normally.
Foreign Cheek whether the RD ratchet Remove any
substances rotates when the carriage is foreign
are caught in
moved substances.
the gears. .
Replace the
ribbon feed
mechanism.
The ribbon The planetary Move the carriage manually; Replace the
feeds properly gear is check whether the planetary ribbon feed
only when the defective.
gear turns in reverse and
mechanism.
carriage
engages the gear.
moves in one
direction (i.e.,
it fails to
feed
when the
carriage
moves in the
other
direction).
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