Epson FX-880 Service Manual page 47

Table 3-12. Repairing the Printer Mechanism (continued)
Symptom
Problem: Self test printing is not executed.
A particular dot is
missing.
The printing is too
light, or the print
density is not
uniform.
Problem: Paper feed is abnormal.
Printing is performed
but the paper is not
fed or is fed
uniformly.
Problem: The ribbon is abnormal.
The ribbon is not
turning.
The ribbon feed
properly only when
the carriage moves
in one direction (i.e.,
it fails to feed when
the carriage moves
in the other
direction).
Rev. A
Cause
The printhead is
defective.
The printhead is
defective.
The platen gap is
properly adjusted.
Foreign substances
are lodged in the
paper path.
The PF motor dose
not drive the
mechanism.
The PF motor is
defective.
The ribbon cartridge is
defective.
Foreign substances
are caught in the
gears.
The planetary gear in
the ribbon drive gears
is defective.
Checkpoint
Measure the printhead coil
resistance. It should be
about 8 ohms. If the
printhead is shorted, also
verify the drivers on the
main board.
Verify whether head wire is
born or not.
Verify whether head wire is
born or not.
Set the gap adjustment
lever to the first position,
and check the platen gap.
The correct PG is 0.365
0.015.
Verify the paper path
whether any foreign
substance is put on.
Verify the mechanism
whether any foreign
substance is put on.
Measure the motor coil
resistance. It should be
about 16 ohms. If the motor
is shorted, also verify the
drivers on the main board.
Remove the ribbon
cartridge, verify to rotate its
knob manually, and to see if
the ribbon feeds normally.
Verify whether the RD
ratchet rotates when the
carriage is moved manually
toward left and right.
Move the carriage manually:
verify whether the ribbon
feed gears turns in reverse
and engages the gear.
FX-880 Service Manual
Chapter 3 Troubleshooting
Solution
Replace the
printhead, (and
drivers , if
necessary).
Replace the
printhead.
Replace the
printhead.
Adjust the platen
gap. Refer to
Chapter 5.
Remove any
foreign
substance.
Remove any
foreign
substance.
Replace the PF
motor, (and
drivers , if
necessary).
Replace the
ribbon cartridge.
Remove any
foreign
substances.
Otherwise,
replace the ribbon
feed mechanism.
Replace the
ribbon feed
mechanism.
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