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DFX-8500
Rev. B
5-2
4
Table 5-7. Printer Mechanism Repair 2/4
Symptom Cause Checkpoint Solution
A particular dot
does not print.
The printhead is
defective.
Measure the printhead coil resistance.
(Refer to Figure 5-4 for details.)
Replace the
printhead.
Check whether a dot wire is worn. Replace the
printhead.
The print is too
light or print
density is not
uniform.
The printhead is
defective.
Check if the tip of a dot wire is worn. Replace the
printhead.
The parallelism value
is incorrect.
Print density differs at the right and left
sides of the page (darker on one side
than the other).
Perform the
parallelism
adjustment, as
described in Section
4.1.5.
The platen gap value
is incorrect.
Print density is too light even the new
ribbon cartridge is mounted.
Perform the
parallelism
adjustment, as
described in Section
4.1.5.
Printing is
performed, but the
printer does not
feed paper or
does not feed it
correctly.
Foreign objects are
lodged in the paper
path.
Visually check the paper path. Remove any foreign
substances.
The PF motor is not
driving the gear
properly.
Check whether the PF motor pinion
gear rotates smoothly when rotated
manually
Check backlash
between PF motor
pinion gear and
paper feed reduction
gear.
The PF motor is
defective.
Measure coil resistance for the PF
motor. (The correct resistance is
approximately 2.8 ohms + 10%.) Also
check the PF motor drivers.
Replace the PF
motor, and if drivers
are bad, replace
main board at the
same time
The ribbon feed
(RF) motor does
not operate.
The ribbon cartridge
is defective.
Remove the ribbon cartridge, rotate it,
and check whether it feeds the ribbon
normally.
Replace the ribbon
cartridge.
Foreign objects are
caught in the gears.
Check whether the ribbon driving gear
rotates when the cartridge is moved
manually.
Remove any foreign
objects or replace
damaged ribbon
feed mechanism
part (the ribbon feed
select gear, ribbon
feed transmission
gear, or ribbon feed
gear).
..