Epson DFX-8500 Service Manual page 198

DFX-8500
Symptom
A particular dot The printhead is
does not print. defective.
The print is too The printhead is
light or print defective.
density is not
uniform.
The parallelism value
is incorrect.
The platen gap value
is incorrect.
Printing is Foreign objects are
performed, but the lodged in the paper
printer does not path.
feed paper or
does not feed it
correctly.
The PF motor is not
driving the gear
properly.
The PF motor is
defective.
The ribbon feed The ribbon cartridge
(RF) motor does is defective.
not operate.
Foreign objects are
caught in the gears.
5-24
Table 5-7. Printer Mechanism Repair 2/4
Cause
Measure the printhead coil resistance.
(Refer to Figure 5-4 for details.)
Check whether a dot wire is worn.
Check if the tip of a dot wire is worn.
Print density differs at the right and left
sides of the page (darker on one side
than the other).
Print density is too light even the new
ribbon cartridge is mounted.
Visually check the paper path.
Check whether the PF motor pinion
gear rotates smoothly when rotated
manually
Measure coil resistance for the PF
motor. (The correct resistance is
approximately 2.8 ohms + 10%.) Also
check the PF motor drivers.
Remove the ribbon cartridge, rotate it,
and check whether it feeds the ribbon
normally.
Check whether the ribbon driving gear
rotates when the cartridge is moved
manually.
Checkpoint
..
Solution
Replace the
printhead.
Replace the
printhead.
Replace the
printhead.
Perform the
parallelism
adjustment, as
described in Section
4.1.5.
Perform the
parallelism
adjustment, as
described in Section
4.1.5.
Remove any foreign
substances.
Check backlash
between PF motor
pinion gear and
paper feed reduction
gear.
Replace the PF
motor, and if drivers
are bad, replace
main board at the
same time
Replace the ribbon
cartridge.
Remove any foreign
objects or replace
damaged ribbon
feed mechanism
part (the ribbon feed
select gear, ribbon
feed transmission
gear, or ribbon feed
gear).
Rev. B