Epson TM-U950 - Page 128

Rev. A Troubleshooting 4-15
TM-U950/U950P Technical Manual
Dots are dropped
irregularly.
Print head FPC break B Check FPC for
continuity.
Replace print head unit.
Print head operation
failure
B Check wire tip for paper
or ink deposits.
Clean wire tip.
Print head wear B Above two checks have
been passed.
Replace print head unit.
Character width
changes irregularly.
Carriage transmission
belt tension is too low.
A Check carriage
transmission belt tension.
Nominal value: 190 ± 10
g (.42 ± .022 lbs)
Adjust the tension as
described in the
adjustment section in
Chapter 5.
Gears, carriage feed
pulley, or carriage
transmission belt wear or
damage
B Check parts for wear or
damage.
Replace parts as
necessary.
Print head wear B Above two checks have
been passed.
Replace print head unit.
Table 4-3. Printer Mechanism Problems
Problem Probable Level Checkpoint Action
Paper roll does not
advance, and printing is
all on the same line.
Paper roll supplying
problem
A Check whether paper
roll corresponds to
specifications.
Use paper roll that
corresponds to
specifications.
A Check paper roll path
for obstacles.
Remove any obstacles
and repair paper roll
path as required.
Roller-paper feed wear B Check surface of roller-
paper feed for wear and
damage.
Replace roller-paper
feed assembly.
Gear wheel wear B Check gear wheels for
wear and damage.
Replace gear wheels as
required.
Paper hold roller wear B Check surface and core
of paper hold roller for
wear.
Replace paper hold
roller.
J and R paper feed
motors drive signal
failure
B Check motor drive signal
at connector with an
oscilloscope.
Repair motor drive signal
generator circuit.
Wire break or bad
solder point in wiring
between connector and
motor-paper feed-J
and -R
B Check connection for
continuity.
Replace wiring board
assembly.
B Check solder condition. Resolder as required.
Paper roll does not
advance, and printing is
all on the same line
Motor-paper feed-J and
-R failure
B Above eight checks
have been passed.
Replace motor-paper
feed -J and -R.
Table 4-2. Printing Quality Problems (continued)
Problem Probable Cause Level Checkpoint Action
CONFIDENTIAL