Epson TM-U950 Technical Manual page 128

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