Epson TM-U950 Technical Manual page 127

CONFIDENTIAL
Table 4-1. Initialization Problems (continued)
Problem
Motor-carriage does
not operate at all when
power is turned on and
becomes error.
Table 4-2. Printing Quality Problems
Problem
All dots do not print, or
print is very faint.
A certain dot does not
print.
4-14 Troubleshooting
Probable Cause Level
Carriage motor drive B
signal failure
Wire break or bad B
solder point between
connector and carriage
motor terminals.
B
Motor carriage B
defective
Detector-carriage sub B
assembly failure
Probable Cause Level
FPC is disconnected. A
Wire break or bad A
solder point in common
wire inside print head.
Wire break or bad B
solder somewhere on
the line between print
head unit and
connector.
Platen gap is not A
adjusted correctly.
Input pulse irregularity B
FPC wire break B
Wire break between B
soldered point of flat
cable on wiring board
and connector
terminals.
Print head coil wire B
break
Bad solder point B
between connector and
head coil.
Print head wire break B
Checkpoint Action
Check motor drive signal Repair motor drive signal
at connector with an generator circuit.
oscilloscope.
Check continuity Replace wiring board
between respective assembly.
terminals.
Check solder condition. Resolder as required.
Above three checks Replace motor-carriage.
have been passed.
Move the carriage-head Replace detector-
and check the carriage subassembly.
detection signal by using
an oscilloscope.
Checkpoint Action
Check FPC connector. Insert FPC again.
Check common wire for Replace print head unit.
continuity.
Check common wire for Resolder parts or replace
continuity. wire break parts.
Check platen gap. Adjust the gap as
Nominal value: described in the
0.50(±)0.05 mm adjustment section in
(.020(±).0020") Chapter 5.
Check dot wire input Repair input pulse
pulse with an control circuit or input
oscilloscope. pulse drive circuit.
Check FPC for Replace print head unit.
continuity.
Check wire between Replace wiring board
terminals for continuity. assembly.
Check coil resistance Replace print head unit.
with a multimeter.
Check wire between Resolder.
terminals for continuity.
Check for dot wire Replace print head unit.
break.
Rev. A