Epson U375 - TM B/W Dot-matrix Printer, Техническое руководство

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4-9
Table 4-1. Initialization Problems (continued)
Table 4-2. Printing Quality Problems
Level
A
B
B
A
B
B
B
B
B
B
Level
A
A
B
B
B
B
B
Action
Replace any damaged
gears.
Remove any dirt deposits
or foreign matter.
Repair carriage motor
drive signal generator cir-
cuit.
Replace Relay board
sub-assembly.
Resolder as required.
Replace Carriage sensor
sub-assembly.
Replace Carriage motor.
Action
Insert the FFC-Print head
again.
Resolder parts or replace
Print head unit.
Resolder parts or replace
broken wires.
Adjust the gap as de-
scribed in
Adjustment D in
Section 5.3.4.
Repair input pulse control
circuit or input pulse drive
circuit.
Replace FFC-Print head.
Replace Relay board
sub- assembly.
Replace Print head unit.
Resolder.
Replace Print head unit.
Problem
Carriage first moves
normally, but then hits
the left side of the print
frame, making an un-
usual sound.
Carriage motor does
not operate at all when
power is turned on, and
causes an error state.
Probable Cause
Wear, damage, or con-
tamination of carriage
drive gears
Main circuit board fail-
ure (Carriage motor drive
signal failure)
Wire break or bad solder
point between connector
and carriage motor termi-
nals.
Carriage sensor sub-
assembly failure
Carriage motor failure
Checkpoint
Check gears for wear and dam-
age.
Check for dirt deposits or other
foreign matter.
Check input signal to carriage
motor drive terminal of CN13
with an oscilloscope.
Check continuity between re-
spective terminals.
Check solder condition.
Move the Carriage motor and
check the timing detection sig-
nal with an oscilloscope.
Above four checks have been
passed.
Problem
All dots do not print.
A certain dot does not
print.
Probable Cause
FFC-Print head is discon-
nected.
Wire break or bad solder
point in common wire in-
side print head.
Wire break or bad solder
point somewhere in the line
between Print head unit
and connector.
Platen gap is not adjusted
correctly.
Input pulse irregularity
FFC-Print head wire break
Wire break between con-
nector terminals of Relay
board sub-assembly.
Print head coil wire break
Bad solder point between
connector and head coil.
Print head wire break.
Checkpoint
Check the FFC connection.
Check common wire for conti-
nuity.
Check common wire for conti-
nuity.
Check platen gap.
Nominal value: 0.65
±
0.05 mm
(.026
±
.0020")
Check dot wire input pulse with
an oscilloscope.
Check the FFC for continuity.
Check the terminals for continu-
ity.
Check coil resistance with a
multimeter. (Nominal value:
15.6
Ω ±
7% at 25
°
C (77
°
F))
Check wire between terminals
for continuity.
Check for dot wire break.
CONFIDENTIAL