Epson TM-U375 Technical Manual page 83

CONFIDENTIAL
Problem
Slip or validation paper
is not fed. (continued)
Cut sheet feed pitch is
irregular, or paper does
not advance and print-
ing is all on the same
line.
Paper roll near-end de-
tection does not work
properly. ( )
Different character than
input code is printed.
( ) This applies only when near-end detection is selected (ESC c 4 command) in the application program.
4-12
Table 4-3. Printer Mechanism Problems (continued)
Probable Cause Level
Poor adjustment of A
Solenoid-Paper
holding switching
position
C feed belt tension is A
loose.
Paper feed motor wire B
break
Main circuit board unit B
failure (Paper feed motor
drive signal failure)
Gear-Intermediate or In- B
termediate gear B wear
Cut sheet problem A
Paper roll is not installed. A
Pressure balance of S pa- B
per feed roller assem-
bly or V paper feed roller
assembly is not correct.
S paper feed roller as- B
sembly or V paper feed
roller assembly is defec-
tive or contaminated.
Cut sheet feed driving B
gears wear or damage
Main circuit board unit B
failure (Paper feed motor
drive signal failure)
Paper feed motor failure B
Microswitch failure A
Main circuit board failure B
(Receiver/driver IC failure)
Communication condition A
such as transmission
speed not set correctly.
Communication cable fail- A
ure
Checkpoint
Check attaching position of the
solenoid.
Check tension of the belt.
(Nominal value: 40 g (.088 lb))
Check resistance of Paper
feed motor.
(Nominal value: 40 Ω ± 5%)
Check paper feed motor drive
terminal signal of CN12 with
an oscilloscope.
Check the gears for wear and
damage.
Check whether slip or valida-
tion paper corresponds to
specifications.
Check paper roll installation.
Check the right and left bal-
ances of the roller assemblies.
Check surfaces of the roller
assemblies for wear and for-
eign matter.
Check gears for wear and dam-
age.
Check paper feed motor drive
terminal signal of CN12 with
an oscilloscope.
Above six checks have been
passed.
Check continuity between
microswitch terminals, and
check on/off operation.
Check IC (U3) output.
Check DIP switch settings.
Check to see if the cable is
RS-232C null modem cable,
and check its continuity.
Action
Adjust the solenoid attach-
ing position as described
in Main Assembly 7 in Sec-
tion 5.3.3.
Adjust the tension as de-
scribed in Adjustment B in
Section 5.3.4.
Replace Paper feed mo-
tor.
Repair paper feed motor
drive signal generator cir-
cuit.
Replace any damaged
gears.
Use paper that corre-
sponds to specifications.
(See Section 1.2.3, Paper
specifications .)
Install paper roll.
Replace S paper feed
roller assembly or V pa-
per feed roller assembly.
Replace or clean S paper
feed roller assembly and
V paper feed roller as-
sembly.
Replace any damaged
gears.
Repair paper feed motor
drive signal generator cir-
cuit.
Replace Paper feed motor.
Replace Microswitch
sub-assembly.
Replace IC (U3).
Set DIP switches correctly.
(See Section 1.3.5,
Switches and buttons .)
Replace cable.