Epson TM-U950 Technical Manual page 126

CONFIDENTIAL
.
Table 4-1. Initialization Problems
Problem
Printer does not operate
at all.
Carriage-head vibrates,
emits an unusual sound,
and becomes error at
power-on.
Carriage-head vibrates,
emits an unusual sound,
and becomes error at
power-on.
Carriage-head first
moves normally, but
then hits the left border
of the frame-carriage
making an unusual
sound.
Rev. A
Probable Cause Level
Output voltage of B
external power supply
unit or internal regulator
circuit is not normal.
Reset circuit failure B
CPU oscillator circuit B
failure
Program ROM selection B
failure
RAM selection failure B
Gate array selection B
failure
Excessive tension of A
carriage transmission
belt
Detector-H.P. sub B
assembly failure
Wire break or bad B
solder point between
connector and carriage
motor terminals.
B
Motor-carriage B
defective
Too little backlash A
between carriage
motor gear and
carriage feed pulley.
Gear wear, damage, or A
contamination
A
TM-U950/U950P Technical Manual
Checkpoint Action
Check 24 V input Replace regulator IC
voltage at CN4 and (U9). Replace external
output voltage of power supply unit.
switching regulator.
Check voltage level at Replace IC (U4.)
RESET pin (pin 28) of CPU
(U12), U5 (reset: LOW).
Check oscillator output. Replace oscillator (X1).
Check input at pin 22 of Replace CPU (U12),
IC (U15). gate array (U19), and IC
(U11, 13, and 18).
Check input at pin 20 of Replace CPU (U12),
IC ((U16). gate array (U19), and IC
(U11, 13, and 18).
Check input at pin 59 of Replace CPU (U12) and
IC (U19). IC (U11, 13, and 18).
Check tension of Adjust the tension as
carriage transmission described in the
belt. Nominal value: 190 adjustment section of
±
( )10g(.42 (±).022 lbs) Chapter 5.
Use an oscilloscope to Replace the detector-
check the detector H.P. sub assembly.
output signal when the
carriage-head passes
the detector.
Check continuity Replace wiring board
between respective assembly.
terminals.
Check solder condition. Resolder as required.
None of the above Replace motor-carriage.
checks solves the
problem.
Check backlash. Adjust the backlash as
Nominal value: described in the
0.1(±)0.05mm (.0039 adjustment section of
(±).0020") Chapter 5.
Check gears for wear Replace any damaged
and damage. gear.
Check for dirt deposits or Remove any dirt
other foreign matter. deposits or foreign
matter.
Troubleshooting 4-13