4-8
Checkpoint
Check 24 V input voltage at
CN6 and output voltage of
DC +5 V / +24 V control cir-
cuit.
Check voltage level at RE-
SET terminal (pin 28) of CPU,
U12 (reset: LOW).
Check oscillator output.
Check input at pin 22 of IC
(U15).
Check input at pin 20 of IC
(U16).
Check input at pin 59 of IC
(U19).
Check belt tension.
Use an oscilloscope to check
the sensor output signal when
carriage passes the sensor.
Check continuity between re-
spective terminals.
Check solder condition.
Above four checks have been
passed.
Problem
Printer does not oper-
ate at all.
Carriage vibrates,
emits an unusual
sound, and causes an
error state at power-on.
Probable Cause
Output voltage of external
power supply or Main cir-
cuit board failure (Abnor-
mal regulator circuit)
Main circuit board failure
(Abnormal reset circuit)
Main circuit board failure
(Abnormal CPU oscillator
circuit)
Main circuit board failure
(Program ROM selection
failure)
Main circuit board failure
(RAM selection failure)
Main circuit board failure
(Gate array selection failure)
Excessive belt tension
Home position sensor
sub-assembly failure
Wire break or bad solder
point between connector
and carriage motor termi-
nals.
Defective Carriage motor
4.1.3 Troubleshooting Tables
If a problem that can be verified by visual examination has
occurred, use the tables below to determine the cause and
perform repairs.
There are three tables, divided by symptom category:
Table 4.1 Initialization Problems
Table 4.2 Printing Quality Problems
Table 4.3 Printer Mechanism Problems
The tables contain the following columns:
● Problem
This is the symptom that can be verified.
● Probable Cause
This is a listing of one or several possible causes that
should be examined.
● Level
Level A
The problem can be corrected by persons who are
familiar with the printer and have general knowledge, but
special technical skills are not required.
Level B
The problem requires thorough knowledge and familiar-
ity with the printer as well as technical skills and experi-
ence.
● Checkpoint
These are one or more areas in the printer that should be
checked.
● Action
These are the steps to correct the problem. If the prob-
lem persists after taking these steps, check the other
possible causes listed.
Level
B
B
B
B
B
B
A
B
B
B
B
Action
Replace external power
supply unit or regulator IC
(U9) / FET (Q33).
Replace IC (U4).
Replace oscillator (X1).
Replace CPU (U12), gate
array (U19), and IC (U11,
13, and 18).
Replace CPU (U12), gate
array (U19), and IC (U11,
13, and 18).
Replace CPU (U12) and
IC (U11, 13, and 18).
Adjust the tension as de-
scribed at step 18 in
Sub-
assembly I
in Section
5.3.2.
Replace Home position
sensor sub-assembly.
Replace Relay board
sub-assembly
Resolder as required.
Replace Carriage motor.
Table 4.1 Initialization Problems
CONFIDENTIAL
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