Epson FX-870/1170 User Manual

Page 151

Principles of Operation

Table 6-8. Repairing the C094 MAIN Board Assembly (Continued)

Problem

Symptom

Cause

Checkpoint

Solution

Self-test

The printer

IC4 is

Check the head pulse signal at pin 31 (input)

Replace

printing

does not print defective.

and pin 63 (output).

abnormal

the self-test.

Self-test
printing
abnormal.

A particular
dot fails to

print.

One of the

Check the head drive signal at the base and

If the signal

head driie

the emitter of each transistor.

at the base

transistors

is normal,

is defective

replace the

transistor.

6, 8, 9, 10,

Otherwise,

11, or 12).

replace

6-36

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