Principles of Operation

Component Repair Information (for Dealers Outside the U.S.)

This portion of the manual provides additional information for servicers outside the U.S. who need to make repairs to components on the circuit boards. (U.S. service technicians can ignore these pages.)

Repairing the C076 PSB Board Assembly

This section gives instructions for repairing the C076 PSB board assembly. It describes various problems, likely causes, checkpoints, and solutions. The checkpoint column provides proper waveforms, resistance values, and other information for each component of the C076 PSB.

WARNING

The OPERATE button on the control panel only turns the secondary power circuit on or off, so the primary power circuit is live as long as the printer is connected to an AC power outlet. Do not touch the heat sink attached to the FET (Ql) when the printer is powered.

Table 6-7. Repairing the C076 PSB Board Assembly

Problem

 

Cause

 

Checkpoint

 

Solution

 

 

 

 

 

 

The +35 V line isDiode bridge DBl

 

Measure the DC voltage between pins 3 and 4 of

 

qeplace
Sad.1 i sb a d .

 

DBl .

 

IBl.

 

 

 

 

 

 

 

 

Thetransformer

 

Measure the resistance of the Tl transformer coils

 

qeplace Tl .

 

 

 

 

coils are open.

 

at pins 3-2, 5-4, 1 O-l 1, and 11-9.

 

 

 

 

 

 

 

 

 

Ql is bad.

 

* Check the voltage waveforms at Ql.

 

qeplace Ql .

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CH1=50V

 

 

TIME=2ps

 

 

 

 

I

 

I

 

 

I

I

 

Epson FX-870/1170