Epson TM-FX2180 Service Manual page 38

EPSON FX-2180 Service Manual
Table 3-6. Repairing the Power Supply Board (Continued)
Problem Cause
The +35 V and Switching
+5 V lines are FET Q1 is
not output dead.
when the
printer is
turned on.
PC1 is
dead.
Q32 is
dead.
Q31 is
dead.
Checkpoint
Check that the resistance
between the source and the
drain is infinite.
Check the voltage waveform
between the source and the
drain of Q1.
Figure 3-8. Waveform 1
Check the waveform between
pins 3 and 4.
Figure 3-9. Waveform 2
Check that the resistance
between the collector and the
emitter is infinite.
Check that the resistance
between the source and the drain
is infinite.
Table 3-6. Repairing the Power Supply Board (Continued)
Solution Problem
Replace The +5 V line
Q1. is not output.
Replace
PC1.
Replace
Q32.
The PWDN
Replace
signal is
Q31.
constantly
HIGH.
Chapter 3 Troubleshooting
Cause Checkpoint
Chopper IC Check the waveform at pin 8
IC51 is of IC51.
dead.
Figure 3-10. Waveform 3
Check the waveform at
Q51 is
the collector of Q51.
dead.
Figure 3-11. Waveform 4
L51 is Check the resistance
dead. between the terminals of
L51.
IC51 is Check if the voltage of pin 6
dead. exceeds 1.3 V. If it does,
IC51 is dead.
Solution
Replace IC51.
Replace Q51.
Replace L51.
Replace IC51.
3-8