Repair Of The Power Supply Circuit - Epson C117001-N - DFX 5000+ B/W Dot-matrix Printer Service Manual

5.3 REPAIR OF THE POWER SUPPLY CIRCUIT

This section provides detailed troubleshooting methods to isolate components in the power supply
or on the main board. This information is for use by servicers who repair to the component level.
U.S. servicers repair to the unit level only, and may ignore this section.
The table below provides causes, checkpoints, and solutions for different power supply circuit
problems. The checkpoints include waveforms for normal operation. By referring to the
checkpoints, determine the defective component. Then perform the proper repair. The table
provides the following four columns:
Check this column for a list of common printer problems.
Use this column to identify possible causes that could produce this symptom.
Follow the troubleshooting checks in this column to isolate your problem.
Repair the printer using the instructions in this column.
Table 5-4. C117 PSB/PSE Board Assembly Main Parts List
Location Name
NJM2903
Q101
Q201
Table 5-5. C117 PSB/PSE Board Assembly Component Repair
Symptom
No
DC voltage The
is present at the (HIGH level) is not
output. being sent from the
main board.
The DRERR signal
is HIGH.
HIGH.
Fuse F1 blows The line filter circuit
is defective.
immediately
after
replacement.
Rev. A
PWM switching controller
Comparator IC (voltage drop monitor for the two +35 VDC lines)
Main switching FET
Main switching FET
Cause
Look at the voltage waveform from
VPC signal
the gate array on the main board and
check the head driver voltage
waveform. (Refer to Table 5-6.)
Measure the voltage level of the
Measure the voltage level of the
Check if any of pins C1-C6 or RI is
shorting the AC line.
Description
Checkpoint
Troubleshooting
Solution
Replace the
gate array or
head driver
on the main
board.
Replace the
driver
head
on the main
board.
Wait until the
printer prints
again.
Replace the
abnormal
element.
5-13