Epson DFX-8000 Service Manual page 229

Table 5-3. Power Supply Board Unit Component Repair (continued)
normal.
Checkpoint
Observe the waveforms at
switching the primary side (9 to 11) of
transistors are transformer Tl , and verify
bad. that 01 and Q2 are
switching (see Figure 5-12 ).
The rectifier diode Verify that the DC voltage
(approximately 35V)
between TPl(+) and TP2(-)
is output.
If no DC voltage is
l
output, check the
secondary (output) of Tl .
The current Check tf the outputs of any
limiting circuit is of IC2A (pin l), IC2B (pin 7)
and IC3B (pin 7) is at the
bad.
Vcc (12V) level.
The voltage Check if the output of IC4B
limiting circuit is (7 pin) is at the Vcc (12V)
bad. level. lf the output of IC4B
is normal, check that Q7 is
turned on.
GND level Check if the output of IC3A
monitor circuit is (pin 1) is at the Vcc (12V)
bad. level. lf the output of IC3A
is normal, check that Q7 is
turned on.
Transistor Q7 is The collector of transistor
bad.
None of the outputs of
l
CL signal (CN4 pin 3) is
output at the wrong time.
When the CL signal is
l
output, the PD signal is
output from the main
board to turn Q7 on.
FAN is bad. Remove connector CN5.
Solution
Replace Ql
and Q2, or the
surrounding
element(s),
including Tl
and T3.
Replace DTl or
the surrounding
element(s).
Replace the
abnormal IC(s)
or the
surrounding
element(s).
Replace IC4B o
the surrounding
element(s).
Replace IC3A o
the surrounding
element(s).
Replace Q7 or
the surrounding
element(s).
Replace IC5A o
the surrounding
element(s).
Replace the fan
5-15