36
8. RA-4/4A Power Supply Troubleshooting
FIGURE 8-6 - REGULATION
FROM
Q6006/E
SOFT
START
11V
135V
V OUT
SENSE
IC6101
VCC CONTROLLER
SE135N
COLLECTOR
R6128
IC6005
VCC OUT
PC123FY2
R6028
D6023
D6024
R6033
R6029
C6027
E
AMP
1-
E AMP2-
REF OUT
DPC
E1
E2
IC6003
OSCILLATOR
IR3M02
TO
CONVERTER
DRIVER
IC6002 &
IC6004
1
3
2
1
2
4
3
1
6
RT
15
14
13
9
10
G BOARD
8.6TVP14
6/18/02
is the most common result obtained. IC1601 and its connection to the 135V line are the next check. The most
common cause of excessive B+ is an open or increase in value of the resistor connecting the 135V to IC1601
(R6115 in this chassis).
If shorting pin 2 of IC1601 does not stop the over-voltage problem, short pin 4 of IC6005. If the voltage now
drops, replace IC6005. If it still does not drop, IC6003 or one of the input components may be open.
Low B+: Check the voltage at IC6005, pin 1 and 2. There should be at least .6VDC difference with pin 2 being the
lowest. If there is, the optical isolator is being told to increase the frequency. If there is little or no voltage
potential across pins 1 and 2, disconnect pin 4 of IC6005. Turn the unit on and it should go into over-voltage
shutdown. If B+ is still low, check components at error input of IC6003 and if OK, replace the IC.