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10. RA-4/4A Deflection Circuit Troubleshooting
1
8
1
7
6
5
4
3
2
6
5
4
2
1
12
11
10
9
8
6
D BOARD
Q5020/E
PIN OUT
1
4
1
4
1
4
FIGURE 10-2 - H OUT
DF VCC
D5015
C5045
R5062
R5055
CN5002
+135V
C5012
R5032
R5026
C5016
T5002
HOT
+12V
FROM
IC5002 R5003
C5005
Q5008
H DRIVE
N
C5010
R5011
Q5002
P
CN5004
H
DRIVE R5002
T5001
HDT
R5031
C5019
PS5001
PS5002
D5007
D5003
D5009
R5046
R5049
Q5013
H OUT
N
C5038
C5041
R5074
C5039
D5013
R5007
C5091
C5032
C5092
C5052
R5008
C5088
L5007
C5051
R5030
C5043
C5042
TO 5019/B
H PULSE
SHAPER
CN4304
B-H
DEF
RET
CN4107
RET
R-H
DEF
REH
G - H
DEF
CN4206
10.2TVP14
7/11/02
-135V
Figure 10-2 illustrates the output section of the horizontal deflection stage. Since no flyback transformer is
utilized, pulses will be generated by the collapse of the field in the horizontal deflection yokes and T5002. This
transformer will provide a boosted voltage for the dynamic focus correction circuit via R5055 and D5015. It also
generates a positive and negative voltage source that will be applied to the red and blue CRTs. This will provide
the necessary offset for centering since these tubes are not in the center of the optical path. Notice that the
collector of Q5013 does not have a B+ source. A negative 135V source is applied at the emitter and this voltage
will vary based on conduction of the pincushion output transistor, Q5020. Pincushion correction will be discussed
later.
Troubleshooting
The lack of a flyback transformer simplifies the troubleshooting of this circuit since it is usually the cause of
horizontal output failures. The procedure to follow when replacing a shorted horizontal output transistor remains
the same.
Occasionally, you will be fortunate to have the output transistor fail and nothing else is the cause. Usually,
however, you end up losing the newly installed transistor if certain precautions are not followed. In the worst
case, this might cause the power supply switching transistors to fail. Always treat a shorted horizontal output as
though something else caused it to fail. The use of a variac and an oscilloscope will help insure this.