Sony KDP-57XBR2 Training Manual page 55

+12V
R8176
FROM
Q8027
HV STOP 2
ABL
R8170
C8092
+12V
D8024
FROM
IC8007/7
REGULATION
CONTROL
R8134
+135V
R8133
HV Stop 2: Referring to Figure 11-6, the second HV protect circuit is shown. It functions in a similar manner as
HV stop 1 with a few differences. Q8031 monitors voltage from the flyback transformer rather than the HV block
assembly. Pin 5 of IC8010 will receive this signal and, instead of comparing it to a fixed reference, the ABL
voltage is used. The reason behind this design is to shut down the high voltage quickly if it is rising and flyback
current is simultaneously increasing. This severe condition can damage multiple components. The ABL voltage
at pin 6 will drop, while the HV sample at pin 5 increases. Q8028 will monitor flyback current in the same manner
as HV stop 1.
C8071
R8116
5.9V
D8036
R8111
C8062
C8065
R8106
D8030
R8115
P
Q8023
C8059
R8182
FIGURE 11-5 - HV STOP 1
11. RA-4/4A High Voltage Circuit Troubleshooting
+12V
3
1
2
D8025
IC8010
9.3V
2
1
3
IC8008
7.4V
+12V
R8107
IC8006
5.1V
2
4.6V
C8072
3
D8031
R8120
C8078 R8137
52
D8027
R8091
Q8019
R8087
C8053
+12V
R8102
1
C8060
11.5TVP14
TO
D8021
OR
HV STOP 2
TO HD
BUFFER
Q8005/B
N
6/3/02