38
9. RA-4/4A Protect Circuit Troubleshooting
IC007
MAIN
NVM
IC6102
OVP OCP
uP393C
RM +5V
+135V
T601/7
11V
+22V
+19V
+15V
+7V
R6118
MA BOARD
Q101
LVP
+5V
D3102
CN3101
CN514
OTMRED
IC1008
MAIN CPU
CXP85848-016Q
SDA
SCL
ONVMWE
10SDAT
10SCLK
8
5
2
1
7
6
6
6
48
50
55
49
47
IC511
VIDEO
PROC.
CXA2101
AQ
56
55
7
5
6
6
6
6
6
5
5
6
6
7
13
50
48
6
5
4
3
WP
B+OVP
B+OCP
IC1009
OSD CPU
CXP85340A-
2560
HV PROT.
H PROT.
V PROT.
A PROT.
SCL
SDA
A BOARD
R1116
R1113
R1107
R1104
D1005
D1007
D1006
FROM HV PROTECT
D8021/K D BD.
FROM H PROTECT
Q5006/C D BD.
FROM V PROTECT
Q5005/C D BD.
FROM A PROTECT
Q2610/C K BD.
CN505
CN6101
TO
D6002
D6123
D6124
LATCH
Q6102
Q6103
VCC SW.
CIRCUIT
1
2
4
3
RY6001
AC
LINE
G BOARD
FIGURE 9-1 - PROTECTION BLOCK
9.1TVP14
5/23/02
Audio:
DC voltage has been detected on one or both of the audio out lines. The set is shut down to protect the
speakers. This is usually caused by shorted audio amp IC406.
WDT:
A communications error has occurred. The main CPU is unable to communicate with the Y/C jungle IC.
The timer LED blinks continuously at one-second intervals and as soon as 101 of them occur, a failure is registered.
Protection Circuits Not Covered By Self-Diagnostics
The block diagram shown in Figure 9-1 illustrates an overall view of the circuits that are monitored. Notice that
all of the protect items that appear on the diagnostic screen are connected to IC109 along with routing to the
relay latch transistors. If a problem develops on any of these lines, IC1009 will communicate this information to
the main CPU, IC1008 and the failure written to NVM along with the appropriate flash sequence of the timer LED.