Table of Contents
IC Block Diagrams
IC501 < Vertical Output > LA78040/TDA9302H
-
AMP
+
Pump
1
2
3
IC001 < Audio AMP.> AN5274
Service Information
I Protection Circuit
This TV set has a built-in power supply protection circuit.
It is provided to protect the TV set in case of a power supply circuit malfunctions. When something abnormality
occurs during TV reception, the TV set goes to the stand-by mode.
When an abnormality occurs during TV reception, it causes pin 27 of the CPU to go continually Low(less than
0.75V) for about one second. The CPU detects that this has occurred and outputs the signal from pin 31 to
switch off the power supply lines.
Releasing the protective circuit and restoring power supply
To release the protective circuit and restore power supply, turn the power to the TV set OFF and then ON again
via either the main power switch or the ON-OFF button on the remote control. This will work only if the power
supply trouble was temporary. If there is permanent trouble such as a damaged circuit, power cannot be
restored and the circuit will have to be repaired.
Thermal
Protection
Up
4
5
6
7
Volume
1
2
3
4
IC281 LA7642N
EQU-Adj
Vcc
Video In
16
15
ACC
Bell/EQU
Adj
ID-KIL
1
2
4.43DC
F0-Fil
Kil-Fil
+
-
Ripple
Filter
Protection
6
8
5
7
-7-
Kil-Out
AV/SECAM
4.43MHz In
14
13
11
12
System
SW3
SW2
Bell/EQU
PLL
SW1
Filter
DET
KILLER
LIM
Filter
F0 Adj
ID
4
3
5
6
ID-Fil
4M-DC
R-Y Out
+
-
Over
Current
Thermal
Circuit
9
10
11
12
SC-In
4MHz In
10
9
Pulse
DET
VCO
Pulse
I/F
Clamp
SW/ALC
8
7
B-Y Out
GND
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