-7-
IC Block Diagrams
Service Information
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.
Protection Circuit
IC501 < Vertical Output > LA78040/TDA9302H
Thermal
Protection
-
+
AMP
Pump
Up
1
INVER
TING
INPUT
2
Vcc
3
PUMP
UP
OUT
4
GND
5
Ve
r.
OUTPUT
6
OUTPUT
ST
AGE Vcc
7
NON INV
.
INPUT
IC002 < Audio AMP.> LA4267
1
2
3
4
5
6
7
8
9
10
NC
NC
Filter
PRE
GND
IN2
300
Ω
30k
Ω
NF2
OUT2 Power
GND
VCC
NC
10
9
Pulse
DET
Pulse
I/F
Clamp
VCO
SW2
11
Filter
PLL
DET
12
13
System
SW1
LIM
KILLER
Bell/EQU
Filter
SW3
14
15
ACC
Bell/EQU
Adj
16
1
2
3
ID-KIL
ID
4
5
F0 Adj
6
7
SW/ALC
8
F0-Fil
Kil-Fil
4.43DC
ID-Fil
4M-DC
R-Y Out
B-Y Out
GND
4MHz In
SC-In
4.43MHz In
AV/SECAM
Kil-Out
Video In
Vcc
EQU-Adj
IC281 <SECAM Decoder> LA7642N
SM_14-C4FVR(RU) 1/6/05 2:23 PM Page 7
