Sanyo CP21G1 - IC501 < Vertical Output > LA78040;LA78040 N; IC001 < Audio AMP.> LA4266; Service Information and Procedures; Protection Circuit

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IC Block Diagrams
IC501 < Vertical Output > LA78040/LA78040N
Thermal
Protection
-
+
AMP
Pump
Up
1
INVERTING INPUT
2
Vcc
3
PUMP UP OUT
4
GND
5
Ver. OUTPUT
6
OUTPUT STAGE Vcc
7
NON INV. INPUT
IC001 < Audio AMP.> LA4266
12
34
5
6
7
8
9
10
NC NC
Filter PRE
GND
IN2
300Ω
30kΩ
NF2
OUT2
Power
GND
VCC NC
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