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Operation
• Power Supply Protection
Condition 1: power supply interruption during power ON
If the power supply is interrupted, pin 34 of IC601 pulled HIGH, then TV
set will go to standby (protection mode) and LED starts blinking.
Condition 2: circuit malfunction when TV set is already ON
If TV set is under ON condition and circuit malfunction happened, pin 34
of IC601 pulled HIGH, then TV set will go to standby (protection mode)
and LED starts blinking.
• Excessive Current in +140V line :
When the break over voltage of D520 is exceeded, a HIGH level is applied to the
base of Q580.
Q520 ON → D520 ON → Q580 ON → Q581 ON → D583 ON → Pin 34 of
UOC HIGH → → Protection mode (LED blink)
• Overvoltage Of CRT Heater in X- Ray Protector Circuit :
When the heater voltage exceeds the zener (D511) breakover voltage, a HIGH
level is applied to base of Q580.
D511 ON (X-ray protector circuit) → Q580 ON → Q581 ON → D583 ON → Pin
34 of IC601 HIGH → Protection mode (LED blink)
• Excessive Voltage In Vertical Deflection Chip IC451 :
When an error in the vertical deflection circuit occurs, a LOW level is applied to
the base of Q400 causing the transistor to switch OFF. A HIGH level is fed via
D404 to base of protection Q581. Pin 34 of IC601 will pulled LOW to prevent the
picture tube neck broken.
Malfunction of vertical deflection stage → Q400 OFF → D404 ON → D583 ON
→ Pin 34 of IC601 HIGH → Protection mode (LED blink)
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