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PCB failure analysis
1. CONTROL:
a. Abnormal noise on screen.
b. No picture.
2. MAIN (VIDEO):
a. Lacking color, Bad color scale.
b. No voice.
c. No picture but with signals output, OSD and back light.
d. Abnormal noise on screen.
3. POWER:
No picture, no power output.
Basic operation of LCD-TV
1. After turning on power switch, power board sends 5Vst-by Volt to Micro
Processor IC waiting for ON signals from Key Switch or Remote Receiver.
2. When the ON signal from Key Switch or Remote Receiver is detected, Micro
Processor will send ON Control signals to Power. Then Power sends (5Vsc,
18Vsc, 24V and RLY ON, Vs ON) to PCBs working. This time VIF will send
signals to display back light, OSD on the panel and start to search available
signal sources. If the audio signals input, them will be amplified by Audio AMP
and transmitted to Speakers.
3. If some abnormal signals are detected (for example: over volts, over current,
over temperature and under volts), the system will be shut down by Power off.
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