Hi.
Problem is inverter, backlight or PSU. The backlight lamps that illuminate the LCD display are flashing. This creates the "kind of strobe" effect that you see. There are several possible causes for the problem.
The lamps themselves are defective. The lamps do not fire up completely and keep flashing. The lamps are not sold alone but they are part of the LCD display. If the lamps are gone the TV is not worth repairing.
The inverter is the high voltage board that supplies the backlight lamps. If the inverter is defective it can still be replaced. Testing is done reading DC in, checking high voltage out, and using an oscillator to test the phase of the AC out signal generated by the inverter oscillator section.
PSU or main controllers may be defective. This will less common in case of flashing back-light. Test this if the inverter is OK and if the problem is DC voltage input to inverter.
Here parts:
42LA30H - ShopJimmyRegards.
Ginko
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