EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: aqarwaen on January 12, 2020, 05:21:47 pm
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tv only shows black screen and only sound coming.
then i turn on from remote light turns white,it means its on..
visually inspected all capacitors but did not see any damage..did not measure any them..can anybody in theys pictures see anything wrong on theys boards?
https://imgur.com/a/JEjxhuO
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The power supply in these TVs is a model that is commonly known to fail.
The fact you have sound and no picture suggests you have no backlights
You are not going to diagnose the problem with just a visual inspection you will need to measure some voltages
First you need to check the voltage supplying the LED backlights. Looking at those pics there are two strings of LED lights as there are two connectors.
When you turn on the TV what voltage do you get supplying the LEDs? There are two 2 pin connectors one for each LED string (red/black and I think it is brown/white looking at those pics) . Measure each pin to ground and also measure the voltage across the two pins of each connector
What do you get? The voltage may not be steady, for example it may climb slowly to some voltage around 130V-150V then suddenly drop and start rising again.
The LED driver chip (MAP3022 or something like that) is on the other side of the PCB. It is also very common for the one or both of the LED strings to fail rather than for the PSU board to fail. What test equipment do you have? A multimeter is essential and a scope may be needed depending where the problem is. An LED back light tester would be very very useful but I doubt you will have that
Rich