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TV-Tech1, Technician
Category: Electronics
Satisfied Customers: 5316
Experience:  30 years servicing Tellys
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, i have a 40" samsung tv and my picture disapears after

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hi, i have a 40" samsung tv and my picture disapears after a couple of hours watching, but still have sound though. If I switch it off for a while and then start all over again
Hello, I'm TV Tech1 and I'll be working with you to identify and help you resolve your problem.
You need to remove the back cover to expose the back of the TV. Turn it on. Let it run until the picture disappears. On the back there are usually holes where you can see if the backlighting is still lit. If not, turn off any lighting so you can see if the screen is still glowing in the dark. That's the first thing you need to know. Let me know if the panel is still lit during the loss of picture.
Customer: replied 3 years ago.

No backlighting at all, just sound

Ok, How about a picture of the rear of the chassis so I can give instructions to you, AND the model number of the TV set too.

Example --

Customer: replied 3 years ago.

Samsung PS43D490A1WXXU SER. B2T534PB500047N

With the back cover removed, you'll need a volt/ohmmeter aka DMM to run a short test on the plug marked with VS and GND.

Using those same test points, but with the plugs disconnected from the power supply board, you want to see if the green light blinks once a second, and your power supply board has about 200 Volts DC on the power board's VS and GND pins. Here is a picture of the tests you need to do ---

Let me know the results of those tests, because the X main may be shorted, or the Ymain is shorted. Removing the shorted board should let the power board activate and supply 200 volts DC on the Vs and GND pins on the power board. And if that's good, you should see that green light blink once a second if it's working ok.

Customer: replied 3 years ago.

Thank you so much for all your help, I managed to narrow it down to the Ymain board being shorted. It was a bit difficult being intermittent, but with a little bit of patience it all worked out.

Regards, ***** ***** Beer

Ps. I have ordered the Ymain board. Luckily not too expensive.

Glad you got it isolated. Odd that it's intermittent, but you must have caught it in time before it completely died on you.
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