SONY BRAVIA 40WE663 odd problem

[vikivng]

Re: SONY BRAVIA 40WE663 odd problem

Can you check if one of the pads that the shorted capacitor was connected to is connected to chassis (ground).
If it is then as a quick test I would solder a 10uF capacitor across the pads with the negative of the capacitor going to the grounded pad and check the voltage across it on powering up.

Hi, no connection between either pad and tv chassis.

[vikivng]

Re: SONY BRAVIA 40WE663 odd problem

Hi guys,
I didnt realise I had any responses.
nomoresonys,yes, the cap tests short out of circuit.
There was no change when I tested the set. I also tried a couple other caps from scrap boards.
Whilst looking at the board to find the same cap to test for matching, I realised there are 3 more of the same cap on the main board and 2 of them are testing short in circuit.
My question is (im sure it depends where on the circuit but..) would a mainboard with 2 shorted capacitors even boot the tv? Since sometimes the image does show for seconds.
Thnx for the replies guys im really trying to learn this craft.
Pls help me sort this set out.

[dick_barton]

Re: SONY BRAVIA 40WE663 odd problem

Can you check if one of the pads that the shorted capacitor was connected to is connected to chassis (ground).
If it is then as a quick test I would solder a 10uF capacitor across the pads with the negative of the capacitor going to the grounded pad and check the voltage across it on powering up.

[diif]

Re: SONY BRAVIA 40WE663 odd problem

It seems this was the only capacitor of this size on the board.
Is it a matter of testing other caps to see if it works since I have no reference point?

There is a capacitor at the bottom of your photo in post #15 that looks the same size.

[nomoresonys]

Re: SONY BRAVIA 40WE663 odd problem

The cap does read short out of circuit, correct?

[nomoresonys]

Re: SONY BRAVIA 40WE663 odd problem

Go ahead and turn on the tv for a minute see if the display is any different, just to see if there's any effect, maybe you can find one that size on a scrap board or even an old laptop may have one that size, they don't cost much, it's just the dam shipping on one little component that is no fun.

[vikivng]

Re: SONY BRAVIA 40WE663 odd problem

It looks like part of the step-down voltage system so would be needed. I don't think the set would work correctly with it missing.
Is there any other capacitor that looks identical in shape and size on the board you could compare it to in order to get an idea of its capacitor value.

It seems this was the only capacitor of this size on the board.
Is it a matter of testing other caps to see if it works since I have no reference point?

[dick_barton]

Re: SONY BRAVIA 40WE663 odd problem

It looks like part of the step-down voltage system so would be needed. I don't think the set would work correctly with it missing.
Is there any other capacitor that looks identical in shape and size on the board you could compare it to in order to get an idea of its capacitor value.

[vikivng]

Re: SONY BRAVIA 40WE663 odd problem

Great ..The cap has been removed and the short is gone..
Next question before I test. Is this an integral component.?
If so,,do i match by physical size.? Can I test without it ?
thnx guys.

[dick_barton]

Re: SONY BRAVIA 40WE663 odd problem

It may not be the capacitor but something connected to it. The only way to be sure it's not the capacitor is to unsolder it and check again.

[vikivng]

Re: SONY BRAVIA 40WE663 odd problem

Mr Barton said he wondered if maybe a cap is failing, I posted a video of testing them, tv isn't on our bench, we can't do it for you.

Yes I agree.

[vikivng]

Re: SONY BRAVIA 40WE663 odd problem

Thnx for replying.
this cap is testing short. I am assuming this should not be showing as such.?
Could this be the issue.?
Also getting 00v at both legs of that cap when power is on.
Looks like the culprit.?

[dick_barton]

Re: SONY BRAVIA 40WE663 odd problem

With the power to the set switched off check across the smd capacitors to see if any of them measure short circuit.

[nomoresonys]

Re: SONY BRAVIA 40WE663 odd problem

Mr Barton said he wondered if maybe a cap is failing, I posted a video of testing them, tv isn't on our bench, we can't do it for you.

[vikivng]

Re: SONY BRAVIA 40WE663 odd problem

Here are some pics of the board.
There is 12v on the output of the connector and at certain points on the board.
At the testing points going to the COF tabs I am getting .400v on one side and .300v on thw other.
#Is there meant to be 12v going to the tabs at all.?
There is also 1.8v at a couple of the caps going to the tabs.
can someone help me understand where the 12v needs to end.?

[nomoresonys]

Re: SONY BRAVIA 40WE663 odd problem

Can't tell just by looking, here's one example, he's using diode mode in this one, can also check for very low ohms: https://www.youtube.com/watch?v=jLd6QO7Z7m4

[vikivng]

Re: SONY BRAVIA 40WE663 odd problem

Close up inspection capacitors look new.
Obviously there would be no short to ground here as the tv would turn on at all ?
What am I checking for.?
I will try to get good photos today

[dick_barton]

Re: SONY BRAVIA 40WE663 odd problem

Thanks for the feedback.
Can you post good sharp pictures of you lcd panel board.
I wonder if one of the capacitors on it is failing. Seems to becoming a common problem.

[vikivng]

Re: SONY BRAVIA 40WE663 odd problem

Hi ,
sorry been out all day and have not had too much time to check any further.
When I power on with power supply set at 19v. The tv boots up drawing incremental amps until its peak draw at 1.98. It stays there for however long (random at this point) the image shows normally. Then , the instant the image disintegrates, the draw goes down the 1.84 amps.

[dick_barton]

Re: SONY BRAVIA 40WE663 odd problem

Are you saying you have a variable dc power supply set to 19V and the current drawn is as given above?
When it's showing a normal image for approx 10 seconds as you say, what is the current drawn by the supply?