42" Spectrincq no power

[avaktech]

Rescued an off brand 42" LCD tv from a local landfill today. Going through power supply and found an open fuse and a couple bulging caps. Tv does not power on at all, no light, nothing. Only thing possibly fishy is a closed 400v polyester foil capacitor. I am very inexperienced so can someone with knowledge tell me if these types of capacitors would normally appear shorted? If it is a problem what else should I check? Thanks
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[budm]

Re: 42" Spectrincq no power

Please post good clear pictures of all the boards so we can see how they are connected, pictures of the cap? Please use attachment function to post the pictures.
We are trying to troubleshoot the problem without having the boards in front of us, so good clear pictures are very important.

[selldoor]

Re: 42" Spectrincq no power

]per other thread

Also found these two resistors both look fully closed, does anyone wanna chime in on the value for these?
Attached Images
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Old Today, 04:05 AM #3
selldoor

There is no need to start multiple threads with the same question - let this one die and use the main one.
Resistor values - why not look them up yourself?
Type hobby hour resistor into your search engine.

avaktech
New Member

Join Date: Jan 2012[
Posts: 18

I noticed the tv repair threads and decided to move over there. Not trying to be pushy, sorry. And yes I did look up the colors on multiple charts and calculators but none of the showed silver or gold in the positions of the ones I pictured. I am guessing they are just fusibles but dont really know.
Dont look like fusibles.
OK see attached - please can you update profile with country and mains voltage

[avaktech]

Re: 42" Spectrincq no power

I noticed a repair kit online for the board:ad301m24-4n1 I ran a few tests at these locations but am not very experienced so not sure what I'm doing exactly.. The SMD resistors all seems within spec. There is some sort of controller in the kit and the small heatsink attached to it has come loose so it is suspect, however I have no idea how to test it?

[tom66]

Re: 42" Spectrincq no power

PICTURES!! Or we can't help you locate things!

[selldoor]

Re: 42" Spectrincq no power

Budm is the man for that - as he says we will need clear pictures - might help if you post a link to the kit.

[avaktech]

Re: 42" Spectrincq no power

Alright guys here's some pics, not the greatest

[avaktech]

Re: 42" Spectrincq no power

Here's another with the other sink cover removed, I'm having a hard time getting the lighting right.

[budm]

Re: 42" Spectrincq no power

I can see some caps with domed tops. This power supply looks familiar, I think TOM have seen this before in VESTEL?

[avaktech]

Re: 42" Spectrincq no power

There is definately bad caps, several, however the main fuse is open so i am trying to be cautious. I don't wanna do more damage by just doing the caps. I haven't been able to find a glaring fault yet. Thats why I was asking about the 400 volt poly foil cap, it seems shorted is this normal?

[selldoor]

Re: 42" Spectrincq no power

Ok good pics - looks like c64 is bulged and possibly the Big cap? may be just the camera angle.

Can you locate and test the bridge rectifier, I think I see it in Pic 2 on the heatsink
behind the yellow box with RGA404C182324 on it.





Bridge rectifier test

a) put your multimeter in diode test mode
b) put your red lead on plus + pin side and the red lead on adjacent ~ pin - record reading
c) reverse the leads - recording reading


Then repeat the test on the other two pins

b) put your black lead on negative - pin side and the red lead on adjacent ~ pin - record reading
c) reverse the leads - recording reading

Then repeat the test on the middle two pins

[budm]

Re: 42" Spectrincq no power

Where is the pictures of this FOIL cap?

[tom66]

Re: 42" Spectrincq no power

I can see some caps with domed tops. This power supply looks familiar, I think TOM have seen this before in VESTEL?

This PSU looks similar, but not identical, to the one used in certain Lexsor and Polaroid TVs - a Harwa PSU. But it is different, so it might not be identical. Mine had several bad caps too.

[multimeter]

Re: 42" Spectrincq no power

looks like samxon GF's on the outputs,rip em out !

[avaktech]

Re: 42" Spectrincq no power

Foil cap is bottom right on pic 238.

On the left you can see on the 120 connector one of the pins got burned up a bit.

[budm]

Re: 42" Spectrincq no power

That green cap C44? Do you have the value as printed on the body? It is used for snubber circuits and they do go bad due to exposing to high kick back voltage from the transformer, if it goes out, the MOSFET that drive the transformer will be damaged and it can take out the SMPS IC with it also. May be that is why the fuse blown due to BACK EMF of the transformer. You should remove it from the board and see if the body has crack or bulging out to the side. You should also see if it has leakage resistance.
See example:
http://s807.photobucket.com/albums/y...nt=badcap1.jpg

[avaktech]

Re: 42" Spectrincq no power

Well c44 seems to be nearly open, can get reading in diode mode. How do I test the SMPS? Is that this part?:TNY266PN It is included in the repair kit so I'm guessing its common for it to go.

[avaktech]

Re: 42" Spectrincq no power

c44 is 47uf 25v electrolytic.

[avaktech]

Re: 42" Spectrincq no power

Budm where you asking about the foil cap at c3? above c44? If thats the case it has nearly no resistance. It looks just like the one in your pic but its a different color. I think its a 105j400v

[budm]

Re: 42" Spectrincq no power

No, C44 is the green polyester cap at the bottom right corner of the board as you have said in pic238, see post 15. Isn't that c44 you are talking about?
in post1 " Only thing possibly fishy is a closed 400v polyester foil capacitor"