Samsung LE26A457C1D Power problem, It Banged

[aar5384]

Heres another one of the Tv's ive been having a play with. Its one of the collection from the local tip that one of my friends gives me for a couple of quid who works there.

The tv wouldnt turn on, I checked the fuse in this one! There was no lights or nothing happening. I looked at the mainboard and couldnt see any bulging or leaky caps by eye and just out of curiosity i thought id try changing the fuse on the power board BN44-00214A, However I didnt have any ceramic ones to hand and so just popped a glass 3 amp one in.

Plugged it in and bang! Crackle! the fuse exploded shattering it.

Had another look and the little blue disc cap ( i think ) at CM810 appears to have blown or shorted with a rail J839 and made one of the legs of the cap burn off.

So, looking for ideas..

Help

[selldoor]

Re: Samsung LE26A457C1D Power problem, It Banged

Hope you have plenty time and patience as I think your first major task may be to get that brown glue off. £It looks like the sort that becomes conductive..Try softening it with isopropyl alcohol the just carefully scrape away at it

When you tire of that - in around 3 minutes perhaps try and find the threads that say how to use a lightbulb to reduce current while testing.
It is also on the www


heres 1

https://www.badcaps.net/forum/showth...t+bulb+current

[aar5384]

Re: Samsung LE26A457C1D Power problem, It Banged

It sounds like its not going to be as easy as i thought.

The cap that shorted out on the rail, lets say i replace that in a way that it doesnt short out on the rail next to it, fit a new fuse to the board, whats the chances of it going bang straight away and scaring the crap outa me?

[aar5384]

Re: Samsung LE26A457C1D Power problem, It Banged

Well i got a little board so i removed the glue stuff, it just appears the cap shorted its leg out on the bridge wire, so i resoldered its leg back into place and now im just a little on edge wether to pop a fuse into it and turn it on incase it goes bang and sets on fire ?!?

[selldoor]

Re: Samsung LE26A457C1D Power problem, It Banged

Have you not got an old type filament bulb 75 or 100w - you just need connect it on the mains positive input and it will save any bangs.
Reading lamp / desk light/ inspection light
If the bulb lights bright it means there is probably a short on the set.

Otherwise stand well back and shield yourself especially eyes.

[selldoor]

Re: Samsung LE26A457C1D Power problem, It Banged

I suppose you could do some checks before.
Test the Bridge rectifier and test the BIG Cap to see if its shorted.
Make sure its discharged first

[aar5384]

Re: Samsung LE26A457C1D Power problem, It Banged

Ive done a test on the bridge rectifier and across the centre 2 pins i get a reading with positvie on the left and negative on the right of the 2 centre pins , am i right in believing that i should not have any reading at all, in diode mode on multimeter with part out of board

[multimeter]

Re: Samsung LE26A457C1D Power problem, It Banged

Ive done a test on the bridge rectifier and across the centre 2 pins i get a reading with positvie on the left and negative on the right of the 2 centre pins , am i right in believing that i should not have any reading at all, in diode mode on multimeter with part out of board

you shouldnt get and reading either way on those 2 pins AC AC.

[aar5384]

Re: Samsung LE26A457C1D Power problem, It Banged

you shouldnt get and reading either way on those 2 pins AC AC.

Im getting a reading of 639. Would it cause further damage along the line other than blow the fuse do you think? I did take out the big cap and got a reading out of it to what i cannot remember though it was the other day.

Otherwise, i shall order a part and refit and fire it up and stand well back clenching my eyes lol

[budm]

Re: Samsung LE26A457C1D Power problem, It Banged

Remove ALL the glue, I can see burnt section on the blue cap which is exposed to high voltage. Also seed dark brown glue on the TO-220 device. The glues are conductive and corrosive.

[selldoor]

Re: Samsung LE26A457C1D Power problem, It Banged

If that cap you "mended" is a blue ceramic high voltage cap I would get a new one when you order the bridge. It is unlikely to hold up.

[aar5384]

Re: Samsung LE26A457C1D Power problem, It Banged

Ive removed as much glue as i can and made sure all legs are free of the stuff. Im looking for the TO-220 device and struggling to find it, can you give me a hint?

For the capacitor i "mended" it was a bit of a bodge when i got bored and i have now removed it, its a 1kv 2.2nf according to the schematics and cpc had something looking very different http://cpc.farnell.com/jsp/search/pr...&Ntt=1kv+2.2nf but i think fleabay has some unless you know a good supplier in the uk?

[selldoor]

Re: Samsung LE26A457C1D Power problem, It Banged

TO-220 - from main input connector diagonally to the right - just above the blue cap.

EDIT how about this?

http://cpc.farnell.com/murata/debf33...age/dp/CA05022

[aar5384]

Re: Samsung LE26A457C1D Power problem, It Banged

TO-220 - from main input connector diagonally to the right - just above the blue cap.

Nope now im completely lost lol

[selldoor]

Re: Samsung LE26A457C1D Power problem, It Banged

Nope now im completely lost lol

Oh dear.

Did you see my edit

[budm]

Re: Samsung LE26A457C1D Power problem, It Banged

The 2.2nf cap is the blue rectangular cap? the one with burnt glue is the blue ceramic high voltage cap to the left of the heat sink on the bottom right of the board.

[aar5384]

Re: Samsung LE26A457C1D Power problem, It Banged

Ohhhh i was looking at that but all i got on that is QB802 and on the sheet it says 80v 4A thats proberbly why i didnt understand. Im not up on component names without a bit of lookin up sorry but thanks

[aar5384]

Re: Samsung LE26A457C1D Power problem, It Banged

The 2.2nf cap is the blue rectangular cap? the one with burnt glue is the blue ceramic high voltage cap to the left of the heat sink on the bottom right of the board.

Looks fine that one it was just covered in glue lol The one i thought you were talking of is the lil blue disc cap just underneath the big cap

[aar5384]

Re: Samsung LE26A457C1D Power problem, It Banged

TO-220 - from main input connector diagonally to the right - just above the blue cap.

EDIT how about this?

http://cpc.farnell.com/murata/debf33...age/dp/CA05022

Yes! I saw this the other day while looking a bit more in depth i just passed on it thinking maybe its different for saying 1000v instead of 1kv when they are both the same thing :/

[aar5384]

Re: Samsung LE26A457C1D Power problem, It Banged

Okay, new parts have come, new bridge rectifier and little blue cap along with a bunch of new fuses.

Fitted them all in well and gave it a whirl, standing well back expecting another bang pop fizzle, and nothing happened, so i checked for current and theres no power coming in, suspecting blown fuse in plug i changed it and still nothing, checked the fuses and all had blown again. So i checked the soldering and lines for making sure theres nothing shorted out and all is clear and im stuck what i should check next

Any ideas for me?