Samsung LE37B530P7W 37" dead power supply

[dymardo]

I found a 22" LG TV in the garbage two weeks ago and fixed it by replacing dry caps. I got excited and decided to fix other TVs. It's difficult to source broken tech for free around here, so I bought a 37" Samsung next. The seller was nice enough to include another smaller broken TV and delivered them to my home.

The small TV has an external power supply and can't turn on (light goes from red to yellow for a second, then back to red), but my biggest issue is with the big TV:

I opened it up and turns out it was already opened. There were 2 fuses installed, one of them was burnt. I replaced the dead one with another working fuse, closed the lid and saw a flash of light when plugging the cable.

Turns out, not all fuses are the same. There's slow and fast fuses, plus the capacity and voltage. The old owner had tried putting two 1A fast fuses in. I added a fast 1.6A and it made the other original 1A fuse die (it looked like a dish left unatended in the oven).

There's the right value printed on the board: T3.15AH250V & T5AH250V.

It would be really easy to fix, but I noticed that some components look burned. I don't know if the old owner did this or it was me, since the upper fuse didn't burn. Theres CM806 that is completely melted. Others, including some jumpers, have a dark spot around the hole. I tested the resistance of the two huge capacitors but they appear to be dead and have dark spot around the negative terminal. I should get a proper capacitance tester to be sure.

Should I try replacing all the components and see what happens? If the TV hadn't been opened, I would be 100% sure that the CPU and TCON boards work.

The two TVs cost me 20€. A new power board should be around 50-60€. The bigger TV sells for 100€. The smaller must be around 20€. I can focus on the small one to see if I can recover what I spent.

[dick_barton]

There's a service manual here but I don't know if it's of any use to you.
https://www.manualslib.com/download/...53-Series.html

[nomoresonys]

Post some clear straight on pictures of each board and one of the whole back as to see how they are all connected.

[dymardo]

Originally Posted by dick_barton

There's a service manual here but I don't know if it's of any use to you.
https://www.manualslib.com/download/...53-Series.html

Thank you! I reviewed this same document and I can't find the components. They have different codes to the ones I have on my psu.

Originally Posted by nomoresonys

Post some clear straight on pictures of each board and one of the whole back as to see how they are all connected.

I've uploaded some pictures. Note that one component is completely melted, while others have a darker pcb area around the leg. Thank you for your help!

[R_J]

Yes CM806 disc capacitor is shorted. The ic nect to it might be bad as well ICM801, what is the number on the ic as well as the cap if it is still there on the side that is good.
The cap CM806 is usually has a 1KV rating but is best replaced by one with a 2KV rating.

[neilc6]

Blown fuses will always be caused by shorted component usually FETs and diodes. You should be able to measure the short on the component side of the fuse to ground.

[nomoresonys]

Maybe build a simple dim bulb tester to use, (many examples on youtube) so you are not blowing up fuses and components, replace CM806 and check the surrounding components, really hard to tell what happened, may have a problem may have just gotten a surge that blew the fuse and a wrong replacement fuse blew up the cap. The dim bulb tester will light up bright if there's a problem instead of blowing all your new fuses and such.

[R_J]

This snubber cap (CM806) is a common failure on these samsung boards, other models have the same problem, the cap shorts and the fuse opens. Sometimes the ic's output fet also shorts after the cap shorts and blows open.
The ic might be a STR-W6252 or similar The cap might be a 47pf 1kv

[nomoresonys]

Ok, so hopefully the cap just blew up and that's all that's wrong, fingers crossed.

[R_J]

But someone else was already in it and installed fuses so what else did they try? cross toes as well.

[nomoresonys]

[dymardo]

@R_J I'll look into it. Thanks.

@neilc6 That is a great idea. I'll see if the fuses are grounded.

@nomoresonys You mean connecting a incandescent bulb in series with the TV? My dad suggested doing that on my previous fix. I need to find one for sale. At lest 60W. They're difficult to find here in town since everything is LED now.

Thanks for your help gents/ladies! I'm afraid other components may be damaged, because of those dark marks on the PCB. The huge caps seem to work, but I can't measure the exact capacity.

[nomoresonys]

"@nomoresonys You mean connecting a incandescent bulb in series with the TV? My dad suggested doing that on my previous fix. I need to find one for sale. At lest 60W. They're difficult to find here in town since everything is LED now." Yes, I don't see a lot of incandescent bulbs over here any more either.

[dick_barton]

I would check out the IC behind the blown capacitor. Cannot see all it's number ICM8xxx.