Varistor ID??

[brmorr]

OK, helping my friend fix his Samsung Plasma TV and after opening it up and checking it out, everything looks for except a green MOV.

Appears to have markings of SCK 20100 on it. What am I looking for to replace this?? Can I get it locally at Frys or something or possibly rob one or two out of a computer power supply???

Let me know!!!!

Thanks,
Brian

[budm]

Re: Varistor ID??

You can test the TV without having MOV in place, MOV is connected between Hot and Neutral, when it is hit with the surge or sustain over voltage condition, it will conduct which will cause the main fuse to blow. So can we see the pictures to make sure it is MOV or it is NTC Thermistor.

[brmorr]

Re: Varistor ID??

Ok, I don't have the board in hand yet, but my friend tested out all of the fuses and they all tested good. Could it be that the green MOV just failed? It burned the board a little bit and and I think one other thing around it(burn marks on white square thing(sorry, don't know name). The green MOV is definitely cracked.

So, I can by pass the MOV?? Piece of wire or ?? TV currently does nothing when it is tried to be powered up. He said it worked fine one minute, turned it off and it never turned back on.

LMK!!!

Brian

[budm]

Re: Varistor ID??

If it is MOV, then you just remove it, the TV will function without it. But I need to make sure it is MOV not NTC Thermistor. I cannot tell until I see the board.

[brmorr]

Re: Varistor ID??

Here are some pics.. You can clearly see the toasted part in the pic!!!

LMK!!
Brian

[redwire]

Re: Varistor ID??

That looks like a pair of NTC thermistors, the MOV's are far left of them. I usually see the primary-side SMPS shorts and overloads the NTC's. The fuse doesn't pop.
So replacing the NTC might not fix it, you have to check the mosfets too.
My concern is the PCB is carbonized due to the heat and the high-voltages there could carbon track, as the fiberglass becomes conductive once burnt.

Budm, I've seen a few (roasted NTC) pics like this posted here on Badcaps and feel like forwarding them to the UL, as this isn't far from putting a set on fire. What do you think?

[brmorr]

Re: Varistor ID??

Here is the backside of the board!!!

What shorts that cause these to fry like this???

Brian

[redwire]

Re: Varistor ID??

The NTC's are supposed to limit inrush current when the DC link capacitors charge.
The power supply starts up, and then relay RLQ801S is asserted which bypasses (shorts) the NTC's. If the PSU is shorted, the NTC's just sit and roast. The mosfets to check are the ones along the two heatsinks near the NTC's.

I would price out a replacement board, Samsung aren't too expensive (Google the p/n). Troubleshooting this is difficult due to the high voltage and narrowing down where the overload is. I'm not sure of your experience level but I think it would be more work than changing the burnt NTC.

[TadTV]

Re: Varistor ID??

I have a cracked one as well. Has anyone found a place to get them and the item number or values? Full power boards are not available for less than $200 now. Have to try to fix this first.

[R_J]

Re: Varistor ID??

I have seen this in other sets where the relay contacts are bad and all the current continues to flow through the icl causing it to burn up.
SCK 20100 10 ohm 5.5 amp
Digikey has 10 ohm 6 amp rated ones SL12 10006
http://www.digikey.com/product-searc...=0&pageSize=25

[Lloyd6202]

Re: Varistor ID??

Does anyone know where i can find the relay for RLQ801S AND RLQBO2S.they both were burned up

[R_J]

Re: Varistor ID??

You might have better luck posting the numbers from the relays, not their board location.
Looks like the number is OZT-SS-112LM I think this should work OZ-SS-112LM1,200, https://www.digikey.com/product-deta...671-ND/1427511

OZT = TV-8 Rating PC Board Terminals

[PeteS in CA]

Re: Varistor ID??

Putting two possibilities suggested by tow different people, either some MOSFETs downstream from the thermistors shorted, causing destruction, or the relay across the fried thermistor failed to close, causing the thermistor to conduct the full current and frying it.

The PCB damage is due to the thermistor overheating. The fact that the board is so damaged means the thermistor was really hot for a fairly long time. From that I would infer that the relay is the problem (but I would still make sure downstream MOSFETs aren't shorted).

[Lloyd6202]

Re: Varistor ID??

Thats awesome thank u so much..ya they were badly burned i couldnt make out the numbers...