LG 55UH7650-UA needs a capacitor!

[x_orange90_x]

I got an LG 55UH7650-UA that I could hear popping when I plugged it in. After opening it up I found a ceramic disc cap that's completely obliterated. I can't find a schematic for the board, and the cap is obviously unreadable. I read someone else on another forum ask about the same cap, or so it appeared. Their board however looked different and the cap was in a different location on the board.

I have junk power boards with a bunch of these style caps, but most are 1kV or 250v. How can I be sure I get the right rated cap if I don't have a schematic?

The board in my TV is EAY64210702.

[alfatv]

Re: LG 55UH7650-UA needs a capacitor!

1kV is voltage rating, most likely you need that type, but you also need capacitance, somewhere around 220-470pF. Take a look at blue cap in 1st picture, very likely it's the same type. Also check both transistors mounted on a heatsink.

[x_orange90_x]

Re: LG 55UH7650-UA needs a capacitor!

Ok that's a good idea. I'll look at that other one. Are you suspecting damage to those transistors as well?

[alfatv]

Re: LG 55UH7650-UA needs a capacitor!

. Are you suspecting damage to those transistors as well?

Yes. The damage would be short circuit between 2nd and 3rd pin.

[lotas]

Re: LG 55UH7650-UA needs a capacitor!

Transistors don’t always burn out, sometimes you’re lucky and only the capacitor and fuse burn out. Check the resistance of these mosfets and the two diodes on the back of the board.

[x_orange90_x]

Re: LG 55UH7650-UA needs a capacitor!

I replaced the bad cap last night but still no power. The surrounding components may be bad. Still need to get my multimeter to check those.

[slybunda]

Re: LG 55UH7650-UA needs a capacitor!

zoomed in on those 2 pink resistors, one looks like its gone out of shape.

[x_orange90_x]

Re: LG 55UH7650-UA needs a capacitor!

zoomed in on those 2 pink resistors, one looks like its gone out of shape.

Yes I seen that. It's lumpy and rough looking.

[EazyBone]

Re: LG 55UH7650-UA needs a capacitor!

What is the purpose of that paste on the blue cap? I know certain size caps need to be glued down but those blue caps don't fit that. Why is it actually there? Anyone know

[x_orange90_x]

Re: LG 55UH7650-UA needs a capacitor!

What is the purpose of that paste on the blue cap? I know certain size caps need to be glued down but those blue caps don't fit that. Why is it actually there? Anyone know

I'm thinking it's either there to protect them from heat coming off surrounding components, or to pull heat off of themselves? I'm trying to decipher the color codes of those resistors but the middle stripe is confusing me. It clearly looks silver but according to the chart it can't be silver, but grey instead. Also I don't know what that little black component is under the goop by my finger. There is no writing on it 😒

[vinceroger69]

Re: LG 55UH7650-UA needs a capacitor!

I'm thinking it's either there to protect them from heat coming off surrounding components, or to pull heat off of themselves? I'm trying to decipher the color codes of those resistors but the middle stripe is confusing me. It clearly looks silver but according to the chart it can't be silver, but grey instead. Also I don't know what that little black component is under the goop by my finger. There is no writing on it 😒

The black thing is a inductor.

[lotas]

Re: LG 55UH7650-UA needs a capacitor!

I I'm trying to decipher the color codes of those resistors but the middle stripe is confusing me. It clearly looks silver but according to the chart it can't be silver, but grey instead. 😒

These resistors are wirewound, low resistance 0.15 Ohm 1%.

[lotas]

Re: LG 55UH7650-UA needs a capacitor!

I replaced the bad cap last night but still no power. The surrounding components may be bad. Still need to get my multimeter to check those.

Have you checked the fuses?

[x_orange90_x]

Re: LG 55UH7650-UA needs a capacitor!

Have you checked the fuses?

No I haven't. They don't appear burned or anything, but they are the white ones, not glass, so the inside may be a different story. I imagine they are ok because the bad cap was still sparking before I replaced it. If the fuses were blown the power wouldn't make it over to that cap, right? Btw there are two fuses on this board.

[lotas]

Re: LG 55UH7650-UA needs a capacitor!

If it sparked, it means it was shorted, then this fuse could have burned out; you can simply check it with a multimeter.

[x_orange90_x]

Re: LG 55UH7650-UA needs a capacitor!

If it sparked, it means it was shorted, then this fuse could have burned out; you can simply check it with a multimeter.

I'll check that tonight. That would be great if that was the issue! So the fuse is further in the circuit than the cap that shorted?

[diif]

Re: LG 55UH7650-UA needs a capacitor!

What is the purpose of that paste on the blue cap? I know certain size caps need to be glued down but those blue caps don't fit that. Why is it actually there? Anyone know

It's being used as insulation.

[x_orange90_x]

Re: LG 55UH7650-UA needs a capacitor!

Unfortunately I can't find my multimeter to test anything ��

What is more likey to be bad? The fuse, or the transistors? Or maybe all of them? I have some donor boards that may have the right transistors.

[lotas]

Re: LG 55UH7650-UA needs a capacitor!

How do you repair equipment (TVs) without a multimeter?

[x_orange90_x]

Re: LG 55UH7650-UA needs a capacitor!

How do you repair equipment (TVs) without a multimeter?

😆 I haven't needed to use it until recently. Last time I used it was just before my basement flooded, so I think it was misplaced after the cleanup. I have an idea now where it may be though.