Dim screen LG 55LD520

[kingkiller]

Hi All,

I'm looking to troubleshoot why my LG's screen is so dim. It's probably worthwhile to mention that just before the screen decided to become much dimmer than usual, it was getting very bright, similar to a light bulb that gets very bright just before it dies. I'm not overly familiar with the internals of this TV except that they have some sort of back-light. Any tips on how I can go about isolating this issue would be much appreciated.

Thank you,

Mike

[kingkiller]

Re: Dim screen LG 55LD520

Any tips on where to begin?

[tom66]

Re: Dim screen LG 55LD520

Start by removing the cover and taking photos of the circuit boards inside.
Do you own a digital multimeter?

[kingkiller]

Re: Dim screen LG 55LD520

Start by removing the cover and taking photos of the circuit boards inside.
Do you own a digital multimeter?

Thanks, will do, and yes, I do. I actually found out after I had purchased the TV that it was from a member of this forum and he had previously repaired it. Here is a link to the thread. After I got it back to my house I plugged it in and it was making a buzzing noise that it wasn't making when I demo'd it at his house, so I took the back off. The jumper between the two boards on the left is sort of melted but apparently working, albeit not exactly shielded. I re-seated a few things and made sure that none of the wires on that jumper were touching and it worked fine...for a while. Now it's dim

https://www.badcaps.net/forum/showthread.php?p=361287

[mmartell]

Re: Dim screen LG 55LD520

Can't that jumper be purchased ?

[tom66]

Re: Dim screen LG 55LD520

I'm sure if you message that individual they will sort it out for you -- myself I always offer a 90 day warranty on any items I repair and resell.

[newtothis]

Re: Dim screen LG 55LD520

Agreed with Tom, Get the person who sold it to you to take a look.

Sounds as if there is still too much resistance which has caused the solder to go molten again.. this in turn has caused a bad connection which has resulted in the dimmed screen

[mmartell]

Re: Dim screen LG 55LD520

I'm all for getting in touch with the seller. But since the repair didn't last it seems the best solution is to replace that cable so as not to risk an unnecessary fire.

[kingkiller]

Re: Dim screen LG 55LD520

Can't that jumper be purchased ?

If it can I'm all ears, I'd definitely like to replace it.

I'm sure if you message that individual they will sort it out for you -- myself I always offer a 90 day warranty on any items I repair and resell.

I may give him a call, I still have his number, but I'd rather not trouble him. He gave me a good price and felt real bad when I called him after getting it home and it was making a buzzing noise. He offered to come by but I wound up fixing it myself.

Agreed with Tom, Get the person who sold it to you to take a look.

Sounds as if there is still too much resistance which has caused the solder to go molten again.. this in turn has caused a bad connection which has resulted in the dimmed screen

Thing is it's probably been at least 3 months since I bought it. I might give him a call but at this point I really consider it my own problem. I do have a question though. In his thread someone recommended bridging some wires. I was looking for signs of what was done but I couldn't find any. Could someone clue me in on what the fix suggested in the previous thread was? Thank you!

[newtothis]

Re: Dim screen LG 55LD520

Ok get plenty of pics of the internals, shot so we can see them all, one of each board and any connections between boards

[mmartell]

Re: Dim screen LG 55LD520

newtothis check out the pics in the link in post#4. Just the jumper area needs repair. It looks like an awful damn mess lol.

[newtothis]

Re: Dim screen LG 55LD520

Ah, seen this a few times now! Is rather common.

I'd sod the connectors off and direct solder the damn things directly... Like to see bad connections then!

[kingkiller]

Re: Dim screen LG 55LD520

Hey guys I ordered a new jumper tonight. Where are you thinking the bad/high resistance is, where the jumper socket gets soldered to the board, or with the jumper not being seated properly at the factory?

[tom66]

Re: Dim screen LG 55LD520

Definitely not being seated properly.

[kingkiller]

Re: Dim screen LG 55LD520

Great, so is the thought that replacing the jumper will resolve the issue? Is there anything I should test after replacing it to make sure it's ok?

[tom66]

Re: Dim screen LG 55LD520

Measure the voltage from end to end of the connector after the set has ran for some time.

[kingkiller]

Re: Dim screen LG 55LD520

Oof, things are looking ugly...the connector on the slave side is brown now and the master side connector was already obliterated. I have one new connector but I don't want to waste a $17 connector on something that is going to happen again. a few of the pins on the master side were loose, not sure if that's what caused the issues or if it was a result. Chicken or egg.

Is newtothis's suggestions legit? Can I actually solder 20 little wires? That would be such a pain...

[kingkiller]

Re: Dim screen LG 55LD520

[kingkiller]

Re: Dim screen LG 55LD520

[kingkiller]

Re: Dim screen LG 55LD520

Ok, new board and jumper came in today. After I replace the inverter board and seat the new jumper, what should I do to make sure this doesn't happen again? Just test resistance from board to board across the jumper?