LG 42LK520-UA Sound, but no Picture

[pauldow]

On this television the red standby LED is on when plugged in. It turns blue when I press the power button. The backlight is on. I occasionally must select an analog TV station, and I get the white noise of a blank channel. The volume control works.
The problem is that there's no image on the screen.

I did a D'oh! situation with it when I was testing the power supply. I accidentally shorted a couple of lines. The TV was completely dead then. I tried Jimmy's repair kit for this model, but it didn't help. I ordered a replacement power supply, and it's back to the original issue of no image.

I checked the fuse on the T-Con.

Does anyone have a suggestion on what to look for next?

Thanks,
Paul

[ReeceyBurger123]

Re: LG 42LK520-UA Sound, but no Picture

Disconnected one side of the panel and seen if the other works ?

[pauldow]

Re: LG 42LK520-UA Sound, but no Picture

Hi,

Thank you for the reply.
Sorry I didn't get back to you quicker. I had the reply notice subscription set to "daily". I changed it to immediate.

I disconnected the flat cables at the top of the T-Con board, one at a time. There was still no image on the display.

From the holes in the back of the chassis, it looks like the back lights are pretty evenly on. It's tough to see if there may be one or two out.

I saw the other thread here regarding this television, and it gave instructions to perform a reset. Since I can't see anything on the screen, I can't use the remote to try that.

Do you have any other suggestions?
Paul

[pauldow]

Re: LG 42LK520-UA Sound, but no Picture

I watched some Youtubes on this subject, and saw that some people had my problem when some backlights were out.
I thought this TV had LED backlights, but my disassembly showed that they are CCFLs.
One of them is out. Would just a single one being out be enough to put a halt to the processor from doing its picture making job?

Thanks

[budm]

Re: LG 42LK520-UA Sound, but no Picture

I watched some Youtubes on this subject, and saw that some people had my problem when some backlights were out.
I thought this TV had LED backlights, but my disassembly showed that they are CCFLs.
One of them is out. Would just a single one being out be enough to put a halt to the processor from doing its picture making job?

Thanks

Yes, it only take one bad lamp or one bad lamp connection to trip the protection circuit.

[pauldow]

Re: LG 42LK520-UA Sound, but no Picture

Well, I purchased a replacement CCFL for the one that's out.
The one I got has wires on the ends. The original ones have a tube about 5/16" X 1 1/4" that snaps into a clip on each end.
I tried reusing the old ones, but I overheated it a bit (well, a lot.) As I pulled out the glass, it stretched turning it into a fiber optic line.

Then my "super genius (R)" capability took over.
I went to a hardware store and bought a couple roll (tension) pins. Cleaned them, heated them, filled them with solder, and stuck in the CCFL wire.
When I installed it, only the new one lit instead of that one being the only one out.
When I remove the new one, it goes back to all the other tubes lighting.

Unfortunately, I seem to have used up all my brain power, and I'm at the "What the...?" phase.

Was there something inside the end connector, or could this be a different type of CCFL?

Thanks again for any help,
Paul

[budm]

Re: LG 42LK520-UA Sound, but no Picture

Your panel uses EEFL type not CCFL.
The lamps are connected in parallel without ballast capacitor for each lamp like CCFL.
Look up the spec for your LCD panel.

[pauldow]

Re: LG 42LK520-UA Sound, but no Picture

I think everyone around here knows who the real super genius is around here.

Thanks Bud

It's back to the thin glass tube store for me.