Lg 42ld550

[Bigredram87]

Hi guys I just picked up a 42" LG 42LD550. the Tv has sound but has no picture. Ive been reading up on other peoples similiar issues and I was curious how I can confirm which board needs replaced. Ive heard a lot of people saying its the main board but Im also confused on how to troubleshoot inverter boards. Also I figured I would check power(and fuses) at the power supply board to verify the correct power was going to the Main board. Where would be a good place to start on this TV. Thanks so much when I get the TV home I am going to take pictures of all the boards.

[tom66]

Re: Lg 42ld550

Check fault: dark room, screen glowing or not glowing?

[Bigredram87]

Re: Lg 42ld550

Yes the tv does glow

[tom66]

Re: Lg 42ld550

OK, at this point, you'll have to take the set apart and provide good clear photos: one of the overall TV layout, and one of each major circuit board you can see.

[Bigredram87]

Re: Lg 42ld550

So I may have been took . So I opened it up to show you some pics and I noticed the two inverter doors were unplugged. I plugged them in and now the situation has changed. Is the tv done ?

[mmartell]

Re: Lg 42ld550

Interesting. As a lay person I'd be surprised if that's a bad panel, maybe a tcon issue ?

[Bigredram87]

Re: Lg 42ld550

Oh really? I thought it was a bad screen I will proceed with taking pictures of boards than

[Bigredram87]

Re: Lg 42ld550

[Bigredram87]

Re: Lg 42ld550

Heres some more.... So Ive been looking at some other tcon boards and Im kind of confused. is the tcon board and the main board combined on this unit or do the 2 separate ribbon cables run to 2 separate tcon boards?

[Bigredram87]

Re: Lg 42ld550

[mmartell]

Re: Lg 42ld550

Well I said "as a lay person", I'd wait for others to chime in.

[newtothis]

Re: Lg 42ld550

Unplug a ribbon cable at a time, power up the set... What does the screen show?

[Bigredram87]

Re: Lg 42ld550

Ok I will try this as soon as I get home from work.

[Bigredram87]

Re: Lg 42ld550

So i am going to go do this test in about an hour when I get home, but Im curious what results are you expecting and/or what would a few different results mean? Or even what would a correctly working TV do with unplugging a ribbon cable?

[tom66]

Re: Lg 42ld550

Screen should be black with a slight glow.

[Bigredram87]

Re: Lg 42ld550

If the screen is black with a slight glow does that mean the lcd panel is good? Thanks

[Bigredram87]

Re: Lg 42ld550

Ok with both ribbon cables unplugged the screen does just glow. Please advise on next step

[budm]

Re: Lg 42ld550

The backlights are working, need to check the DC voltage on the surface mounted fuse on the T-CON board next, see if you do get either 5V or 12V on both ends of the fuse with chassis as the ground ref. point. More likey to have voltage, the way the picture on the screen looks, it is sure strange to me also, never seen on looking like that. Post the pictures of the T-CON board. Put the ribbon cable back in one at a time to see what you get on the screen with each cable connected.

[Bigredram87]

Re: Lg 42ld550

Ok I am familiar with surface mount parts but from looking at other posts I can't figure out which one is my tcon board?some posts say its behind the metal? Or is it the 2 small boards at the top

[Bigredram87]

Re: Lg 42ld550

1 ribbon cable disconnected