LG 50PA5500 no picture

[graveboy81]

Re: LG 50PA5500 no picture

OK. I'll check. hopefully it is the power supply.

[graveboy81]

Re: LG 50PA5500 no picture

should i be using the remote to turn the tv on or does it even matter? I saw some videos of people using remotes to turn the tv on instead of the buttons.

[tom66]

Re: LG 50PA5500 no picture

It doesn't matter, just as long as the TV is "on" i.e. power light changes and it produces sound (if connected to the correct input)

[graveboy81]

Re: LG 50PA5500 no picture

Just a thought...could a bad solder job on that c802 have played a factor in my tv not fully powering up?

[tom66]

Re: LG 50PA5500 no picture

Before jumping to conclusions check voltages first.
it's much faster and you can rule out faults straight away with just a few checks.

[graveboy81]

Re: LG 50PA5500 no picture

Well, i think i ruined the main logic board while checking the power supply! I was checking the va on the power supply when i heard a pop. Then the tv started clicking and smoke came from what looks like the main logic board because there use to be a green light flashing then the tv shut off. Then i powered the tv on again and the green light doesn't flash at all. Cant get a reading from the zbias and when i check the y sus it reads -55 when it should be -190. Now after 20 minutes or so, the tv automatically shuts off!

[tom66]

Re: LG 50PA5500 no picture

More likely you killed the panel, the logic board has no connection to Vs/Va except through the address buffers. Ah well, good lesson, be more careful next time.

[graveboy81]

Re: LG 50PA5500 no picture

How did i kill the panel? What are the address buffers?

[tom66]

Re: LG 50PA5500 no picture

The address buffers run along the bottom of the panel and they are connected to the control board. I would suspect the panel to be damaged as that is the only way testing Va could cause failure of the control board (perhaps via having the meter on the wrong range, like on mA instead of V.)

[graveboy81]

Re: LG 50PA5500 no picture

This my tv that board right under the psu is the board im talking about. It use to flash green,now it doesn't.

[graveboy81]

Re: LG 50PA5500 no picture

I had it on V the whole time. I don't know tom66, i refuse to believe that panel is shot because of that board going out. Changing that board has to be done because it has ribbons that run to the y and z -sus and logic board.

[tom66]

Re: LG 50PA5500 no picture

You can try installing a new control board then and see. It's just worrying me that you have shorted or tested something wrong and caused some damaged. I can't see how that board would go "bang" any other way. Could your probe have slipped while testing?

[graveboy81]

Re: LG 50PA5500 no picture

The pin close to the va is this 5v pin. It was strange to me too. Before the va problem, I may have to change the y -sus too because after i plugged the upper buffer board back up, i plugged in the power coard and heard a small pop where the y-sus and upper board meet.

[tom66]

Re: LG 50PA5500 no picture

If Va and 5V is shorted, wow, that would kill so many parts. Va is 55V. 5V is... well, 5V. The panel, Y-sus, Z-sus, control and possibly main board would all be destroyed. I hope that is not the case, but it is the only explanation right now.

[newtothis]

Re: LG 50PA5500 no picture

Gotta agree with Tom... If you shorted the Va to 5v you have really fried the set!

IF that is what happened I would cut your losses

[Hamie]

Re: LG 50PA5500 no picture

Oh dear.

[graveboy81]

Re: LG 50PA5500 no picture

But i still get a correct voltage reading from the va and 5v.
This is where the smoke came main logic control board. It has a small chip at what looks to be IC252.

[tom66]

Re: LG 50PA5500 no picture

Power supplies are pretty tolerant - of all things that would survive that abuse that is more likely than anything.

I would say that if you want to try a new control board go for it, but the only thing that could cause that IC to burn from testing, AFAIK, is a short from Va or Vs to 5V.

[graveboy81]

Re: LG 50PA5500 no picture

Afaik?

[tom66]

Re: LG 50PA5500 no picture

"As far as I know"