Lg 50pk790

[Missy]

My tv (model in thread title) has all of a sudden lost picture and sound. I'm quite compitant fixing pcb's etc as I worked in electronics but I have no testing equipment 😔😔. There are no sign signs of blown caps or resistors etc.

It was fine last night, there she been no signs of anything suspicious building up problems. It literally turned on and there's was no picture, the sound could only Be described as satanic talking (lol) for a few seconds then nothing.

I can turn the tv on and the standby light goes from red to blue, it goes bright like it's going to the logo but nothing. It goes dark and it clicks back to red, I hear the clicks when it goes on and off.

Is it the psu or the main board? I've repaired lots of Samsung LCD's but never a plasma.

Thanks in advance

Sarah x

[Hamie]

Re: Lg 50pk790

So to clarify, the screen lights up for a second then goes back to standby?

[Missy]

Re: Lg 50pk790

It lights up brighter, like it's turning on then it goes dark again but the tv is still on. I then press the standby button and it clicks ok like its going off.

[Hamie]

Re: Lg 50pk790

Probably mainboard.
You can run test patterns on this model with mainboard disconnected.

On the control board look for 2 holes marked ext_auto_gen. Alternatively 2 holes beside r51 and r52.

Connect the 2 holes with a piece of wire (paperclip etc)

Finally disconnect the LVDS cable.

Turn on the tv.

[Missy]

Re: Lg 50pk790

What would I be looking for?

[Hamie]

Re: Lg 50pk790

If you correctly have the jumperwire in place you should have clear test patterns on screen.

[Missy]

Re: Lg 50pk790

And if that's there then what's it likely to be? If it's not there then what's the problem?

[Hamie]

Re: Lg 50pk790

If you have test patterns you have a faulty mainboard.

If not you have a fault somewhere else.

[Missy]

Re: Lg 50pk790

Ok thank you.

[Missy]

Re: Lg 50pk790

Ok changed the little main board but the problem still persists. Please help as I can do without buying a new tv just before Xmas.

Are we talking psu board fault?

[Missy]

Re: Lg 50pk790

Ok think someone on another site told me the wrong boards. I was told to replace main board and he showed me the little one with the square surface mounted chip. But now I'm thinking he meant the one with the hdmi ports on yes???

[Packard93]

Re: Lg 50pk790

hmm It could be inverter or power supply.

[Packard93]

Re: Lg 50pk790

really should get a cheap multimeter

[Packard93]

Re: Lg 50pk790

Give me a description of everything that happens as you turn on the set

[Missy]

Re: Lg 50pk790

I'm thinking psu, that was my gut instinct but he said replace that.

[Packard93]

Re: Lg 50pk790

yes the mainboard is hdmi port .

[Missy]

Re: Lg 50pk790

OMG! Lol thank you x

[Packard93]

Re: Lg 50pk790

Search bing for your model and look under video Look for video that has your issue to resolve your problem. Lots info other there fo fix this tv. I guarantee you can fix it .

[Missy]

Re: Lg 50pk790

Give me a description of everything that happens as you turn on the set

Ok I turn it on either by the tv button or the remote and it turns on, clicks as normal and lights up like it's going to go to the logo page But then goes black. The standby button lights up blue as if on and fades in and and out then goes black. If I turn it off it does go red to standby.

[Missy]

Re: Lg 50pk790

Search bing for your model and look under video Look for video that has your issue to resolve your problem. Lots info other there fo fix this tv. I guarantee you can fix it .

I have googled before here and it's either sound not working or picture not both.