LG 42PC3D - Will Not Turn On (Standby Only)

[marckuh]

The other day, we had a big thunderstorm roll through. During that, I had the TV on. I saw some lightning strike close to the house. I thought the power went off because I didnt hear the TV anymore. I go look and the standby light is on. I press the power button and the LED goes to green, blinks 3 times, and then back to standby. When I unplug/plug, I can hear the relay click though.

I hooked up another TV and found that the HDMI port was bad on my DVR after all of this. The cable was fine.

I removed the back panel of the TV, checked for any visual signs of damage; didn't see any. I noticed that if I unplug one of the plugs going to 68719MMU20A board, the TV wil turn on, light up (blank), and then eventually turn off. Not sure what that means, if anything.

I've read a bunch of websites, but this one seems to have the most content and users who know what they are talking about. Any ideas/help would be greatly appreciated. I would like to fix the TV without spending an arm and a leg. I really don't know where to begin.

Thanks in advance.

[tom66]

Re: LG 42PC3D - Will Not Turn On (Standby Only)

Pictures would be very helpful of the power supply and main board.

Since it is stuck in standby, I'm inclined to think it is a coincidence (the primary side stuff is still good) or related to the HDMI port on your DVR. Does the DVR still work?

If the set is still under warranty, take that route.

[mj_ferry]

Re: LG 42PC3D - Will Not Turn On (Standby Only)

the board you listed that you unplug what board is it? What it sounds like that maybe that board is fried and it causes the power supply to shut down from protection. What you did unplugging the board is the start of troubleshooting. Since the dvr hdmi port is bad maybe you got a surge through your cable tv that went through the hdmi into the video main board in the tv and that could be whats fried. There should be a way to uplug everything from the powersupply board and put the powersupply in service mode and check the power outputs with nothing connected.

[PlainBill]

Re: LG 42PC3D - Will Not Turn On (Standby Only)

A few points.

The 68719MMU20A is the main board. There are a number of plugs going to it. Which plug was removed is significant.

The service manual for this set is available on Elektrotanya.

As others have mentioned, pictures help understand the problem.

It is very likely the surge from the lightning hit took out the board in the TV and also the HDMI output of the DVR. There may be other damage.

PlainBill

[cadillacman]

Re: LG 42PC3D - Will Not Turn On (Standby Only)

yeah thats scary.

I do have a working parts set of the same or simular model, ive already robbed one of the sustain boards and this set had the sparkles issue that these all get.

S if yu want a known wrking power supply and mainboard(may or may not make your set sparkle) lmk.

I would be very scared that there may be more damage you wont know about untill you replace some other parts.

[marckuh]

Re: LG 42PC3D - Will Not Turn On (Standby Only)

I took some pictures last night. Hope they help. If you want to look at the originals, I can email them.

1. Power Supply



2. Main Board 1



3. Main Board 2



4. TV Overall

[marckuh]

Re: LG 42PC3D - Will Not Turn On (Standby Only)

I think I'm just going to take a chance and buy a main board. It seems to be the logical guess, lol, considering I lost the HDMI port on the DVR.

[cadillacman]

Re: LG 42PC3D - Will Not Turn On (Standby Only)

oh wow wait nevermind i have 2 of these sets both have blown z-sustain boards and god knows what else.

Best of luck sir i hope you are able to fix it up.

Heres my thought.. you have a 50-50 shot here..

If the lightning came through the power cord, you likely have damage to everything.

If the lightning hit the cable box or came into the tv from the cable box,then you might get licky with just a mainboard.

[joste]

Re: LG 42PC3D - Will Not Turn On (Standby Only)

I think I'm just going to take a chance and buy a main board. It seems to be the logical guess, lol, considering I lost the HDMI port on the DVR.

Wait up!

Did you check for bad capacitor on the attached photo? It's hard to tell for sure, but it looks pretty much bulged to me from here. You're aware that their shiny tops should be perfectly flat with no dark stains around.

Please, take a look and let us know.

Good luck!

[cadillacman]

Re: LG 42PC3D - Will Not Turn On (Standby Only)

wow good catch man

[joste]

Re: LG 42PC3D - Will Not Turn On (Standby Only)

wow good catch man

Thanks, hope it'll work for our friend Marckuh

Waiting for news...

[marckuh]

Re: LG 42PC3D - Will Not Turn On (Standby Only)

Ok, I got home and checked out that cap and you are right, it has bulged. You have a really good eye! So do you think it's not the main board and the power supply or most likely, both boards?

[cadillacman]

Re: LG 42PC3D - Will Not Turn On (Standby Only)

who knows. Jam a cap in there first and see what ya get.

*ignore below i couldve sworn you had a bulged cap on a sustain board, but its on the ps. Replace that cap and see what u get mabye youll get lucky!*


i seem to remember even if fuses on the sustain were blown, this particular model will still power on and have sound. so you likely still have other issues if you are for sure its stuck in standby.(you can confirm by hooking up a video and audio source to see if you have sound)

WHat you could try is to unhook power connectors to both sustain boards(with no ac power!!!) and see if the set then powers up when plugged back in and power button pressed

If its now on, power back down, unplug ac power, try one sustain connected at a time untill you find which sustain board is stopping ya from powering up and go from there.

if unhooking the sustains still does not allow the set to power up, then you have other issues besides just your sustain boards.

[marckuh]

Re: LG 42PC3D - Will Not Turn On (Standby Only)

Guess who has a working TV!!!!! lol I switched out the main board and it fired right up. One thing that I noticed is that the main board has a green light on it, as well as, S/PDIF light. Those wouldn't light up on the bad board...well, the S/PDIF would light up momentarily. I am so happy...I fixed my TV for $43!!!

Thanks again for everyone's help!

[cadillacman]

Re: LG 42PC3D - Will Not Turn On (Standby Only)




congrats man!! frickin awesome!! i love happy endings.

Made your tv your bitch for only $43? feek yeah man. beats the hell out of buying a new set doesent it???

[rmoody]

Re: LG 42PC3D - Will Not Turn On (Standby Only)

I would have replaced that cap on the power supply too while I was in there. It will likely give you trouble down the road.