LG42lg50 UG power on and off

[Stormyme]

I am about to order a new power supply for my LG 42 TV and wanted to get a second opinion before I do. The problem I am having is , I recently hooked up a PS3 to my tv and after a couple months the tv started to power down and flash on and off with "No signal". Occasionally it would start up after being shut down as well. I replaced the power cord and HDMI cable in case that had anything to do with it. I also did a reset. From what I have read all over it sounds like its the power supply. I have attached a few snapshots and an AVI of what it is currently doing. The AVI is dark because I wanted you to see the lights on the tv lol The first jpg shows model of tv. Does this sound like a power supply issue? Can I test the boards to narrow down which one?

I guess I can't upload the avi. I am trying to improve the pictures. It is 4 am here though, so 1 at a time lol

[martyparish]

Re: LG42lg50 UG power on and off

Does it atually "shut down" or is it just losing the signal? If it's flashing "no signal" it is not shut down.

Have you tried other input sources? (other hdmi port, rgb, coax)

Let's see a pic of the whole backside of the TV please.

IMO this sounds like it could be a main board issue.

[Stormyme]

Re: LG42lg50 UG power on and off

Thank you for responding

It goes into standby mode for a second then flashes "no signal" and continues to do that. I switched HDMI ports and it fixed it for a day, then it did the same thing. When I would hold the power button down on the tv for 5 seconds, it would fix it for about an hour. I felt the back of the tv for overheating and nothing felt warm. I turned off the PS3 and set the input to antenna and that worked for a couple hours.

Its a very large tv, I hope these pictures are what you were after. I had to back a distance to get the whole thing in the window

[dick_barton]

Re: LG42lg50 UG power on and off

What are the voltage readings on the edge connector? I can't make out what the board number is but it's alongside the 24V supply connector.

[Stormyme]

Re: LG42lg50 UG power on and off

Brace yourselves for some vintage, but can I use my fathers old meter for this? see picture below. If so can you refresh my memory on where the red and black wands get plugged into? lol Sorry it has been a while since I have used it.

[Stormyme]

Re: LG42lg50 UG power on and off

Which connector were you wanting tested? I have attached closer images.

[Stormyme]

Re: LG42lg50 UG power on and off

I think rather than wait for my daily reply, I would rather order the boards I need. Can someone tell me which two boards cover the symptoms my TV is experiencing?

Thank you very much in advance.

[dick_barton]

Re: LG42lg50 UG power on and off

Your power supply board shown on the 1st picture right hand side has connectors. Top left and top right. Normally they have a legend along side saying what the pins are and / or what voltage should be on each pin.
If you can test those connections it may give a clue as to what the problem is.

Service manual available for download:-
http://www.electronica-pt.com/esquem...tartdown/7990/

[martyparish]

Re: LG42lg50 UG power on and off

Actually it looks like it could be an issue with the PS3. See here

http://www.cnet.com/forums/discussio...400-tv-621126/

ton of info here
https://www.google.com/search?num=20...54.0bbPDeimCLE

They say "unplug all cables including mains plug from wall for ten minutes". Worth a try I suppose???

[Stormyme]

Re: LG42lg50 UG power on and off

Before I took the back off,it sat unplugged from everything for a day or so. So before I removed the back I plugged in the power cord and the same problem remained. It went into stand by mode immediately. What I do find interesting in that thread you posted is this part.

"LG service guy visited, he informed that HDMI had some spike and so the Motherboard needs to be changed and that is the only option. Mother board changed and all back to normal. I have a Android media player connected and now its HDMI is not working, so the service guy adviced the spike might caused by the media player, and so I disconnected the media player as the HDMI from the media player is not working now."

So which one is the Motherboard? The T-Con or Inverter?

I was hoping you had a guide for connector pin testing but I do not see one. Where does the black lead connect to when testing the pins with the red lead? lol

[budm]

Re: LG42lg50 UG power on and off

http://www.shopjimmy.com/catalogsear...t/?q=LG+42lg50

There are more than one model/version of the main board.

[Stormyme]

Re: LG42lg50 UG power on and off

So the inverter board is the board they are calling the motherboard? If so is the number I have circled in my picture, the correct part number on my board?

ShopJimmy is out of stock on these. I see some on Ebay but not sure if I want to risk a random seller. Do any of you have one in your "Junk pile" lol

[budm]

Re: LG42lg50 UG power on and off

Example of main board (mother board if you want to call that) where HDMI circuits are and other inputs.
http://www.shopjimmy.com/lg-ebu49009...ua-bushljm.htm

Inverter board is Inverter board.
Did you look at the link to SJ?

[dick_barton]

Re: LG42lg50 UG power on and off

Black lead on metal chassis. Red lead to read dc voltages on connector.

[budm]

Re: LG42lg50 UG power on and off

I hope he is not going to use that Old Micronta meter with 1000 Ohms per Volt.

[Stormyme]

Re: LG42lg50 UG power on and off

I hope he is not going to use that Old Micronta meter with 1000 Ohms per Volt.

She won't now that you said something I have my sister bringing hers over tonight.

[Stormyme]

Re: LG42lg50 UG power on and off

Inverter board is Inverter board.
Did you look at the link to SJ?

Yes I did and it took me to a page of inverter boards.

I did not know there was another board hiding under these three I see.

Thank you for clearing that up.

[Stormyme]

Re: LG42lg50 UG power on and off

Black lead on metal chassis. Red lead to read dc voltages on connector.

Thank you so much. I know these little questions are irritating and I am trying to minimize how many I ask lol

I appreciate all you guys and the help you are giving me. I think I saw a donate button on the home page. I will be using it when this is over.

[Stormyme]

Re: LG42lg50 UG power on and off

My brother dropped off his Radio Shack Auto Ranging "LCD Digital Multimeter" CAT no. 22-163. Will I be able to test the edge connectors with this? I would love to move forward on this today if I can.

[dick_barton]

Re: LG42lg50 UG power on and off

It looks as though it should do the job. Black lead (-V) on chassis, red lead (+V) to test voltages along edge connector. Set meter to 20V DV or higher as needed. Be careful as there are high voltages on the HOT side of the power supply which can be lethal.