I have removed all the wires from the power supply except the main control. It turns ON and OFF and I have checked a pin 24v, it goes down to 15V, then 24 again.
Tahnaks in advnace
I ran into this with my 32" LG 32LD550 television yesterday.
tl;dnr version - set your output device (Blu-ray, cable box, satellite dish receiver, set tup box, etc) to 720p and see if you TV stays on any longer.
Here is some observation:
This started happening to me yesterday when I was watching movies from my Plex server via a Roku (version 3, if we are counting) hooked up to HDMI1. I moved to HDMI3, same thing.
I unplugged the Roku, plugged in my Chromecast to HDMI1, same issue. Then I remembered that I had set the Roku to 1080p instead of 720p just before I shut it off the last time. I reset the Roku to 720p, and bingo! no power off.
I have not tested any app on the Roku other than Plex. I was streaming 1080p from to the Chromecast, same movie, also using Plex, so I need to figure out if I can decrease the output to 720p as a test for that. I plan to try Netflix and Hulu on the Roku, and perhaps 1080p/720p on Youtube with the Chromecast.
HDMI2 is plugged into my DirecTV receiver - which is set to output 1080p as the maximum resolution. That said, watching DirecTV has NEVER caused my TV to shut off, but it must be said that the highest resolution for MOST channels is 1080i. Perhaps that is not enough to overload it. I'm not really willing to pay for a 1080p stream from DirecTV just to do a test, but if all other 1080p options result in the TV shutting off, I may have to just to satisfy my curiosity.
I have not done anything with HDMI4 recently, my final HDMI input. I have it hooked up to a small Android based gaming system, and have not ever had an issue with it.
Had same problem with an LG 32ls575t set which developed the problem after 13 months, just oiutside the warranty period.
Set would reboot every couple of minutes with a firmware version message and "please wait".
Rang the supplier, Currys, and an engineer advised to press and hold the ON button for 30 seconds and then release it.
Set was fine after that. Very surprised when he told us the problem is caused by static build up on the set and by holding the button down it cures the problem. Still find it hard to believe. Suspect it did some factory type reset to the set. Anyway it fixed the problem so far !!
Just hope to help anybody has the same problem. I had the exact same problem after 2 years of purchasing my LG 47LK520. Tried everything from factory reset to update firmware. Didn't work.
Finally, I bought a power supply board from eBay and replaced it myself. It took about 20 minutes. But the problem persists UNTIL I did ANOTHER factory reset. So, a new power supply board + a factory reset fixed it.