Lg 50pk950 turns on by itself (stumped!)

[Truncatedhose]

Re: Lg 50pk950 turns on by itself (stumped!)

Logically however unlikely it leaves cable from main to sub suspect. Did you try unplugging cable at sub not main? Is there anything else on that connector like wifi?

I see how logically, it seems like an answer. Yes, I've unplugged it at either end, if that's what you're asking? There's no wifi on that cable.

[Truncatedhose]

Re: Lg 50pk950 turns on by itself (stumped!)

on the main board, connector p703, what are the dc measurements on
pin1
pin3
pin4

everything hooked up and in stby.

measure for several minutes and let us know if they fluctuate at all and if so, how much.

Here are the results:

pin1: 2.858v
pin3: 3.159v
pin4: 3.304v

No fluctuation found within several minutes, but I'm not standing there for 20 minutes or whenever the TV turns itself on by itself to see what happens. I suppose I could rig up something and leave it there using min/max?

[dskall]

Re: Lg 50pk950 turns on by itself (stumped!)

Key1 or key2 pin carry signal to turn on. I would find which key and monitor it in min/max to see if the turn on signal is coming from key/sub circuit

[Truncatedhose]

Re: Lg 50pk950 turns on by itself (stumped!)

I think the problem has been found. After doing all the monitoring of the key1 pin on the SUB board and finding that the voltage would randomly dip I checked the 3.3v stby pin on the SUB board, which was also dipping randomly. Then I checked the 3.3v stby at the power supply itself and found it is dipping there, too, and logically would be the source of the aberrant voltage issue, which in turn is causing the SUB board to think it should turn the TV on. So, the answer: bad power supply board. I'm going to see if the board has bad caps or a problem with it's controller IC, since these boards are scarce and/or a little spendy.

[dick_barton]

Re: Lg 50pk950 turns on by itself (stumped!)

Hope you've nailed it.

[Truncatedhose]

Re: Lg 50pk950 turns on by itself (stumped!)

In case this helps anyone else, this case was solved! Ended up being C305 on the power supply board (22ufd@450v) electrolytic capacitor causing the 3.3v stby to be unstable and intermittently trigger self-turn on when it dipped too much and returned to normal. Replaced it and all is well!

[dskall]

Re: Lg 50pk950 turns on by itself (stumped!)

Glad it's fixed. Thanks for feedback