Lg 50pk950 turns on by itself (stumped!)

[dick_barton]

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

I would think it would be best if you could 'scope it because of the switch mode supply frequency, but using the meter on AC would be a start. If this was the problem then I suspect it would be the lower voltages that supply the mainboard that could have an issue.

[Truncatedhose]

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

Your on/off key presses should change voltages on one of the wires. Is there any missing shielding or grounding. Still wonder if mainboard doesn't factor in to this somehow

I was going to try putting the SUB board into a shielded bag and ground it to see if it stops turning on. I'll let you know.

[Truncatedhose]

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

I would think it would be best if you could 'scope it because of the switch mode supply frequency, but using the meter on AC would be a start. If this was the problem then I suspect it would be the lower voltages that supply the mainboard that could have an issue.

I will check and see what I can find and let you know.

[dskall]

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

Key1 or key2 should change voltage when you press power. Monitor which ever changes voltage

[attainteddragon]

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

just to confirm,
tv turns on by itself when all hooked up,
when you swapped out the sub board and all hooked up,
when you cover up the ir sensor,

but does not turn on when the touch pad is hooked up.

if that is right, it has to be the touch pad, or a component that the on signal travels through on the sub board that comes from the touch pad.

i would pull the touch pad and look it over.

[dskall]

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

That was my first assumption. He says it only works with sub board unplugged. As in post 8. Strange one

[attainteddragon]

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

it is rather weird, and if the signal passed through something on the sub board that was breaking down, then it would of been solved with the change out of the sub board. i think that the main was changed out too from memory, so that leaves the touch pad and less likely, the harness from the touch pad to the sub board.

i am not overly familiar with how the touch pads work. since mechanical buttons can suffer from tin whiskers, i'm wondering id touch buttons can too. (just thinking out loud now).

[dskall]

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

I haven't encountered touch pads. I believe they work on capacitive effect. What seemed strange to me but may not be. Post 30 says just handling sub with touch pad disconnected will cause it to turn on if I understood correctly.

[attainteddragon]

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

baffling.

i would still remove the ir sensor. that way, you could eliminate the remote system and then you are strictly down to the keypad area.

[Truncatedhose]

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

just to confirm,
tv turns on by itself when all hooked up,
when you swapped out the sub board and all hooked up,
when you cover up the ir sensor,

but does not turn on when the touch pad is hooked up.

if that is right, it has to be the touch pad, or a component that the on signal travels through on the sub board that comes from the touch pad.

i would pull the touch pad and look it over.

No, it DOES turn itself on with the touch pad connected, but it ALSO turns itself on with the touchpad disconnected. So the touch pad can't be the cause, right? The only way to stop it from turning itself on is to unplug the SUB board from the main board. The SUB board is the little board that the touch pad connects to, then the SUB board connects to the main board. Ever since I discovered that unplugging the touch pad doesn't stop it from turning itself on, I have left it unplugged and all my tests have been with it unplugged.

[Truncatedhose]

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

Anyone have a schematic of for this TV or for this SUB board? I found a SM on Elektrotanya, but it's hard to find a schematic in it showing the SUB board. There's something called the SUB Board I/F, but it looks different.

[Truncatedhose]

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

Found the training manual which has some interesting info on the SUB board and keypad.

[dskall]

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

Sub board is pretty simple. ic100 should be touch pad controller. May get data sheet if you look up number.

[dskall]

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

I'm getting 404 not found

[Truncatedhose]

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

I'm getting 404 not found

I just uploaded it instead (see my previous post).

[attainteddragon]

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.

[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.

I will test on Monday and get back to you, thanks!

[attainteddragon]

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

there is a lot of other things that you can test if you read through that manual.

p1001 connects to what is called motion sensor, (not sure how it is routed) but that can influence the control signals too.

i have a px series here at the moment, which is almost identical. i can compare some resistance readings if necessary, but they are all listed in the manual.

we will get to the bottom of this, even if i never sleep again. :P

[Truncatedhose]

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

there is a lot of other things that you can test if you read through that manual.

p1001 connects to what is called motion sensor, (not sure how it is routed) but that can influence the control signals too.

i have a px series here at the moment, which is almost identical. i can compare some resistance readings if necessary, but they are all listed in the manual.

we will get to the bottom of this, even if i never sleep again. :P

Your kindness and dedication are very much appreciated! I am going to monitor those pins you spoke of last week and get back to you later.

[dskall]

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?