LG42lg50 UG power on and off

[dick_barton]

Re: LG42lg50 UG power on and off

Plug connector P201 back in and carry out the same test measuring the voltage on the ACD pin. This time it's me who waits in anticipation.

[Stormyme]

Re: LG42lg50 UG power on and off

Plug connector P201 back in and carry out the same test measuring the voltage on the ACD pin. This time it's me who waits in anticipation.

When I plugged p201 back in and powered up the tv, the tv actually stayed on for a minute. Then it went back to flashing. The reading is a steady 4.1 now.

[dick_barton]

Re: LG42lg50 UG power on and off

Those results give the power supply a clean bill of health. It's late here so I'm closing down for the night.

Can you check the following using your meter as earlier on with all connectors back in place:-
P201 Pin17 (ERROR PIN)
P201 Pin 20 (Inverter On/Off)
P204 Pin 12 (Backlight On/Off)
and see what voltage is on those pins when switched on and when it flashes

Please take a little time to look through the manual attached which may give you some idea of what to do next.

Perhaps carry out the test on page 31. Remove P201. Add the 10K resistor across the pins shown and connect a small wire across 19 & 20 as shown.

[Stormyme]

Re: LG42lg50 UG power on and off

Those results give the power supply a clean bill of health. It's late here so I'm closing down for the night.

Can you check the following using your meter as earlier on with all connectors back in place:-
P201 Pin17 (ERROR PIN)
P201 Pin 20 (Inverter On/Off)
P204 Pin 12 (Backlight On/Off)
and see what voltage is on those pins when switched on and when it flashes

Please take a little time to look through the manual attached which may give you some idea of what to do next.

Perhaps carry out the test on page 31. Remove P201. Add the 10K resistor across the pins shown and connect a small wire across 19 & 20 as shown.

P201 Pin 17 reads 0
P201 Pin 20 reads 4.4 only when the back light flashes on. Reads 0 in standby

I dont see P204

[dick_barton]

Re: LG42lg50 UG power on and off

Can you check if this is P204?

[Stormyme]

Re: LG42lg50 UG power on and off

P204 Pin 12 reads 3.2 only when the back light flashes on. Reads 0 in standby.


Is this turning out to be a main board replacement? If so will I be able to hook the PS3 back up using HDMI? I ask because I do not know if it was coincidence or cause that all this happened a couple months after hooking up the PS3 using HDMI. From what I was seeing all over the web in the beginning it looked like LG is known for this issue being tied to HDMI or PS3. Have you guys had a lot of LG's coming in with this issue?

[dick_barton]

Re: LG42lg50 UG power on and off

Hi,
Thanks for the readings. Backlights are switching off which was expected.
Hang in a just a little bit longer, nearly there.

This is the last test which checks if the backlight circuitry is faulty.

Follow the instructions on page 31 of the above manual
Lift out the connector P201 and connect the resistor between Pin11 to Pin 19 and a wire between Pin 19 & Pin 20 as shown. Check the voltage on pin14 of P204 (Backlight Error) as you power up and see what happens.

Pin 14 should stay at 0V and if it does not then it's a fault in the backlight circuits.
If it stays at 0V then it would appear to be your main board.

[Stormyme]

Re: LG42lg50 UG power on and off

I am going to Fry's Electronics store around the corner. I am picking up some 10K ohm resistors and hard drive jumpers. Anything else I might need? Anything you need? LOL

[dick_barton]

Re: LG42lg50 UG power on and off

That's all you need to complete the final task.
Good luck

[Stormyme]

Re: LG42lg50 UG power on and off

Hi,
Thanks for the readings. Backlights are switching off which was expected.
Hang in a just a little bit longer, nearly there.

This is the last test which checks if the backlight circuitry is faulty.

Follow the instructions on page 31 of the above manual
Lift out the connector P201 and connect the resistor between Pin11 to Pin 19 and a wire between Pin 19 & Pin 20 as shown. Check the voltage on pin14 of P204 (Backlight Error) as you power up and see what happens.

Pin 14 should stay at 0V and if it does not then it's a fault in the backlight circuits.
If it stays at 0V then it would appear to be your main board.

The final result is 0. Wow that was tricky lol

awaiting next instruction

[budm]

Re: LG42lg50 UG power on and off

I still say you have main board problem.
Does it ever show the Video images on the screen beside the 'NO SIGNAL'?

[Stormyme]

Re: LG42lg50 UG power on and off

I still say you have main board problem.
Does it ever show the Video images on the screen beside the 'NO SIGNAL'?

Based on the last result of 0 it looks like dick_barton agrees with you.

The few times I was able to hold the power button on the tv on and have it work for a while, the video was great. The times I tried to hit the input on the remote, I was able to see the selection, then back to no signal.

[dick_barton]

Re: LG42lg50 UG power on and off

If Pin 14 of P204 stayed at 0V then that says no backlight fault so I must agree with Budm and say it's a main board fault.

Thanks to Budm & Vincerogers69 for their support while carrying out the various tests.

[Stormyme]

Re: LG42lg50 UG power on and off

If Pin 14 of P204 stayed at 0V then that says no backlight fault so I must agree with Budm and say it's a main board fault.

Thanks to BudM & Vincerogers69 for their support while carrying out the various tests.

Thank you to all of you. Very awesome guys, fantastic help.

I was looking for a replacement board and shop jimmy is out of stock and I am not sure about the choices on Ebay. I was going to post a request in your looking for thread. Any other places? If one of you had it, I would rather give the money to you and badcaps.

Also is there any way to find out if the PS3/HDMI caused it? I do not want to hook up the console again if there is an issue.

[dick_barton]

Re: LG42lg50 UG power on and off

I cannot offer an opinion regarding the HDMI problem as I have no idea.

If you pay with Paypal you have an extra level of protection in the event that buying a dud on Ebay, you can get your money back.

This one looks good for the price, however you do have to match your board number carefully.

Your circuit board details will be something like this:-
42LG50-UG
LA84D
EAX52164402(8)
08.08.08 H J M

http://www.ebay.com/itm/LG-42-42LG50...-/361247867421

Good luck

[Stormyme]

Re: LG42lg50 UG power on and off

Mine is

42LG50-UG
LA84D
EAX52164402(6)
08.07.07 H J M

The one on EBay also guarantees replacement if it doesnt work. Very cool Thank you

[dick_barton]

Re: LG42lg50 UG power on and off

The numbers are slightly different so I don't know if this is a direct replacement. Look carefully at your board and compare it with the one shown in minute detail.

[lcdrepair]

Re: LG42lg50 UG power on and off

I had the problem with tv powering on and off and the cause was a failed power button. It was stuck with contacts closed. I unplugged the small board with the ir sensor and power button from the mainboard just as the backlight came on... and the tv stayed on. I removed the failed button from the board. Plugged the board back in and turned on the tv with remote. Worked fine stayed on.. i replaced the push button and got it working 100%.

[lcdrepair]

Re: LG42lg50 UG power on and off

I had the problem with tv powering on and off and the cause was a failed power button. It was stuck with contacts closed. I unplugged the small board with the ir sensor and power button from the mainboard just as the backlight came on... and the tv stayed on. I removed the failed button from the board. Plugged the board back in and turned on the tv with remote. Worked fine stayed on.. i replaced the push button and got it working 100%.