LG42lg50 UG power on and off

[Stormyme]

Re: LG42lg50 UG power on and off

Ok I have tested the one connector that runs from the power supply to the main board. I have attached pics of my meter settings, the connector tested is circled in white and the results. That was scary good for sure lol I like this fix it yourself stuff lol

Awaiting your next instruction

I forgot to add that the tv was powered on when I did it.

[dick_barton]

Re: LG42lg50 UG power on and off

Perhaps Budm or ReeceyBurger123 can offer some advice here. I cannot find a manual on the power supply but taking note of the readings you have given everything appears normal for your power supply. The only reading I am unsure of is the ACD which I assume is AC Detect which is at 0V?? You appear to have all the other necessary voltages.

Has anyone got a schematic for the power supply they could share.
Thanks

[Stormyme]

Re: LG42lg50 UG power on and off

Is there another connector or something I can test next to narrow down the problem?

[dick_barton]

Re: LG42lg50 UG power on and off

Just to recap on the problem which was that the set was continuously restarting? Have I got that right?

[Stormyme]

Re: LG42lg50 UG power on and off

Yes correct. Flashing "no signal" as if it were trying to power up from stand by.

[dick_barton]

Re: LG42lg50 UG power on and off

If you press the menu button does the menu stay on the screen or does the set immediately restart.

I'm trying to work out from what you say whether the set does not see a signal and is leaving you watching a blank screen or if it is actually restarting.

Have you tried to input a signal into any other input. For example the AV input or from your computer to the RGB(PC) input or even a memory stick into the USB to see if any of those inputs are working.

[vinceroger69]

Re: LG42lg50 UG power on and off

in post 21 last picture it looks like you have only tested one side of the connector looking at the picture ive uploaded it looks like you need to test both sides of the connector and take voltages.
http://electro-medical.blogspot.co.u...lgp42-08h.html

[Stormyme]

Re: LG42lg50 UG power on and off

If you press the menu button does the menu stay on the screen or does the set immediately restart.

I'm trying to work out from what you say whether the set does not see a signal and is leaving you watching a blank screen or if it is actually restarting.

Have you tried to input a signal into any other input. For example the AV input or from your computer to the RGB(PC) input or even a memory stick into the USB to see if any of those inputs are working.

When I tried hitting menu or input button, if I was fast enough I would see the selection pop up on the screen before it went to no signal. A couple times it stayed on long enough to have me cycle through the choices. But none of the new choices fixed it. The end result was always the same. Flashing No signal. Holding down the power button on the tv is the only way I would get some extra time before it went to no signal.

Trying a pc or usb never occurred to me. But now that I have the back off I want to try everything I need to before putting it back together to try that.

[Stormyme]

Re: LG42lg50 UG power on and off

in post 21 last picture it looks like you have only tested one side of the connector looking at the picture ive uploaded it looks like you need to test both sides of the connector and take voltages.
http://electro-medical.blogspot.co.u...lgp42-08h.html

Should I remove the connector and test the pins directly?

[vinceroger69]

Re: LG42lg50 UG power on and off

with your black multi meter probe on metal tv chassis get the red probe and place down the side of each wire there a metal pin on the end of the wire so you should get a reading ok maybe do the left hand side of the connector first starting top to bottom then move to the right hand side take voltage readings of all pins (hope that makes sence)

[dick_barton]

Re: LG42lg50 UG power on and off

Stormyme - Can you also check you still have 24V on the other connector after the screen goes blanks.

Vinceroger69 - I'm wondering if it's a backlight fault.

[vinceroger69]

Re: LG42lg50 UG power on and off

maybe worth trying a dvd player etc and when screen goes off try shining a torch etc on the screen see if you still have a image
and yes dick barton does sound like it could be a back light fault and checking the 24 v plugs should give us some idea.

[Stormyme]

Re: LG42lg50 UG power on and off

with your black multi meter probe on metal tv chassis get the red probe and place down the side of each wire there a metal pin on the end of the wire so you should get a reading ok maybe do the left hand side of the connector first starting top to bottom then move to the right hand side take voltage readings of all pins (hope that makes sence)

The right side of that connector results

0
0
0
04.1
04.1
0
5.0
5.0
0
12.2
0
15.6

[Stormyme]

Re: LG42lg50 UG power on and off

Stormyme - Can you also check you still have 24V on the other connector after the screen goes blanks.

Vinceroger69 - I'm wondering if it's a backlight fault.

Results are

24.3

but when the back light flashes it reads 23.8

[vinceroger69]

Re: LG42lg50 UG power on and off

how long does the tv now stay on for? as in you can watch something or it it now powering on and off all the time.

[dick_barton]

Re: LG42lg50 UG power on and off

There are only 11 in your list but there are 12 pins on that side. Can you retest and send.

Can you take a picture of the P201 with the cable removed so I can see what the legends are written at the sides.

Looking carefully at the back of the set when you switch on, can you see the screen lights shine through some of the holes in the chassis, and does the light stay on.

Is the 04.1V = 4.1V or just a low reading 04.1mV??

[budm]

Re: LG42lg50 UG power on and off

"Yes correct. Flashing "no signal" as if it were trying to power up from stand by." That means the power supplies are on to provide the 24VDC for the inverter circuit to have backlights to see the "NO SIGNAL' on the screen and the main board is getting the Voltage to run to send the signal to the T-CON to show'NO SIGNAL' on the screen. It will go into standby after 5 seconds or 2 minutes (depend on the TV) due to lack of video signal.
If you look at the power supply connector on the bottom side of the board you will see more labels for the pin of that 24-pin connector.

[vinceroger69]

Re: LG42lg50 UG power on and off

"Yes correct. Flashing "no signal" as if it were trying to power up from stand by." That means the power supplies are on to provide the 24VDC for the inverter circuit to have backlights to see the "NO SIGNAL' on the screen and the main board is getting the Voltage to run. It will go into standby after 5 seconds or 2 minutes (depend on the TV) due to lack of video signal.
If you look at the power supply connector on the bottom side of the board you will see more labels for the pin of that 24-pin connector.

Cheers budm thats handy to know as not worked on one of these sets yet myself.

[Stormyme]

Re: LG42lg50 UG power on and off

There are only 11 in your list but there are 12 pins on that side. Can you retest and send.

Can you take a picture of the P201 with the cable removed so I can see what the legends are written at the sides.

Looking carefully at the back of the set when you switch on, can you see the screen lights shine through some of the holes in the chassis, and does the light stay on.

Is the 04.1V = 4.1V or just a low reading 04.1mV??

I corrected the results above to add the missing result.

What happens when I plug the power cord in........a blue light comes on on the T-con board, then I see the red stand by light come on. A white light flashes when the red light flashes. The tv is laying face down on my couch so I'm seeing all this from the back.

[Stormyme]

Re: LG42lg50 UG power on and off

I am having a hard time removing the connector. I hope these two images give you what you need.