LG 42ln5300-UB won’t turn on and only has standby voltage

[NickIsFluffy]

Sorry for the multiple threads in different forums, I didn't quite know which forum to post this in, but I got some help, once again im really sorry about the multiple posts. But back to the title;

I have this LG 42ln5300-UB tv, but it won't turn on, there's only 3.3v standby but its supposed to have 3.5v on the power supply board. We already replaced the main board and the power supply board, but it didn't make a difference, I still only had that 3.3v standby. We are missing the remote for the tv, if that makes a difference. How can I fix this issue, I've already gone through all the trouble to buy a new part so i'm determined to fix the issue.

[nomoresonys]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

Post some good clear straight on pictures of each board and one of the whole back so we can see how they are connected, for pictures just hit go advanced and manage attachments, try test number 3 below, report voltages.

[NickIsFluffy]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

Post some good clear straight on pictures of each board and one of the whole back so we can see how they are connected, for pictures just hit go advanced and manage attachments, try test number 3 below, report voltages.

I already said that I replaced the Main board AND the Power Supply board, but was still getting only a standby voltage, the red light at the bottom doesnt show anything, when I plug the tv in, it just stands there, not light, no picture, no sound, no nothing.

[neilc6]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

With LN series, bad backlights are the most common failure. Does the tv turn on but with no backlight? 3.3V vs 3.5V is not an issue. If the tv responds to the on/off button and the backlights don't come on, they will be your main suspect.

[NickIsFluffy]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

With LN series, bad backlights are the most common failure. Does the tv turn on but with no backlight? 3.3V vs 3.5V is not an issue. If the tv responds to the on/off button and the backlights don't come on, they will be your main suspect.

Nothing happens, And on the power supply I should be seeing 12v and 24v, but nothing is shown exept for the almost 200v LED+ pin.

[NickIsFluffy]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

With LN series, bad backlights are the most common failure. Does the tv turn on but with no backlight? 3.3V vs 3.5V is not an issue. If the tv responds to the on/off button and the backlights don't come on, they will be your main suspect.

An I don't know how I can check that the TV responds to the On/Off button, if its the LEDs how do I know that the On/Off is responsive

[nomoresonys]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

Were the boards that you ALREADY REPLACED NEW??? NO??? that's why we do the tests, got it???

[nomoresonys]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

You won't get much help if you can't follow simple directions AND all you have to offer is ATTITUDE.

[NickIsFluffy]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

Were the boards that you ALREADY REPLACED NEW??? NO??? that's why we do the tests, got it???

Ok

[dick_barton]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

Can you post a picture of this box. If you have 200V at the led, then I suspect you probably have a led problem.

[R_J]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

The board outputs for a (42") 157.5v/ 341ma I agree he has an open led string.

how do I know that the On/Off is responsive

You use a meter to check the voltage on the PWR-ON pin when you push the power switch.

[NickIsFluffy]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

The board outputs for a (42") 157.5v/ 341ma I agree he has an open led string.
You use a meter to check the voltage on the PWR-ON pin when you push the power switch.

When I test it, it just shows 0.

[NickIsFluffy]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

Can you post a picture of this box. If you have 200V at the led, then I suspect you probably have a led problem.

Yeah I attached it

[handsworth]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

More than likely its the leds, however just a side note. When buying these tvs for repair, I have found out that the PO for some reason had turned the standby light off from the settings. Also in some cases the tv speaker was set to external or optical. Just something to consider.

[NickIsFluffy]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

More than likely its the leds, however just a side note. When buying these tvs for repair, I have found out that the PO for some reason had turned the standby light off from the settings. Also in some cases the tv speaker was set to external or optical. Just something to consider.

so whould I have to open the full metal back panel to check out the LEDs? also if its the LEDs, wouldnt the red light be at the bottom? because I dont see it.

[R_J]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

If you are getting 3.5v and also the 200v at the led's, this power supply is working.

[NickIsFluffy]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

If you are getting 3.5v and also the 200v at the led's, this power supply is working.

But im not getting the other 12v or 24v

[R_J]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

This is an always on power supply, the only reason you are not seeing +24 volts at the connector is because Q201 is not turned on. If you check the cathode of ZD201 you will find the +24v source (which will check higher)

[NickIsFluffy]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

This is an always on power supply, the only reason you are not seeing +24 volts at the connector is because Q201 is not turned on. If you check the cathode of ZD201 you will find the +24v source (which will check higher)

Sorry I dont know what the Q201 is and the cathode of ZD201, can u help me out?

[dick_barton]

Re: LG 42ln5300-UB won't turn on and only has standby voltage

You said in an earlier post that the led voltage was 200V. The photo you posted shows that a 42 inch set has a led voltage of 157.5V.
It looks as though you have an open circuit led(s) which is why the set appears not to be powering up. The over voltage protection is probably kicking in and powering down the power supply.