Lg32lb561v power supply(i think?) problem

[gtanick]

Hey guys! I've been trying to fix this tv i had laying around for some time, was wondering if you could help me find the problem because i ran out of knowledge, i'm just a self taught repair wannabe so i apologise in advance for my lack of knowledge

So, one day this tv stopped turning on, only flashed the red light once and then stopping, i took it apart and looked at the power supply, noticed two blown capacitors (the red circled ones) and replaced them, soldering was a bit wonky because one was longer but its the right farad and voltage, still nothing, no turning on no pic.

Then i replaced every capacitor i could get my hands on, nothing.

I tested fuses and diodes (well i think i did, i'm not so sure of my work ) they seemed all fine.

Searched the schematics of the board EAX65391401 3.0 and started trying to understand something.

I measured the voltages at the connector that goes in the logic board, 3,5v 24v and 12v are there and perfectly fine

Then i measured the backlight current that should be 117v and found that it was putting out approx 140v

Oh and today i noticed a really low crackling noise (bzzzzzzzz) coming from the bottom right of the board, like an electric dispersion but could not find where it was

Tl;dr Tv didn't turn on, only one red blink, Replaced bad caps on powersupply, still nothing, backlight line puts out 140v instead of 117v, crackling noise on bottom right of the board, i have no idea of what i'm doing

Sorry for the long post, i tried to put as many info as possible, tried to follow the guides sticked at the top but nothing,

Am i better off buying a new board or is there hope?

Thanks a lot

[R_J]

Re: Lg32lb561v power supply(i think?) problem

What made you think those caps were blown? they usually don't give a problem, Usually a high led voltage indicates an open led string in the panel.

[gtanick]

Re: Lg32lb561v power supply(i think?) problem

What made you think those caps were blown? they usually don't give a problem, Usually a high led voltage indicates an open led string in the panel.

Hi, thanks for the answer!

I still keep those capacitors because i never saw something like that, i attached a pic of those

So is it the led stripes in the panel's fault? i tried measuring while unplugging the connector and it still gives out 140v like if the 117v line broke somewhere on the power supply

If i may ask you a question, would the tv turn on without backlight if i unplugged only that and everything else was fine?

Thanks again!

Edit: i attached another pic to show where i got the 140v (117v) measurement, is that the right spot?

Edit2:Now measuring from the + and - on the connector gives out 63-64v while putting - on the big screw in the bottom left corner of the board still gives 140v, this tv confuses me lol

[R_J]

Re: Lg32lb561v power supply(i think?) problem

Those caps are definitely bad. How many wires go to the leds? If it is just two and you measure 64v I would think the backlights should be on
If you measure the voltage from the led (-) to ground what do you get? they usually supply full voltage to the (+) side and control the (-) side of the led's.
I still think its bad led string.

[gtanick]

Re: Lg32lb561v power supply(i think?) problem

Those caps are definitely bad. How many wires go to the leds? If it is just two and you measure 64v I would think the backlights should be on
If you measure the voltage from the led (-) to ground what do you get? they usually supply full voltage to the (+) side and control the (-) side of the led's.
I still think its bad led string.

Its 2 wires to the leds, measuring those 2 wires gives out 80v when leds are connected and 64v when they are not

Led(-) to ground gives 0.00 and led(+) to ground still gives 140v

Thanks again for your time

[R_J]

Re: Lg32lb561v power supply(i think?) problem

I would still suspect bad led string, Here is a video that might be of some help https://www.youtube.com/watch?v=peG1cIpXqeg

[gtanick]

Re: Lg32lb561v power supply(i think?) problem

I would still suspect bad led string, Here is a video that might be of some help https://www.youtube.com/watch?v=peG1cIpXqeg

I will check the led strings, thanks again

[budm]

Re: Lg32lb561v power supply(i think?) problem

It has open circuit in the LED string some where, that is why the LED - Cathode return shows 0V.

[Andrew F. Ali]

Re: Lg32lb561v power supply(i think?) problem

Originally posted by budm: It has open circuit in the LED string some where, that is why the LED - Cathode return shows 0V.
+1k

[gtanick]

Re: Lg32lb561v power supply(i think?) problem

It has open circuit in the LED string some where, that is why the LED - Cathode return shows 0V.

I'll check it as soon as i come home

So if one of the leds is bad or there is an opening in the circuit of the leds the whole tv wont turn on at all right?

So i can be sure about the power supply right? If the leds are the problem, changing them would bring the tv back ?

i'm sorry i'm spitting out questions like a machine i'm just interested in how these circuits work

[budm]

Re: Lg32lb561v power supply(i think?) problem

Is your LCD panel sticker: NC320DXN-VSBP1? You need to match the strips to the LCD panel.
The LED strips look something like this: https://www.ebay.com/i/283120816368?chn=ps
The LED's are connected in series so if one go open circuit then you will not get any lights.

[gtanick]

Re: Lg32lb561v power supply(i think?) problem

Is your LCD panel sticker: NC320DXN-VSBP1? You need to match the strips to the LCD panel.
The LED strips look something like this: https://www.ebay.com/i/283120816368?chn=ps
The LED's are connected in series so if one go open circuit then you will not get any lights.

Thanks for the answer again

I think i expressed myself wrong english is not my first language, sorry , i meant if there's an opening in the leds circuit, should i get sound/tv working and no lights or no sign of life at all? Because looking at some videos regarding this problem they all seem to have sound and tvs working without backlight ofc but mine isnt putting out any sound nor it does turn on
When i plug it the red light blinks and dims to off, pressing the button does not do anything

[gtanick]

Re: Lg32lb561v power supply(i think?) problem

Quick update, YOU GUYS ARE AWESOME!!!
It was the led stripes, i found a couple of broken ones, just tried to bridge them to check if it would work and it did !!!
Thanks a lot guys, you understood in a blink of an eye what it was, i hope i can get to that level one day
Thanks again !!!

[Andrew F. Ali]

Re: Lg32lb561v power supply(i think?) problem

So are you going to purchase new strips and change them out? I would recommend changing all the strips as you don't want to go back in there as there is the chance of breaking the glass screen and destroying your TV.

[gtanick]

Re: Lg32lb561v power supply(i think?) problem

So are you going to purchase new strips and change them out? I would recommend changing all the strips as you don't want to go back in there as there is the chance of breaking the glass screen and destroying your TV.

Yeah, i already ordered them, i just tested without fixing everything back in place, when they'll arrive i'll swap them Thanks again !

[Andrew F. Ali]

Re: Lg32lb561v power supply(i think?) problem

Don't forget to give us a feedback.

[gtanick]

Re: Lg32lb561v power supply(i think?) problem

Don't forget to give us a feedback.

New stripes arrived, the tv looks as good as new! Cheers to you guys, thanks again for the massive help

[Andrew F. Ali]

Re: Lg32lb561v power supply(i think?) problem

Applause...You did well...thanks for the feedback.

[budm]

Re: Lg32lb561v power supply(i think?) problem

Make sure to turn down the backlights level to as low as you can to extend the life of the LED's.

[gtanick]

Re: Lg32lb561v power supply(i think?) problem

Applause...You did well...thanks for the feedback.

Thanks to you guys again

Make sure to turn down the backlights level to as low as you can to extend the life of the LED's.

Will definitely do, thank you !