Lg49uh620v

[shandybass]

This tv belongs to a friend who was gifting it to an elderly lady. She complained that it wasn't bright enough for her deteriorating eyesight.
Sure enough it was dimmish with the backlight, contrast and brightness all set to maximum.

Choosing vivid mode helped slightly but obviously there is a problem. I'm an old engineer more used to crt screens than led. Retired now but would like a play with this set.
I'm struggling to decide whether the fault lies with the backlights or the power supply.

I have no schematic for the board which is a EAX66923201 1.4 but the voltage with backlights connected is around 162v and 175v disconnected. I expected it to be higher. Can anyone advise?

[nomoresonys]

Re: Lg49uh620v

couple things to try, firmware update, turn off any energy saving settings.

[shandybass]

Re: Lg49uh620v

They were the 1st things I tried mate. There is definitely a fault on this set. I am just trying to ascertain whether the fault lies with the power board or if there may be a faulty led or 2.

I don't relish removing the panel needlessly.

[neilc6]

Re: Lg49uh620v

Backlight issues are 99% the backlights themselves and rarely the power supply in LGs. LEDs will wear and burn out just like light bulbs. On UH series, error can cause the TV to shut down.

[shandybass]

Re: Lg49uh620v

Backlight issues are 99% the backlights themselves and rarely the power supply in LGs. LEDs will wear and burn out just like light bulbs. On UH series, error can cause the TV to shut down.

Got a feeling this is one of the rare cases then. I watched a video of a guy diagnosing then changing the backlights on an LG 40LF320v. He measured between A and B and read 250v dc which he stated was a good supply voltage for the backlights.
If I measure this bigger set between those 2 points I read a PD of only 98v. If I measure A, the midpoint and B with respect to chassis I get 64v, 113v and 165v respectively.

I'm just hoping that someone can confirm that these voltages are indeed too low before I order a replacement.

[lotas]

Re: Lg49uh620v

Typically, the power supply board consumes output voltage and backlight current.

[shandybass]

Re: Lg49uh620v

Typically, the power supply board consumes output voltage and backlight current.

Thank you lotas. I completely missed that info on the board. I have just checked the board from the video I watched and it is marked 264v so seemingly this board may be supplying a near enough correct supply voltage.

Seems there is very little choice other than to remove the panel and take a look at the backlights.
Thanks again.

[Diah]

Re: Lg49uh620v

can we see how it look the picture.. !!! one photo better than 1000 words

[sintv]

Re: Lg49uh620v

.Change leds. 100% faulty. Youll have a whole strip out but unless you dismantle and check them you wont know

[Davi.p]

Re: Lg49uh620v

Can you post the PS board model? 165v respect to gnd and only 98v A>B is not good, i think something is wrong with the led driver ic or the current sensing resistors...

PS: does any one knows a good program on Android to edit pictures in landscape screen?

[nomoresonys]

Re: Lg49uh620v

Can you post the PS board model? 165v respect to gnd and only 98v A>B is not good, i think something is wrong with the led driver ic or the current sensing resistors...

PS: does any one knows a good program on Android to edit pictures in landscape screen?

If you have a question start a thread, remember we don't want to make things CONFUSING.

[Diah]

Re: Lg49uh620v

If you have a question start a thread, remember we don't want to make things CONFUSING.

LOL...
the words Hijack i just learned it here and from one user who mentioned by nomoresony... search this forum with google under words " Hijack"

you will find the first match same person.. so Mr. Hijack can you please stop this and back to normal at 2023.... please....

[nomoresonys]

Re: Lg49uh620v

Well I was just stunned when this guy tried to derail the thread with a question about this android crap.

[shandybass]

Re: Lg49uh620v

.Change leds. 100% faulty. Youll have a whole strip out but unless you dismantle and check them you wont know

My backlights arrived from China yesterday so will be fitting them tomorrow. Is definitely the backlights, they are blue.

Cowdenbeath eh? I was born in Lo'gelly