LG 65UQ80006LB

[bluemonkey]

This TV switches on with backlight and sound. Remote works also. I have replaced the combined Mainboard/TCON with no success. I have also looked at the thin boards connected to the LCD with a thermal camera to check for shorted caps etc, with nothing obvious. Could it be the power supply board? It is outputting the 13.2v required. Thanks

[EazyBone]

PSU if it's outputting correct voltages then no it's not it.

The main board/TCON is one board together?
It helps if we have some pictures of the back of tv and each board

[Davi.p]

lacks of the defect, i think no image, ok? Thermal camera used how? is there a short reading in ohms across caps? can you probe with oscilloscope various clock signals in the turn on moment?

[bluemonkey]

Hello, from what I understand the mainboard is also the TCON. I will upload some photos asap.

I used a FLIR thermal camera so not the best. I couldn't see any hotspots. Unfortunately I dont own an oscilloscope but have a good multimeter.

So if the resistance is low the cap is shorted? Can I use continuity mode across the cap to see a short?

Thanks

[nomoresonys]

Sure, put a probe on each end, if you get continuity it's either shorted or something nearby is.

[bluemonkey]

B101 and B104 are short but I'm not sure what they do

[bluemonkey]

[nomoresonys]

If you mean BD101 it should show continuity it's a jumper.

[Davi.p]

short circ. on a cap is zero ohm, Flir is the famest and probably the best thermal cam brand here... who has bread has no teeth, who has teeth has no bread.. it is not enough to turn on the camera and watch... only if a short is measured, it is injected some volts, also 12v, with increasing current from zero..but there is a cheaper / easier way..

[nomoresonys]

This isn't a quiz show, if you have some SOUND advise just give it, nobody has time for BS.

[bluemonkey]

Will purchase a bench power supply to inject voltage tomorrow.

Does anyone have a schematic?

[Davi.p]

Nooo! If you are not a tinkerer, why not to use the simplest way? AS I SAID if you don't probe a short with multimeter is absolutely waste time / money injecting..

[bluemonkey]

Ok. I've checked all the caps with continuity mode and they all seem fine. There are a few groups of resistors in rows, some reading 0 ohms. I'm not sure what their values are supposed to be tho. Are they supposed to be the same if they are in rows?

[Davi.p]

If there are no diodes to check then you can try the same old method of inserting little tape masks on one of the output ribbons to disable some clock circuits.. youtube is full of these not full restoring

[Diah]

you have sound and BL but screen black , you replaced the MB and the result remain same..

1- check the LVDS between MB and panel if the position 1 & 2 correct on the panel soide
2- you have U ribbon on each panel buffer boards try disconnect one a time to see if screen will come 3/4 displaing

never .. never use external source to power current to the panel this is big mistake SHOULD WHO TALKING ABOUT IT FORGET IT FOREVER:

[bluemonkey]

I've had a bit of luck with the tape method but cant get it perfect.

Will try the U ribbons

[bluemonkey]

Is it not safe to inject say 0.5v and see what gets hot with the thermal cam?

[Diah]

Is it not safe to inject say 0.5v and see what gets hot with the thermal cam?

wrong.. panel currents not only v. its depend on frequency Hz

[Davi.p]

That defect is not suitable for normal injection, short killing method exists, i never f

tried it but i feel it is not safe enough, i think best method is one other..

[bluemonkey]

Ok so its been about a month since I last tried the TV. I plugged it in today and it worked fine. After putting it back together and plugging it in, it is the same problem again. What can cause this? Capacitor?