LG uk6500 LEDs Turn on but no image.

[dskall]

Re: LG uk6500 LEDs Turn on but no image.

Still need pictures of the long boards attached to panel.

[Helikvar]

Re: LG uk6500 LEDs Turn on but no image.

ok, so is the processor still getting as hot with new mainboard?

Seems to be at about the same temperature.Maybe thats normal for these boards as they don't have much of a heatsink .It also doesn't get hot right away but takes 15 or 20 minutes.Also it has the same temp.with the lvds cables plugged in or left unplugged .

[Helikvar]

Re: LG uk6500 LEDs Turn on but no image.

Still need pictures of the long boards attached to panel.

Panel boards.

[dskall]

Re: LG uk6500 LEDs Turn on but no image.

not seeing any test points on any boards.

[nomoresonys]

Re: LG uk6500 LEDs Turn on but no image.

maybe test the little ceramic capacitors on those boards for shorts or very low ohms.

[Helikvar]

Re: LG uk6500 LEDs Turn on but no image.

maybe test the little ceramic capacitors on those boards for shorts or very low ohms.

C102 and C106 as marked by the red arrows both read shorted in diode mode both directions.I also included some better closeups of what look to be test points on these boards.

[nomoresonys]

Re: LG uk6500 LEDs Turn on but no image.

maybe check those two caps in ohm mode or see if one is hotter than the other, or just remove one and retest it and the one still on the board, it's likely that only one is shorted, when removed retest the pads where they connect also, to make sure the short is gone.

[dskall]

Re: LG uk6500 LEDs Turn on but no image.

Vcom ~ 5-7v, AVDD ~ 15v HVDD~ 7v. lockout is interesting.

[Helikvar]

Re: LG uk6500 LEDs Turn on but no image.

maybe check those two caps in ohm mode or see if one is hotter than the other, or just remove one and retest it and the one still on the board, it's likely that only one is shorted, when removed retest the pads where they connect also, to make sure the short is gone.

I removed C106 and measured the pads and both pads shorted both ways same as with capacitor so I assume cap is fine.(after desoldering it it fell to floor and yet to be located).C102 I havent removed yet and will soon .

[Helikvar]

Re: LG uk6500 LEDs Turn on but no image.

Vcom ~ 5-7v, AVDD ~ 15v HVDD~ 7v. lockout is interesting.

Tv powered on
VCOM 0.0 V
AVDD 0.0 V
HAVDD 0.0 V
DVDD1VBS 1.7 V
VTERM 1.2 V,1.0 V, 1.0 V, .9 V .(L1,L2,R1,R2 boards resp.)
LOCKOUT Voltages all 1.7 V

[nomoresonys]

Re: LG uk6500 LEDs Turn on but no image.

another cap that same size from a scrap board should be ok, can find some in old laptops, just have to be sure it's labeled on the board C for cap and not L for inductor, they look the same but are not.

[dskall]

Re: LG uk6500 LEDs Turn on but no image.

So your missing some voltages. Need to find where they are derived from. What ic.

[Diah]

Re: LG uk6500 LEDs Turn on but no image.

both TV no one wrote if he disconnect the U ribbon cable at time on each side of the panel buffer boards to have 3/4 screen ????? IC3000 on MB shutting down the panel when it come SOS signal ( pulling high Panel VCC 3.3V or cuting off it ) could be also if the glass of panel at some where at corner or VCC+ /- the GOLD layer under the screen brocken.

[nomoresonys]

Re: LG uk6500 LEDs Turn on but no image.

need to track down the short, not always easy tho.

[nomoresonys]

Re: LG uk6500 LEDs Turn on but no image.

maybe isolate, unplug ribbon cables from tcon to panel driver boards, check and see if you still have those shorts on the panel driver board/s.

[Helikvar]

Re: LG uk6500 LEDs Turn on but no image.

maybe isolate, unplug ribbon cables from tcon to panel driver boards, check and see if you still have those shorts on the panel driver board/s.

I have found that there is a half dozen caps reading short on the L1 and L2 panel boards.When I disconnect L2 from L1 all 3 L2 shorts on 3 caps disappear.Panel boards on right side R1,R2 don't show any caps shorting.L1 panel board shows 3 shorted caps so the problem appears to be in that area..
There is an 8 pin ic on L1 and also R1 that I believe are identical .Pin 6,8 are shorted on L1 panelboard however on R1 panel board pin 6,8 are not shorted.
Trying to find info on that 8 pin ic but no luck yet.It is marked ic101 on both L1 and R1.I will remove this ic to see if it is causing the shorts as well as the capacitors that read shorted until I find which one is causing the problem.

[Helikvar]

Re: LG uk6500 LEDs Turn on but no image.

Did you install your Main board?

Problem solved .Now have picture.Shorted ceramic cap on panel board L1 C102.

[Helikvar]

Re: LG uk6500 LEDs Turn on but no image.

maybe isolate, unplug ribbon cables from tcon to panel driver boards, check and see if you still have those shorts on the panel driver board/s.

Tv working now .C102 was shorted. I removed it and now have picture back.Many thanks for your assistance and guidance in cracking this one.Thanks to everyone else who also contributed to solving this problem.Every piece of advice certainly helps.

[dskall]

Re: LG uk6500 LEDs Turn on but no image.

Good work. Would be interesting to see what the function of ic101 is.

[nomoresonys]

Re: LG uk6500 LEDs Turn on but no image.

Glad to hear it, another fine save.