LG 47LV5500 - No picture, no back light, no sound, powers on.

[particlemann]

HI all - so I grabbed a non-working LG 47LV5500 from a friend as a project. I am totally new to TV repair...

So, here are the symptoms:

The TV has no picture and, as far as I can tell, no sound.

The unit powers on - i.e. when plugged in, the LED indicator shows red in standby and changes to white when powered on.

When powered on, the back lights do NOT come one and there is no picture visible with a flashlight. I plugged a laptop into HDMI 1 and 2, and while the laptop recognizes the TV properly, there is no sound. Of course I cannot verify what input the TV is set to, however, I pressed the "input" button on the front enough where it should scroll through either of the HDMI ports.

Based on reading through this forum and others, it seems like the problem might be with the main board. I have some basic multimeter skills, but where would I start testing? I did look around for a new main board, but they don't seem to easy to come by these days.

Thanks to all...

[CapLeaker]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

We need high resolution pictures of the PSU and main board. Check all DC voltages on P202 connector with TV on and post them with the corresponding pin out name. DRV-ON is your backlight signal.
You may want to recheck the sound with a DVD player and not the computer.

[particlemann]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

Here are the photos...

[budm]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

I am not sure if this power supply /LED driver board has built-in pull up resistors or, so try disconnecting the cables between the main board and the power supply board and then plug the TV into the outlet to see if you get backlights or not, also check the DCV between the two legs of the main filter caps (those 3 caps laying the side) in the primary side to see if you have close to 400VDC or not.

[Diah]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

Here are the photos...

your diagnose of main board correct, its mini LVDS, repair cant not, only replace or try chance of 30% to heat ( packing )your main board.

[particlemann]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

I am not sure if this power supply /LED driver board has built-in pull up resistors or, so try disconnecting the cables between the main board and the power supply board and then plug the TV into the outlet to see if you get backlights or not, also check the DCV between the two legs of the main filter caps (those 3 caps laying the side) in the primary side to see if you have close to 400VDC or not.

I disconnected the PSU from the main board. Once done, the power LED no longer turns red when TV is plugged in and on/off toggle seems to have no effect. Backlights did not come on.

I am not sure which are the main filter caps...

[particlemann]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

your diagnose of main board correct, its mini LVDS, repair cant not, only replace or try chance of 30% to heat ( packing )your main board.

By "heat packing" do you mean putting the board in the oven at 385F for 10 minutes?

[budm]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

I disconnected the PSU from the main board. Once done, the power LED no longer turns red when TV is plugged in and on/off toggle seems to have no effect. Backlights did not come on.

I am not sure which are the main filter caps...

No, you will not see power indicator because we are trying to do the power supply-LED driver board self test.
There are 3 black caps laying on their sides right next to each other and close to the AC inlet, so just use the meter to measure DC between the legs of each cap.
You must be careful since you are working in the primary deadly side of the circuits.

[ReeceyBurger123]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

By "heat packing" do you mean putting the board in the oven at 385F for 10 minutes?

DONT NOT DO THAT IT WILL DAMGED THE BOARD FURTHER ! Do what Bud says to diagnose it properly.

[martino]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

your diagnose of main board correct, its mini LVDS, repair cant not, only replace or try chance of 30% to heat ( packing )your main board.

At it again,dumbass? How do you even consider giving a "solution" by looking at a picture? How about a proper diagnoses first? GO AWAY.

OP,don't take advise from this dipstick,he's retarded.

[budm]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

http://www.shopjimmy.com/catalogsear...?q=LG+47LV5500

Is this the exact match of your board based on P/N from SJ?
http://www.shopjimmy.com/lg-eay62169...upply-unit.htm

LG EAY62169801 (EAX62865401/8) Power Supply 47LV5500 47LV5400 42LW5300
Ans also when you have all the cables connected you need to find out if you have >2.5VDC on PWR-ON pin and DRV-ON pin of the connector P201. We want to at least narrow down to see where the problem is first since main board is not cheap.

Pictures provided by shopjimmy.

[CapLeaker]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

Still need those voltages...

[particlemann]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

Sorry for going MIA after you all responded so quickly to me - it's just been one of those busy periods.

Anyway, yesterday, out of sheer reckless curiosity, I decided to throw the main board in the oven @385F for 10 minutes and let it cool for an hour. This is an absurd thing to do that has nothing to do with the thorough and methodical methods I came to this board to learn about. But, it worked... I put the main board back in and the TV works fine now - all inputs are working.

I have read enough about "reflowing" motherboards etc that I get why it worked, but it still just strikes me as just silly. And, while I am thrilled to have the TV working, I now need a new project where I will actually learn something!

Many thanks to all of you for responding to me so quickly and your willingness to help.

[thoma]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

http://alpengeist-tvrepair.blogspot....-clicking.html

[dick_barton]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

Out of curiosity I put an old board of mine into the oven to see what would happen to the circuit board, 380 deg F for 10 mins and I must admit it did not do the capacitors any good or the scart sockets.

The capacitors bulged and the plastic surround of the scart sockets melted.

I monitored the oven temp using a thermocouple but the oven was fan assisted if that makes any difference.

[ReeceyBurger123]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

Just use a hot air gun and do it, not the shiten/oven method. But glad to hear its fixed but for how long ?

[particlemann]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

Yes - how long indeed!

[Diah]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

when it work then will work, unless parts failed. happy you get it working.

but the oven was fan assisted if that makes any difference.

when you sitting at sauna you can feel its warm, but when the sauna master start to waved the towel ( like the fan ) all peoples who are sitting there feels their faces burning.

[ReeceyBurger123]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

when it work then will work, unless parts failed. happy you get it working.



when you sitting at sauna you can feel its warm, but when the sauna master start to waved the towel ( like the fan ) all peoples who are sitting there feels their faces burning.

Thats the worst comparison I have ever heard in my life.

[budm]

Re: LG 47LV5500 - No picture, no back light, no sound, powers on.

dick probably has convection oven which has fan to circulate hot air for even cooking and reducing the hot spot in the oven.