LG 60PB6600-UA No picture, whine from PSU

[KuroYamaneko]

Hello all,

I was recently given an LG 60PB6600-UA that was having issues.
I was told that it had audio, but no picture. When I have attempted to turn it on, the screen will flash grey "snow" then go black. While the tv is turned on, I can hear a whine coming from the power supply area.
The standby red light is on while plugged in, but turns off when tv is turned on.

I have tried disconnecting ysus and zsus, only stops the grey flash from happening, still black screen.
I can't see any obvious bad capacitors.

I'm hoping you can help me with this,
Thanks!

[tvtimmy]

Re: LG 60PB6600-UA No picture, whine from PSU

On your last pic, there is the big main cpu. Just up from the right corner are two holes marked auto gen. Unplug the cable that goes from the mainboard to the one in the pic(logic board).put a piece of wire in each hole and plug in the tv. If you see screens of colors and patterns the mainboard is bad.

[KuroYamaneko]

Re: LG 60PB6600-UA No picture, whine from PSU

Just gave that a shot, the grey seemed to be a bit brighter, and lasted slightly longer, but no patterns.

[petehall347]

Re: LG 60PB6600-UA No picture, whine from PSU

how much current is it pulling from the wall ?

[dick_barton]

Re: LG 60PB6600-UA No picture, whine from PSU

What voltages do you have at the connectors in the red boxes when you switch on?
eg.

P811
Pin 1 VS =
Pin 2 VS =
Pin 3 No Connection
Pin 4
etc


P813
Pin 1 1(7V) =
Pin 2 (17V) =
Pin 3 (GND) =
Pin 4 (GND) =
etc

[KuroYamaneko]

Re: LG 60PB6600-UA No picture, whine from PSU

Readings are from top pin down

p811
Pin 1 VS = 205
Pin 2 VS = 205
Pin 3 No Connection
Pin 4 VA = 54.94
pin 5 M5v = 5.1

P813
Pin 1 = 3.3
Pin 2 = 3.2
Pin 3 = 5.1
Pin 4 = 0
Pin 5 = 0
Pin 6 = 5.1
Pin 7 = 5.1
Pin 8 = 0
Pin 9 = 16.9

[dick_barton]

Re: LG 60PB6600-UA No picture, whine from PSU

Hi KuroYamaneko, It looks as though there may be 18 pins on the second connector. One row being 1 to 17 (all the odd pins) and the second row being 2 to 18, all the even pins. It's really useful if you put the name associated with the pin number alongside with the voltage read.
Could you also post a picture of the white sticker stuck on the panel which gives the voltages on it. Thanks

Take a look at the following Youtube video
https://www.youtube.com/watch?v=oMi76UoIkbo

[KuroYamaneko]

Re: LG 60PB6600-UA No picture, whine from PSU

Sorry about that,

p811
Pin 1 VS = 205
Pin 2 VS = 205
Pin 3 No Connection
Pin 4 VA = 54.94
pin 5 M5v = 5.1

P813
Pin 1 M_ON = 3.3
Pin 2 Auto_GND = 0
Pin 3 RL_ON = 3.2
Pin 4 AC_ON = 5
Pin 5 5.2V = 5.1
Pin 6 17V_DET = 2.2
Pin 7 GND = 0
Pin 8 VS_ON = 3.0
Pin 9 GND = 0
Pin 10 GND = 0
Pin 11 5.2V = 5.1
Pin 12 VS_DET = 2.8
Pin 13 5.2V = 5.1
Pin 14 5.2V = 5.1
Pin 15 GND = 0
Pin 16 GND = 0
Pin 17 17V = 16.9
Pin 18 17V = 16.9

[dick_barton]

Re: LG 60PB6600-UA No picture, whine from PSU

Your voltages all look good. There is an led on the logic board (photo 6 of 6). Is it flashing and at what on/off rate. eg 1 sec on, 1 sec off.
Also can you check if you have sound.

[KuroYamaneko]

Re: LG 60PB6600-UA No picture, whine from PSU

The led blinks 4 times over 1 second when tv is turned on, then 1 sec on, short off, short blink, 1 sec on, short off, short blink, 4 sec off

not sure how to verify sound, but I was told the sound worked

[dick_barton]

Re: LG 60PB6600-UA No picture, whine from PSU

I think the blink sequence of the Logic board led should be on 0.5 sec, off 0.5 sec.

Do you have the correct voltages on P130?

There's a Vy voltage on the Ysus board which is often read between two "identified points" but I cannot see where they are located on your Ysus photo of the board. The two test points may be above R254 and you measure the voltage between the two points and not chassis.

Hopefully others can help you from here since it's starting to go beyond my current knowledge.

[KuroYamaneko]

Re: LG 60PB6600-UA No picture, whine from PSU

Readings for P130

Pin 6 VS = 205
Pin 5 VS = 205
Pin 4 NC
Pin 3 GND = 0
Pin 2 5v = 4.965
Pin 1 18 = 17.9

VY points read 186.9

Thanks so far!

[dick_barton]

Re: LG 60PB6600-UA No picture, whine from PSU

I would try once again to disconnect the LVDS cable going to the mainboard and short out the Auto_Gen pads with a piece of wire or paper clip and power back up to see if you get the colour patterns. Also make a note of the led flash sequence on the Logic board.

[KuroYamaneko]

Re: LG 60PB6600-UA No picture, whine from PSU

Still no patterns.
Led changed to three blinks, 1 sec on, 3 sec off, then back to previous pattern.

[dick_barton]

Re: LG 60PB6600-UA No picture, whine from PSU

I think you may have a faulty logic board. All your voltages appear to be correct and the screen test pattern is failing to come up.

At this point I would wait for others to offer their advice before replacing it.

[KuroYamaneko]

Re: LG 60PB6600-UA No picture, whine from PSU

Thanks!
I'll shop around while I wait for other input.

[KuroYamaneko]

Re: LG 60PB6600-UA No picture, whine from PSU

Just curious if anyone else had input for this. I am also wondering about the whine from the power supply.
Cheers!

[KuroYamaneko]

Re: LG 60PB6600-UA No picture, whine from PSU

Update;

I have received the logic board today. Installed it, tried turning it on. No change. Quick flash of grey, then black screen.
Any ideas?

[DXseekerMO]

Re: LG 60PB6600-UA No picture, whine from PSU

That may be a panel primer flash. Have a look at the side of capacitor C873 on the upper Y buffer board (attaches to Y-Main). See if it has a diagonal line across it or if it looks like its burnt.

I have a 6650 that once had the same symptoms, save for the noisy power supply. It's now up in my living room.

Partial pic of upper Y buffer courtesy of ShopJimmy. Cap outlined in yeller.

[KuroYamaneko]

Re: LG 60PB6600-UA No picture, whine from PSU

Thank you,
I had a look, and that capacitor has a very slight dot of discolouration. There is also one on the board below that looks burnt.
Are these smd caps able to be replaced with a soldering iron? Or does the board need replacing.

First image is upper buffer, second is below that