LG 65uf860 Black screen, no sound. Gets an error code from the power board

[Spu]

Hello

I have an LG 65uf860v

One morning the screen turned green/purple and then black. Before that everything was normal.

There is no backlight and no sound. If I use a flashlight I can see the screen flickering when turned on.
The t-con board makes a “high frequency sound” but not very loud.

Also on the powerboard the diode LD701 is flashing 5 times. several times. Cant find the meaning of this.
At the powerboard I get the following. All the numbers are steady.

At standby:
11 and 12 is 3,51 V

When turned on:
4 = 25,1V
5= 25,1V
7= 11,68V
8 = 11,68V
9 = 11,68V
11 = 3,48V
12 = 3,48V
13= 3,33V
14 = 3,48V


Thank you!
Stefan

[dskall]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

Unplug one ribbon at a time between t-con and panel and see if noise goes away.

[Spu]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

Thank you for your response.

When I unplug 1 at at a time:
1) Nothing happens
2) Sound changes a bit, gets a bit louder
3) Sound changes a bit, gets a bit louder
4) The noise is gets very low
5) The noise is gets very low
6) The noise goes away

[Spu]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

Do anyone have a clue what I can do and test ?

[attainteddragon]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

you have only listed half of the voltages that go to the main board. can you test the other half as well and report the voltages. use the connector where the wire harness goes to the plug.

[Spu]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

Please see the attachments.
I have listed all the voltages in both standby and when the tv I on.
Please let me know if you need anything else.

Thank you! :-)

[Spu]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

Have i listed the correct voltages for you ?

[dskall]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

There are various voltages on t-con board. Examples:

T-con voltages (typical)
1. Vin (Vcc): 12Vdc or 5Vdc
2. Vlogic,LCM, Vddd,VCC): 3.3Vdc
3. Vda (Vs, Vsource,VDD, Vdda,Avdd): 14Vdc~20Vdc
4. Vgh (Vgon,VGHR, Von, Vddg): 20Vdc~30Vdc
5. Vgl (Vgoff,VST,VGHF,VGHEVEN, Voff,Veeg): -5Vdc~-7Vdc
6. HVDD about 8v
7. DVDD,VDDC 3.3v, 1.2v
8. VCOM about 5~10vdc (about half of Avdd)

I would check and see what voltages are with 4 and 5 hooked up and disconnected to see if difference. Also check if any components on t-con getting real hot

[Spu]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

At picture 4 called "Tcon" there is a change. With 4 and 5 (the ribbons at the tcon) connected the voltages are near 0, but if I disconnect both pin 1 goes up to 3,29 V

At picture number 5 called "Powerboard" there is a change. With 4 and 5 (the ribbons at the tcon) connected the voltage at pin 2 (the black one) is near 0, but if I disconnect them, the voltage goes to 8,61 V

There a several other changes but its only a few percent. Do you need me to list them up ?

[tvsteve2]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

Please see the attachments.
I have listed all the voltages in both standby and when the tv I on.
Please let me know if you need anything else.

Thank you! :-)

You are only showing half the pins voltages (there are two rows of pins!) the second row is hidden under and closer to the connector.

[Spu]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

Here are the numbers from the powerboard. Do you need them from the mainboard as well ?

At standby:
Row 1:
Pin 11+12 = 3,54 V
Row 2:
Pin 11 = 3,54 V

When turned on:
Row 1:
Pin 4+5 = 25,4 V
Pin 7+8+9 = 11,73 V
Pin 11+12 = 3,5 V
Pin 13 = 3,3 V
Pin 14 = 3,5 V

Row 2:
Pin 5+6 = 25,4 V
Pin 8+9 = 11,73 V
Pin 11 = 3,5 V
Pin 13 = 3,3 V

[attainteddragon]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

now we can see that you have your ps/on signal and your bl/on signal.

are you positive that you have no back lights? check through the holes in the back of the set.

on the fuse of the t-con (7 amp just above the 5 pin connector), what voltage do you have on both sides of it when turned on?

[Spu]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

I made the room completely dark and turned the tv on (with no back cover). No light

The fuse at tcon is 11,7V on both sides

[Spu]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

https://streamable.com/81wk3

i have uploaded a video showing how the screen is flashing

[attainteddragon]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

right now it looks like you have 2 faults, no pic and no backlights.

can you power the set up, press the menu button, shine a torch at the screen and confirm if you have a clear image or not?

[Spu]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

At the video I am using a flashlight. nothing happens when I press the menu button (or any other buttons except power on/off). There is no clear image.

[Hamie]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

Put my mind and ease and jump the backlight on.

Seen far to many of these UF series with faulty mainbaords.

Yeah I know it is sending BL-on but just jump it anyway.

[attainteddragon]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

to jump the ps on, you will need 2x 1k resistors. we can instruct you further when you have them.

[Spu]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

Would these resistors work ?
Hamie - Do you think replacing the mainboard would fix the problem ?

Resistance:1kΩ
Tolerance: ±5%
Effekt, max.:250mW
Komponenthus: 0207
Group: C1110
Carbon Film Resistors
Series: RKB
Style: Taped
Power: 0,25W
Tolerance: 5%
Housing: 0207
Technical Specifications

Resistance Tolerance:
±5%
Power Rating (70°C):
0,25W
Operating Voltage:
250V
Short Term Operating Voltage:
500V
Insulation Resistance:
1010W
Temperature Range:
-55...+155°C

[Spu]

Re: LG 65uf860 Black screen, no sound. Gets an error code from the power board

Would these resistors work ?
Do you think replacing the mainboard would fix the problem ?