Please LG TV no picture but sound slight buzzing

[budm]

Re: Please LG TV no picture but sound slight buzzing

1) So if you power up the TV now, do you hear the buzz coming from the inductors, with 220 printed on top?
2) now you need to take the DC Voltages on those test points to see what you have.

[Fixing222]

Re: Please LG TV no picture but sound slight buzzing

1) So if you power up the TV now, do you hear the buzz coming from the inductors, with 220 printed on top?
2) now you need to take the DC Voltages on those test points to see what you have.

1. I think so hard to tell
2.
VDD 7.0 -7.3 (changing)
VGH 3.6
VCC18 1.87
VGL 4.9
VIN 12.12
HVDD 3.3-3.5 (changing)

[budm]

Re: Please LG TV no picture but sound slight buzzing

1. I think so hard to tell
2.
VDD 7.0 -7.3 (changing) ????
VGH 3.6 This Bad
VCC18 1.87
VGL 4.9. This should be Negative number.
VIN 12.12
HVDD 3.3-3.5 (changing)

Typical T-CON Voltages
1. Vin: 12V (we confirmed as present)
2. Vdd (Vlogic, Vddd): 3.3V
3. Vda (Vs, Vsource, Vdda Avdd): 14V to 20V
4. Vgh (Vgon, Von, Vddg): 20V to 30V
5. Vgl (Vgoff, Voff, Veeg): -5V to -7V


Measure them aging without any cables between T-CON and the panel connected.

[Fixing222]

Re: Please LG TV no picture but sound slight buzzing

Typical T-CON Voltages
1. Vin: 12V (we confirmed as present)
2. Vdd (Vlogic, Vddd): 3.3V
3. Vda (Vs, Vsource, Vdda Avdd): 14V to 20V
4. Vgh (Vgon, Von, Vddg): 20V to 30V
5. Vgl (Vgoff, Voff, Veeg): -5V to -7V


Measure them aging without any cables between T-CON and the panel connected.

I got a new t-con through today and the same buzzing but flashes from the screen/backlight front of tv you were right i shouldn't have tested the t-con but hopefully nothing done if its repairable at all.

Without the panel conected to the t-con there are flashes every couple of seconds now maybe i messed it up

edit i seen these before im sure actually so i think nothing new also slight hardly hearable noise from power board squealing that might be important or normal (maybe the copper coil

VDD 15.84
VGH 2.7
VCC 1.203
VGL -5.01
VIN 12.12
HVDD 7.91

[budm]

Re: Please LG TV no picture but sound slight buzzing

Well, too bad you put in the new T-CON board without testing those Voltages first without the ribbon cables between T-CON and LCD panel connected.
That VGH is being loaded way down.
"Without the panel connected to the t-con there are flashes every couple of seconds" What does it mean 'flashes every couple of seconds', what flashes?

[Fixing222]

Re: Please LG TV no picture but sound slight buzzing

Well, too bad you put in the new T-CON board without testing those Voltages first without the ribbon cables between T-CON and LCD panel connected.
That VGH is being loaded way down.
"Without the panel connected to the t-con there are flashes every couple of seconds" What does it mean 'flashes every couple of seconds', what flashes?

From the backlight like a black light on the screen for a second and yes not connected to tcon (two bottom ribbon cables) its strange.
Also edited post above about whining coil maybe on power board it was since yesterday i noticed it as its quiet

[budm]

Re: Please LG TV no picture but sound slight buzzing

VGH should be in the 20V (Typ.) without LCD cables in place. You only getting 2.7V

[Fixing222]

Re: Please LG TV no picture but sound slight buzzing

VGH should be in the 20V (Typ.) without LCD cables in place. You only getting 2.7V

So could be powerboard or the other board but as slight whine from the powerboard coil maybe replacing powerboard would fix?

Also i put the old t-con on and get 27v. I see i read the measurment wrong

[budm]

Re: Please LG TV no picture but sound slight buzzing

So could be powerboard or the other board but as slight whine from the powerboard coil maybe replacing powerboard would fix?

Also i put the old t-con on and get 27v. I apologize maybe i was in standby with other t-con

So VGH is now 27V with ALL the cables back in place? same with the new T-CON board?
Also for clarification:
1) with old T-CON board in place, the backlights NEVER come on with or without the cables between TCON and the panel, correct?
2) The new TCON, now the backlights come on for seconds with or without the cables between TCON and the panel, correct?

"Also i put the old t-con on and get 27v. I apologize maybe i was in standby with other t-con" That will be impossible since you are getting other Voltages, in standby there will be no 12V feeding the TCON.
So at this point we need accurate data to troubleshoot the problem, right now the data is not correct or consistence.

[Fixing222]

Re: Please LG TV no picture but sound slight buzzing

So VGH is now 27V with ALL the cables back in place?

I will try putting all back now, 3.4 v i see what you mean, panel looks bad? or maybe a backlight?

[Fixing222]

Re: Please LG TV no picture but sound slight buzzing

[QUOTE=budm;908420]So VGH is now 27V with ALL the cables back in place? same with the new T-CON board?
Also for clarification:
1) with old T-CON board in place, the backlights NEVER come on with or without the cables between TCON and the panel, correct?
2) The new TCON, now the backlights come on for seconds with or without the cables between TCON and the panel, correct?

Just tested the backlights comming on with both boards maybe as the room is dark i can see now

[budm]

Re: Please LG TV no picture but sound slight buzzing

I will try putting all back now, 3.4 v i see what you mean, panel looks bad? or maybe a backlight?

At this point we need to find out what the VGH Voltage is for BOTH T-CON boards with and without the ribbon cables between the panel and the T-CON.
"Also i put the old t-con on and get 27v. I apologize maybe i was in standby with other t-con"
BTW, so how did you get the VGH of 27V then? and now it is 3.4V
Very confusing.

[Fixing222]

Re: Please LG TV no picture but sound slight buzzing

At this point we need to find out what the VGH Voltage is for BOTH T-CON boards with and without the ribbon cables between the panel and the T-CON.
"Also i put the old t-con on and get 27v. I apologize maybe i was in standby with other t-con"
BTW, so how did you get the VGH of 27V then? and now it is 3.4V
Very confusing.

Sorry 27v without pannel connected, 3.4 when i connect the 2 ribon cables, Same on both i think.

The flash like on this video https://www.youtube.com/watch?v=Fva__AeWMW0 at 10:15 maybe same cause.

[budm]

Re: Please LG TV no picture but sound slight buzzing

Sorry 27v without pannel connected, 3.4 when i connect the 2 ribon cables, Same on both i think.

The flash like on this video https://www.youtube.com/watch?v=Fva__AeWMW0 at 10:15 maybe same cause.

At this point based on your reports, there is problem in the panel that is pulling down the VGH power supply on the T-CON board.

[budm]

Re: Please LG TV no picture but sound slight buzzing

Your post #20
All displayed as k measurement on my UT118A auto select
VDD 2.295
VGH 8.79
VCC18 1.080
VGL 1.498
VIN 8.13
HVDD 1.135
Are you 100% sure that VHG is 8.79 K Ohms with all cables in place?

[Fixing222]

Re: Please LG TV no picture but sound slight buzzing

Your post #20
All displayed as k measurement on my UT118A auto select
VDD 2.295
VGH 8.79
VCC18 1.080
VGL 1.498
VIN 8.13
HVDD 1.135
Are you 100% sure that VHG is 8.79 K Ohms?

On both boards yes VGH is showing 8.8k ohms

[budm]

Re: Please LG TV no picture but sound slight buzzing

On both boards yes VGH is showing 8.8k ohms

With all cables in place, correct?

[Fixing222]

Re: Please LG TV no picture but sound slight buzzing

With all cables in place, correct?

Yup just tried both boards

[budm]

Re: Please LG TV no picture but sound slight buzzing

Well, that is not low DC static resistance enough to load down the VGH power supply, so it is more likely to be active device, I.E. COF, that is loading down the VGH line. At this point I do not know what else to tell you, may be taping off method, I.E. tape off some of the pins on the connector on the T-CON to panel. Do the search on the forum.

[budm]

Re: Please LG TV no picture but sound slight buzzing

BTW, I also expect the backlighst to come on (if all the Voltages and Control signals are present on the power supply board) when both ribbon cables between T-CON and the panel are not connected, so that may be another issue beside bad VGH Voltage.