Panasonic tx55as650b white screen.

[vikivng]

Hi guys,
just need some input on this.
Panasonic tx55as650b showing white screen on power on.
T con voltages are as follows.

FUSE=11.84
V IN= 11.83
VDD= .3V
VGH= .2V
VGL= 4.3V
VCC= 3.1V

Ill need to add more info tomoro but was hoping from these voltages something seems odd.?
Especially VGH.?
I get a constant clicking when I power on the tv.
If I remove the larger (left side of tv)ribbon cable from main board clicking stops.
Also if I remove the (right side of tv)cable on the panel side, the clicking stops.
Also I get half screen much whiter with the other half of the screen black with colored verticals if I remove the same cable (on the panel side)that causes the clicking to stop

[vikivng]

Re: Panasonic tx55as650b white screen.

Clicking seems to be coming from either main or tcon board.

[budm]

Re: Panasonic tx55as650b white screen.

Is this stand alone T-CON board or integrated T-CON on the LCD panel?
If it stand alone T-CON, what are those Voltages if the cables between T-CON and the LCD panel are not connected?

[vikivng]

Re: Panasonic tx55as650b white screen.

Is this stand alone T-CON board or integrated T-CON on the LCD panel?
If it stand alone T-CON, what are those Voltages if the cables between T-CON and the LCD panel are not connected?

Hi bud,
thnx for replying.
Yes its a standalone board.
I sense bad panel news coming ?
voltages are as follows,

V IN=11.92
VDD=15.62
VCL=5
VGH=28
VCC=3.3

[vikivng]

Re: Panasonic tx55as650b white screen.

With the left side of tv cable (panel to tcon) connected.I get the same voltages as when both cables disconnected (normal?)and the buzzing/clicking stops.
Also this is when half the screen is very white and half black with vertical lines.
Voltages go back lower with the right side connector connected and also the clicking resumes.
The whole screen also goes back to the white/grey.
I assume the problem is on the right side panel flexible board.?

[budm]

Re: Panasonic tx55as650b white screen.

You have panel problem, hopefully just some bad MLCC on the tab bonding boards, just start checking the resistance of the MLCC.

[vikivng]

Re: Panasonic tx55as650b white screen.

You have panel problem, hopefully just some bad MLCC on the tab bonding boards, just start checking the resistance of the MLCC.

Thnx ,,thought so,
should they have pretty much the same resistance of the same size.?

[budm]

Re: Panasonic tx55as650b white screen.

You will be looking for low resistance reading. MLCC failure mode is shorted or bad leakage resistance.
BTW, in theory cap has infinite resistance.

[vikivng]

Re: Panasonic tx55as650b white screen.

ok thnx