LG 50PC55 Plasma Vertical Bars!

[tom66]

Re: LG 50PC55 Plasma Vertical Bars!

It could easily cause the symptoms. "No signal" is not the fault. It is just because no input is connected.

[studfish]

Re: LG 50PC55 Plasma Vertical Bars!

Hi Tom thanks but even when i have devices connected and change the input using the controls on the tv i still get no signal.......... main board?

Also if i press the menu button the tv turns off .

The Red standby light does not change either it just goes from red to off

[studfish]

Re: LG 50PC55 Plasma Vertical Bars!

just as an update......

I changed the mainboard and now the standby light turns from red to green so there must have been some kind of problem with the original.... all other problems remain however

[tom66]

Re: LG 50PC55 Plasma Vertical Bars!

Could just be different config/software on main board. Doubt main board was bad. 99% Y-buffer, 1% Y-sustain (if -Vy or Vsc askew.)

[Glitcher]

Re: LG 50PC55 Plasma Vertical Bars!

Common problem would be a blown IC on one of the buffer boards. Just a guess but it is a FQB46N15? If it is then replacing it should fix the problem.

[studfish]

Re: LG 50PC55 Plasma Vertical Bars!

gone over the power supply with a fine tooth comb and found a bulged 250v 820uf cap (dont ask how i missed it) guess that need replacing before i go any further

[Alastair E]

Re: LG 50PC55 Plasma Vertical Bars!

IF you have Vertical bars on the pic, then there's a high chance the Address Chip associated with that area of the screen is stuffed.

These chips are found along the Bottom edge of the screen and are often part to the flexible connection to the screen--and are part of the screen and not replaceable.
--If so, then you'll need a new plasma panel......

The dead/int dead could well be a protection system coming in due to the stuffed chip....

[studfish]

Re: LG 50PC55 Plasma Vertical Bars!

Im still after getting this tv repaired so i have uploaded a short video of the problem I would appreciate it if someone could tae the time to have a look
Thanks
Kev

[studfish]

Re: LG 50PC55 Plasma Vertical Bars!

Ive just checked the va and vs voltages and wondered if there within tollerance?

The va is suppose to be 60 but is reading 55.2
The vs is suppose to be 190 and is reading 188.6

[Glitcher]

Re: LG 50PC55 Plasma Vertical Bars!

One of your Y-Buffers are bad... You need to replace the blown FET IC on it.

If you find that after replacing the FET, the problem is still there, you need to check it again as it may have blown again.

Its a common problem and usually the FET will blow again if your Y-Sustain is starting to go bad.

[studfish]

Re: LG 50PC55 Plasma Vertical Bars!

Thanks the top y-buffer is bad so ive done the va vs test with them dissconected would this make a difference?

[Glitcher]

Re: LG 50PC55 Plasma Vertical Bars!

I don't think the VA or VS voltages would change whether or not the buffers are disconnected.