Sony KDL-55W828B Hotspot in LCD panel

[PlanB]

Hello everybody,

I need your expertise if my asumption about the failure of this TV is correct.

A Sony KDL-55W828B only shows vertical red stripes that vanish to the top when switched on.
When only the right side of the LCD is plugged into the T-CON board the right side shows a good image, while the left side is white.
When only the left side of the LCD is plugged into the T-CON board the LCD shows a complete white image.

I checked some signals on the T-CON board but was not able to find something strange. Then I checked the the caps on the LCD driver board and all seem fine (values > 150 Ohm or even some kOhms in resistance mode).

After that I used the tape method to block some signals on the left side connecter and really one connection made the difference and I got a complete picture, but it had some horizontal lines in it.

With a thermal cam I found a very small hotspot on the lower left corner of the panel which got temperatures of over 130 °C. I also checked if this hotspot may be behind the panel, but it is really in the LCD panel. Right side of the panel is fine and only got temps to 30ish °C.

Am I right that this panel is defect and there is no hope for a fix?

This is my first TV repair attempt, therefore I would ask for your expertise.

Thanks
Ben

[dskall]

Re: Sony KDL-55W828B Hotspot in LCD panel

If the bad trace is going to a side tab you can bypass with a thin wire. Many videos on this.

[PlanB]

Re: Sony KDL-55W828B Hotspot in LCD panel

If the bad trace is going to a side tab you can bypass with a thin wire. Many videos on this.

Thanks a lot for this hint! I never heard about this method.

As far as I understood it from the videos, this is when a voltage is missing directly at the panel tabs. When there is a hotspot in the panel, this looks more like a short for me. Could this short also be in the side tabs?

I will give it a try, maybe I find something during inspecting the tabs

[dskall]

Re: Sony KDL-55W828B Hotspot in LCD panel

If it's a short between traces on the glass. you will have to bypass those lines.

[PlanB]

Re: Sony KDL-55W828B Hotspot in LCD panel

If it's a short between traces on the glass. you will have to bypass those lines.

I removed the side covers which hold the lcd panel, but there are no additional tabs on the left or right side of the panel. The only tabs are on the bottom attached to the driver board and and could not find any short there.

But with the whole panel exposed I could precisely locate the hotspot in the edge of the panel (see attached image).
I also found that some of the 75 Ohm resistors on the panel driver board also get very hot (see attached images). I removed them one by one to see if there is any change, but the hotspot in the corner still persits. I also have to admit that I don´t know what those lines are. As this are 75 Ohm resistors I suspect that it´s for impedance matching of the lvds signals.

Any further suggestions? Even when it will be no fix, I hope to learn something about what I´m doing wrong or I didn´t understand.

Thanks

[dskall]

Re: Sony KDL-55W828B Hotspot in LCD panel

If you have no side tabs, the only thing you can do is keep disconnecting traces till you find short. It's possible you may get picture back minus some resolution.

[PlanB]

Re: Sony KDL-55W828B Hotspot in LCD panel

If you have no side tabs, the only thing you can do is keep disconnecting traces till you find short. It's possible you may get picture back minus some resolution.

Thanks a lot dskall!

I got a picture back by the tape method. But there were significant horizontal lines visible so that the picture is not useable anymore.

So I decided to take the panel out to take a look at the backside on the hotspot area and was able to take a picture of it with my microscope (see attached image). Seems that the damage is to heavy to get a usable picture back from the panel.

That was an exciting first TV repair attempt and I learnd a lot. Thanks

[dskall]

Re: Sony KDL-55W828B Hotspot in LCD panel

Well, this was an unrepairable problem even for the best techs in India.