Sony KDL55EX720 won't turn on

[tibimakai]

Re: Sony KDL55EX720 won't turn on

I have replaced the 5 pin VDO at the STBY on the PS.
Replaced the main board and it shows the 5 x error code.
I have tried a shopjimmy T-con, but did not changed anything, so I have sent it back.
With the old main board, the TV seems dead. Most likely, something got damaged, since the VDO was damaged.

[budm]

Re: Sony KDL55EX720 won't turn on

I look at the larger service manual PDF page 106 flow chart for 5X, iit said to check pin1 CN6001 panel_vcc on B board for 12VDC. Do you see that 12V for seconds?

[tibimakai]

Re: Sony KDL55EX720 won't turn on

I'm not in front of the TV right now, but I will measure it in the morning.

[tibimakai]

Re: Sony KDL55EX720 won't turn on

OK, I'm at the TV right now.
I'm having hard time finding pin #1 at CN6001.
Pin one(there is a dot on the PCB trace) it doesn't have a wire in the connector.
The second pin shows 12.67V in standby and if I turn it on, it drops toward 0V.
On the other end of the connector, there is 3.2V, so it must be that 12V then.
On the power supply there are three pins, T_Con_VCC_12V which are going to the T_con and it turns on for a blink of the second to 12.65V measured with MinMax.

[budm]

Re: Sony KDL55EX720 won't turn on

Boy, the diagrams are very bad due to very poor resolution, getting headache trying to trace out the SCH.

[tibimakai]

Re: Sony KDL55EX720 won't turn on

They made it intentionally this way, imho.

[tibimakai]

Re: Sony KDL55EX720 won't turn on

I can't even find the B board.
I'm looking at page #126, BATV board connections and I don't see any panel-Vcc there with pin #1 marking.
I'm not sure, if that flow chart it's for my TV.

[tibimakai]

Re: Sony KDL55EX720 won't turn on

Bud, there has been a development.
I have found a bad fuse on the T-con, the other one it still good.
This is weird, because I have checked it before and it was good.
The TV still did not start up after this replacement. I have replaced it for now with a 3A one and not a 5A as the original one.
Then I have tried removing the ribbons from the panel and the TV started up with the green and yellow LED blinking.
I have thought that maybe I should try the firmware update and it seemed like it worked. The LED on the USB stick it was flashing for a couple of minutes, the the LEDs switched to orange and red, they were solid for a while and then restarted and stayed on on green LED and the backlight turned on and stayed on.
I thought that I have fixed the TV.
But when I connected the ribbons, the same 5 x error showed up.
It must be something bad on the panel pcb or the panel is shorted.
What do you think, what else can I do?
There is anything on the panel board(s) that can go bad?

[budm]

Re: Sony KDL55EX720 won't turn on

If so right now the 12V on the T-COB fuse is still present for seconds and then drop out? You can try disconnecting the cable between the T-CON and the LCD panel to see if the TV will stay on.

[tibimakai]

Re: Sony KDL55EX720 won't turn on

If I disconnect one ribbon from the panel, the TV works, but as soon as I connect the second ribbon, the TV goes back to 5 error blink.
At this point, it looks like a shorted panel.
But, I'm thinking that since the standby voltage was to high, maybe something got damaged on the panel's board?

[budm]

Re: Sony KDL55EX720 won't turn on

It sounds like some thing in the panel is drawing too much current. So either one connected at a time the TV will stay on?

[tibimakai]

Re: Sony KDL55EX720 won't turn on

One side works and the other side causes 5 x error code.

[budm]

Re: Sony KDL55EX720 won't turn on

OK, that is what I expect, I did not expect both will be bad. BTW, do get to see the picture on half the screen?

[tibimakai]

Re: Sony KDL55EX720 won't turn on

Yes, there is an image, right side it's working.

[budm]

Re: Sony KDL55EX720 won't turn on

Well I am glad you found the cause of the problem, so next time we know that fault in the panel can cause 5X error, noted that in my library of possible cause. It may have bad ceramic caps on the long board on top of the panel or shorted out TFT driver ICs on the flex PCB.
I also wonder which signal line on the LVDS cable is used for the error signal to tell the main board that there is problem int he T-CON, LCD panel.

[tibimakai]

Re: Sony KDL55EX720 won't turn on

I guess, I need to take it apart.
I have this 65" Sharp with faulty inverter that is in my way.
I may have to repair that first, to be able to work on this Sony.
How does it "look" a bad ceramic capacitor, shorted? I have to test them with Ohm meter?

[budm]

Re: Sony KDL55EX720 won't turn on

If they have the ceramic cap (MLCC), they are light brown color with rectangular shape. I am sure you have seen them before. You use Ohm meter to test for short or low resistance, they typically fail in shorted out mode.

[tibimakai]

Re: Sony KDL55EX720 won't turn on

There is a possibility, that these caps can be bad and causing this issue?
I had a Samsung 3D TV before, with the same symptoms and I have sold it, without even checking the panel boards.

[budm]

Re: Sony KDL55EX720 won't turn on

Caps or the TFT IC which is on the flexible PCB.
https://www.badcaps.net/forum/attach...1&d=1357462883

TFT driver IC, small rectangular mounted on the flexible PCB.
https://www.badcaps.net/forum/attach...8&d=1357462883
They run hot.
https://www.badcaps.net/forum/attach...0&d=1357462883

[tibimakai]

Re: Sony KDL55EX720 won't turn on

I have worked with these and I know they run very hot, but I don't have experience with the capacitors.