ves400unes-03-b chassis No picture, sound ok

[freccia]

So. I have this 40 inch led tv called Gala with the chassis ves400unes-03-b from Vestel. Closest one to it is a Hitachi 42HXT16U. It has a GA 60hz FHD Vo.3 Sticker Part No P26098d TCON Board.
Now I have measured the input voltages and they are ok.
With the other two ribbon cables connected to the panel, the voltages on the output of the t-con drop to less than 1volt.
When I remove the right ribbon cable and leave the left ribbon cable connected, the picture comes up on half the screen and white with some black thin lines on the other side.
When I connect the right ribbon cable on the t-con and remove the left ribbon cable on the output of the T-con, all the voltages go down on the output of the t-con.
Now I have a difficulty determining whether it is the T-con which is at fault or the panel, although I thing it is more that the tcon is faulty.
Can anyone help me determine which one is at fault please?
Also if it is the T-con, how can I make sure that I am ordering the correct part please?

Thanks for your help.

[dick_barton]

Re: ves400unes-03-b chassis No picture, sound ok

Post pictures of your Tcon to start off.

[freccia]

Re: ves400unes-03-b chassis No picture, sound ok

Ok I am going to post some pictures which might help show the issue. Below you will find the pictures of the t-con board and the symptoms with the two cables (blank screen only backlight), with one cable on the left (image on the left is good and white with lines on the right). If you need more information please do not hesitate to contact me. Thanks.

Photo 1


Photo 2


Photo 3


Photo 4


Photo 5


Photo 6


Photo 7


Photo 8

[freccia]

Re: ves400unes-03-b chassis No picture, sound ok

Photos 1 and 2 are of the T-con with all the cables connected. Only the backlight will show as on photo 4.
Photo 3 is the main board.
Photo 5 is a photo of the t-con without the right ribbon cable and produces a picture like the photos 6 and 8
Photo 7 is the picture from where the ribbon cable on the t-con is removed.

Thanks and hope that you find them useful in helping me resolve my issue.
If you need more info, please do not hesitate to contact me. Thanks

[dick_barton]

Re: ves400unes-03-b chassis No picture, sound ok

It does look like a panel fault. When one ribbon is removed and you have a good picture on half of the panel but does not repeat when you replace that ribbon and remove the other ribbon.

When the ribbon that does not produce the half picture is connected, is that when your voltages on the Tcon start to drop.

There is a possibility that a ceramic capacitor on the small panel board that the ribbon connector connects to (which is joined to the panel) may be short circuit.

[freccia]

Re: ves400unes-03-b chassis No picture, sound ok

Yes when I connect only the other ribbon cable, the voltages onthe output of the tcon go down, like it shuts down. What about those black lines on the other half when the screen shows half ok?
Do you think the small ceramics on the panel pcb could be shorted? I will check them just in case

[freccia]

Re: ves400unes-03-b chassis No picture, sound ok

Yes you were right. I am finding a short on all the capacitors on the thin long pcb which connects the ribbon cables of the panel to it. Found 6ohms on some and 4 ohms on others. That is why when I connect the right ribbon cable on the tcon it shorts the supplies. There is one HAVDD which is shorted for sure. Mind you this board only has resistors and capacitors on it, no semiconductors, at least I cannot see any.

Excuse my knowledge, but is there a way to check the shorted capacitors on the board without having to remove them one by one please?

Thanks once again for all your help.

[dick_barton]

Re: ves400unes-03-b chassis No picture, sound ok

is there a way to check the shorted capacitors on the board without having to remove them one by one please?

Unfortunately not that I am aware of. Others have been successful taking them off one at a time until they found the short circuit. I would lift one off, test it and then put it back if it is not shorted.
That way you won't lose the position or mix them up.

[freccia]

Re: ves400unes-03-b chassis No picture, sound ok

Ok thanks for your reply. I will have to remove them one by one then and check each until I find the culprit. I hope it is not the display which is causing these shorts but those capacitors. Will see what I can do, if I find the faulty one I will let you know for sure. You saved me from buying a tcon for nothing. Thank you very much sir for your help.

[dick_barton]

Re: ves400unes-03-b chassis No picture, sound ok

Good luck

[freccia]

Re: ves400unes-03-b chassis No picture, sound ok

Hi. I found the problem with this led tv. It wasnt the capacitors, but a ribbon cable going to the panel, and it has a driver chip on it which was shorting to chassis and is burnt. I wonder if I can find a ribbon cable for it and how I can fix the cable to the panel. Anyway at least I found the faulty component and learnt a lot from it. It is working except for those 15cm approx black screen where that ribbon cable is connected to. Thanks very much for your support Dick Burton.

[dick_barton]

Re: ves400unes-03-b chassis No picture, sound ok

Unfortunately this is not repairable without extremely expensive equipment https://www.youtube.com/watch?v=tMiLuiDSnQ4

[freccia]

Re: ves400unes-03-b chassis No picture, sound ok

Also you need to find from where you can get this special ribbon cable. I cannot find anywhere where I can get hold of it since it has a driver embedded on it in the middle.

[Andrew F. Ali]

Re: ves400unes-03-b chassis No picture, sound ok

Yes. That is the TAB/COF IC Part No. you would have to look for. It would be along one of the edges. and to repair/replace that then you would need special TAB Bonding machinery and equipment to do that operation.

[freccia]

Re: ves400unes-03-b chassis No picture, sound ok

Hi Andrew. From where do you think I can get the part number please, cos I think that it is worth a try with a lot of patience(TV is mine, not of a client). is it related to the panel size and panel manufacturer? Thanks

[dick_barton]

Re: ves400unes-03-b chassis No picture, sound ok

freccia, I believe that there is no cost effective way to replace the COF chip at this time.