Toshiba 49U6763DA (Mainboard: Vestel 17MB120) Powers on, backlight ok, no picture

[jaifraic]

Hello,

I have a Toshiba 49U6763DA TV that shows no picture. It turns on, the backlight works, but nothing else. I don't have a remote at the moment to check if this is working.

I have opened the unit, every plug is connected, nothing seems to get hot and all caps look ok. I checked the small caps on the tcon board and the two boards that sit between the tcon and the panel (I don't know what they are called). None of the caps are shorted. The tcon board gets 12V (actually 12.5V) and the fuses are fine.

So I'm thinking that the motherboard is defective or there is a software error. I searched a bit but could not find any firmware for this unit. Does anyone know how to get it? Or could it be some other error?

The TV is from Vestel, with an LG panel. The mainboard is a 17MB120 23404925.

I would appreciate it if someone could help me. Let me know if there is any missing information.

Greetings
Jaifraic

[neilc6]

Re: Toshiba 49U6763DA (Mainboard: Vestel 17MB120) Powers on, backlight ok, no picture

TV turning on with backlight but no video, tcon board is suspect but it could be the panel. Connect only one side at a time between the tcon and panel and see if one side is good. If still no image, I would try a new tcon. Your part number is 6871L-4044D. I would search Aliexpress.

[jaifraic]

Re: Toshiba 49U6763DA (Mainboard: Vestel 17MB120) Powers on, backlight ok, no picture

Okay thanks. I've checked both sides independently and still no picture. I'm gonna look for a new tcon. Found none with the correct part no on Aliexpress, but there are a few on ebay.

[arizanotlari]

Re: Toshiba 49U6763DA (Mainboard: Vestel 17MB120) Powers on, backlight ok, no picture

Hi.

Try this firmware : https://yadi.sk/d/uAN8msJIiiU5Yw

[jaifraic]

Re: Toshiba 49U6763DA (Mainboard: Vestel 17MB120) Powers on, backlight ok, no picture

Nice. thank you.

There are four files in that zip:
mb120_en.bin
mb120_PM51.bin
RomBoot.bin
usb_auto_update_G6F.txt

Do I put all of those files on an usb drive?

I've read somewhere that the way to update is to unplug the TV, insert the usb drive, press and hold "Ok" on the remote and the power on the TV. Is this correct?

[arizanotlari]

Re: Toshiba 49U6763DA (Mainboard: Vestel 17MB120) Powers on, backlight ok, no picture

Yes.

[jaifraic]

Re: Toshiba 49U6763DA (Mainboard: Vestel 17MB120) Powers on, backlight ok, no picture

No luck with the firmware update. When I hold ok during power up it goes straight to standby. Doesn't matter if the usb drive is plugged in or not.

But with the remote I've managed to change the input, I get sound via HDMI. At least something. Gonna try a new tcon and if that doesn't work a new mb. I think this TV is worth it

[jaifraic]

Re: Toshiba 49U6763DA (Mainboard: Vestel 17MB120) Powers on, backlight ok, no picture

Okay, got a new tcon and installed it today. Now there is a picture, but it's only clear for about 2 seconds, then it flickers for 2 seconds and so on. Here's a video: https://imgur.com/a/YGmlZwl

It's not clear in the video, but the upper right part seems to flicker/change brightness even when the picture is clear. And there's a small black line visible through the middle of the panel.

I've wiggled at the cables, didn't make a difference. Wrong tcon? Or bad tcon? Bad panel?
The board is a 6871L-4044D, it was listed for a JVC LT-49C870, though.