Toshiba (Vestel) 50UL2063DB - bad COF?

[Russ17]

I have a Toshiba 50UL2063DB.

Most times , screen shows no image, but backlight is on.
Voltages:
Vcc = 3.3v
Vcom, Havdd, Avdd, Vgh & Vgl ate all 0v

If the right side t-con ribbon is disconnected I can see an image on the left , and get the following voltages on the screen PCB for the left (right side of screen has grey and white bars as there is no ribbon connection):
Vcc 3.3 = 3.28v
Vcom = 7v
Havdd = 7.47v
Avdd = 16v
Vgh = 24.7v
Vgh = -6.9v

If the left side t-con ribbon is disconnected I see scrambled data on the right and grey and white bars on the left as there is no ribbon connection and I get the following voltages on the screen PCB for the right side:
Vcc 3.3v = 3.28v
Vcom = 7v
Havdd = 7.48v
Avdd = 15.72v
Vgh = 24.7v
Vgl = -6.07v (this is the only voltage which is significantly different compared to above readings)

Sometimes I do get a picture with both ribbons connected but it has motion artefacts.

I have replaced the t-con board from a salved tv (identical PCB part number and tv model number) bought from an auction site, and voltages above are from after I replaced the t-con, and the symptoms are the same, so unlikely a t-con issue.

I have been tempted to remove the COF tabs on the right side of the screen (although I haven't actually disassembled the screen yet, so I am assuming it has COF tabs).
Before I do this, is there anything also I could do to confirm that this diagnosis is correct, as it is obviously a one way action.

Regards

Russ

[nomoresonys]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

not sure if it will work, but i would try the tape cut-off method, many videos on youtube covering the procedure, which is usually blocking off some contacts of ribbon cable to tcon on the bad side with non conductive tape, black electrical tape is ok.

[Russ17]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

When I can see a picture on the left, (with right side ribbon 1disconnected), the picture seems a bit washed out, with black being more grey (attached images are BBC iPlayer main page for reference, the half screen is the faulty Toshiba the full screen is a similarToshiba TV) but maybe this is simply because the right side ribbon is disconnected. Any thoughts on this?

Thanks in advance

[nomoresonys]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

washed out picture can be symptom of bad tcon, you say its exactly the same picture with both tcons?

[nomoresonys]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

Check the small ceramic capacitors on the panel driver board/s, check in diode mode for shorts, put a probe on each end, steady beep or a reading close to 000 is a short, also check in ohm mode, check for very low ohms, under 100 ohms probably isn't good, theres other components on the boards too. the caps are easy to check.

[nomoresonys]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

i suppose cof could be the problem but most times they present with horizontal lines.

[nomoresonys]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

to try to insure a match, its best to match the white sticker numbers of the tcon.

[Russ17]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

I watched a YouTube video and some threads on here, where side COF’s can cause one side to be faulty, which drags the Vgl and Vgh lines to zero volts, as in my case. Removing ALL COF’s on the faulty side restores operation, but maybe only for a limited time, but better than trashing the TV.

[nomoresonys]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

Yes it does work often when a cof is to blame but you have to make sure that is the problem, suppose the most definitive way is strip it down and inspect the cofs, the last attempt a few posts down evidently didn't go well or a bad cof wasn't the problem, most important thing is not to get in a hurry and confirm a bad cof if you can. Thats why i suggested the tests, its a process of elimination.

[dskall]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

Peeling off cof's are a one-way deal. No going back. Cutting shorted tracks are a repairable option. But more technical.

[Diah]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

hopefully you didn't cut any at the panel... for me its lack at LVDS signal specially if its single 51pins

[Russ17]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

Hi

Thanks for all the replies.

I have not cut any tacks yet or even disassembled the screen to access the COF’s , as I would prefer to eliminate all other possibilities due to risk of damaging the screen attempting to access the COF’s.

So, bearing in mind the screen occasionally works (with issues), but mostly will have no picture and all voltages are 0v (except 3.3v), what should I check for next? The Vgl and Vgh are generated on the t-con, in fact, all voltages come from t-con, there are no dc-dc converters on the panel PCB.
Voltages only drop to zero when both sides of the screen are connected.


@Diah, could you give some more detail on what signal I need to check please. I want to try isolating signals by using tape to block signals on the ribbon, but don’t know which signals to block.

@nomoresonys, thanks for the tips

Thanks to everyone else who reads this too.

Thanks

Russ

[Diah]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

LVDS Signal are Freq. depth controlled within MFC firmware part on native Linux TV platform at HD Res. and a log gamma at UHD res. , when the LVDS 51 pins or less mostly get issue with this log gamma or when the SW switched between HDR / HLG. caused corrupted at SW. and some time external cause ( such wrong part firmware installed.. or some one played with SM setting. or too parts damage on MB )

to narrow this. would be useful if you load test photos on USB with low pixel & 1920x1080 pixel & 3840 x 2160, play them on the TV while both ribbon connected and after you inspect the LVDS contact pins from both side deeply. tell which Res the screen become much stable.

also show us please clear photo of main boards and its label.

[Russ17]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

Most times, I get no picture when both ribbon from t-con to distributor PCB's are connected.
I can always get a picture on the left when the right ribbon is disconnected (pictures lacks black depth).
I get scrambled data on the right when the left ribbon is disconnected.

My first issue is getting a full picture on when both ribbons are connected.

That in itself may fix the "lack of depth" issue - maybe.
So how do I diagnose that problem with the voltages I have observed.
Coukd the LVDS 51 pin flat cable or the connection to the tcan or mainboard cause this issue?

[Diah]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

yours picture and this one too

the depth wasn't Voltage you can measure.. its Freq I2C data any corrupted will cause to (cut off / unstable signal) which drive the T-CON stop working ( destroyed or No Picture & Vgl and Vgh = 0 )

i asked photo of the Mb and its label. i don't know why users who seek help hesitated to response for others request. i cant write full story over here to explain how things work. when i did before on other threat.

yours TV if its 100% discharged it will show full picture at start up while the 2 ribbon in place.
start with hard reset with one ribbon in order to see where you click. plug off from wall discharge and re-plug second ribbon and do the test.

[Russ17]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

@diah
Thanks for your assistance, I do appreciate you donating your time to assist me.

The pictures you linked (yours picture) is the faulty tv, but I only get a picture about 1 in 20 times of switching on, almost always a blank screen with just back light glow. When there is no picture, I don't even see the Toshiba logo at startup.

If I start with right ribbon disconnected I always get a Toshiba logo and always get an image on the left.
If I start with left ribbon disconnected I never get a Toshiba logo and always get scrambled data on the right.

The picture (this one too) is a picture from a different tv, just to show the difference in picture colour. This tv works correctly.

If I understand you correctly, there is an I2C data connection from mainboard to t-con, which gives “picture data” and then from t-con to screen distribution board. I have observed a I2C chip on the t-con, with sds and scl test points, which are usually an indication of an I2C bus connection.

I have linked a picture of the component side of the mainboard (17-mb230), but the cannot get a picture of the rear just yet as the tv has been stored, but will get a picture when time allows.

I just wanted to try and confirm I understand what you want me to try.

I can get 3 different resolution pictures on a USB stick and try to show them as you requested, but I am still a little unsure about your description in the last paragraph, so could you try to explain again please, just so I can provide the information you have requested.

Thanks in advance

Regards

Russ

[Diah]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

okay so its the funny MB from Vestel 17MB230
... since you can have picture on the left side of the screen when you disconnect one ribbon do the following
while its on press Menu followed with 4-7-2-5 you will be at service menu.. shoot photo for the screen and upload here to see the panel data if it is suitable with DoVi function or not.

then go down to diagnostic/diagnose and from there you can run factory reset or too self diagnose.
if you had done the hard reset... and it went to standby . plug it off from wall and connect the other ribbon tell if you will be able to see the logo and full screen

[Russ17]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

Will do the service menu later today.

Thanks for the info

[Diah]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

Will do the service menu later today.

Thanks for the info

i would recommend you while you are at service menu..
extract the attached file and put the folder profiler on USB stick formated FAT32 insert it to the TV then call service menu and then go to USB option click on it it will dump all Tv on the usb to keep them in safe in case it need later.

[Russ17]

Re: Toshiba (Vestel) 50UL2063DB - bad COF?

Thank you very much. Will definitely do this later.