Cloudy White Screen = dead TCON board?

[eccerr0r]

Well, I got my first dead TV to repair or part and dispose of. Boo. Hate it when I acquire other peoples repair failures.

The TV turns on but is silent, CCFLs turn on, but I get the "cloudy white" display. I take it that the TCON is bad since the PSU appears to be working since it has soft power which works...

The TV uses an integrated TCON as far as I can tell. So theoretically I have to ditch the panel with the TCON to fix it?

Are tcon boards fixable or do they tend to be complete FRUs? How much state is kept on tcon boards? Chances of just a power connection to the tcon gone bad that would cause the cloudy white screen, or is there initialization that needs to be done on the tcon (and thus a microcontroller there too) which could have all sorts of annoying things that could go wrong with it that would emulate no power?

[nomoresonys]

Re: Cloudy White Screen = dead TCON board?

Make, full model number and pics.??

[eccerr0r]

Re: Cloudy White Screen = dead TCON board?

Ah sorry was more of a general question. Don't have pictures, kind of mad at it, threw it somewhere to look at it later or never, but it's some crappy polaroid brand 19".

Cloudy white display as in the TFTs in the display all are off/not controlled, so whatever state they were in is what they are - no picture information whatsoever is making it to the display. Blooms everywhere, just like clouds... Eventually fades to mostly white.

The pinout of the cable from the logic board to the tcon would be interesting of course for probing, but getting this kind of data is never easy...

[Dannyx]

Re: Cloudy White Screen = dead TCON board?

Blooms everywhere, just like clouds... Eventually fades to mostly white.

Sounds like a bad panel to me, though I haven't fixed a TV in ages now

[Davi.p]

Re: Cloudy White Screen = dead TCON board?

It seems mainly a tcon defect, you must check the usual tensions on it...

[nomoresonys]

Re: Cloudy White Screen = dead TCON board?

Does seem like a panel issue from description, could probably find a cheap tcon but would only work if it is a tcon issue of course, wouldn't think they would cost too much, being that it's 19 inches.

[eccerr0r]

Re: Cloudy White Screen = dead TCON board?

What about the integrated tcons? Usually means I replace the tcon with the panel? Then the ones that are chip-on-cable (though I think this one there's a board on the display.)

Anyone actually try repairing tcon boards or are they pretty much needing to swap them because there's not much that is fixable on them (i.e. broken PCB trace somewhere or the ICs are toast?)

[Davi.p]

Re: Cloudy White Screen = dead TCON board?

Check first if the tcon supply tension 12v or 5v stay there, or if the fuse is broken, if not you can check for the dc-dc converters, switching or not.. how? this is another story..

[eccerr0r]

Re: Cloudy White Screen = dead TCON board?

Cool yeah I did notice a device I wasn't familiar with - a 4-pin TO-220 remote controllable 12V LDO on the PSU board. As I didn't have schematics and the silkscreen sucks on this board I didn't trace it - if it even feeds the tcon or not.

I should go due diligence and test the voltages on the psu board, though testing on the tcon board is going to be mighty difficult. There were a bunch of bad caps on the board I didn't bother replacing because I was expecting different behavior from the device due to the bad caps, not the white out.

[Davi.p]

Re: Cloudy White Screen = dead TCON board?

change them..

[budm]

Re: Cloudy White Screen = dead TCON board?

We need to see the pictures so we can see what we are really dealing with.

[nomoresonys]

Re: Cloudy White Screen = dead TCON board?

This is the missing info we needed, change m out, it's probably your only problem, bad caps can give all kinds of displays that can make you think it's something else.

[Dannyx]

Re: Cloudy White Screen = dead TCON board?

I once had a Samsung TV which had a semi-dead LDO on its T-con, hence it didn't produce any picture - just a white screen. Its output was slightly less than what its package said. Since I didn't have the exact part on hand at that moment, I first wanted to check if that was the issue to begin with, so I removed the LDO and wired in a cheap DC-DC buck converter off Ali set to 3.3v if I remember correctly. The set did produce an image, albeit it had horizontal stripes all over it because it didn't like the switched output of that converter - wasn't filtered well enough. Still, it instantly told me what the issue was and I got the proper LDO which solved the issue. I actually wrote a thread about this and it's you guys who told me what the issue was all along. Might not be completely similar to what you describe, but goes to show bad power CAN cause issues at panel-level where you don't usually expect it to...

[eccerr0r]

Re: Cloudy White Screen = dead TCON board?

Interesting. Might have to check after all. Just that the behavior didn't seem right, I'd expect mostly working but random cyclic behavior with bad caps, at least that's all the other bad cap problems I've seen on my LCD monitors (other than the switch controller capacitor which could cause even power up to fail -- neither of these behaviors match what I saw with my LCD monitors prior to replacing the bad capacitors.)

Will need to dig the TV out of the defer pile... and the LDO is a 12V (278R12) unit which sort of baffles me.

Incidentally the cloudy white screen is the exact behavior I saw with my LCD monitors if I forget to connect the logic cable from the digital board to the tcon/panel.

[Davi.p]

Re: Cloudy White Screen = dead TCON board?

The cloudy effect is probably due to an initial power up of the panel, then tcon goes protection, the pixels has a gate capacitance that lets those to slowly fade to white (off).

[mateuszdg]

Re: Cloudy White Screen = dead TCON board?

We need to see the pictures so we can see what we are really dealing with.

Sorry for jumping in i alaway tought its a panel issue. I have screpped one sony for that issue. Now i have a nice big OLED sony with simmilar issue and i wonder if its for sure panel. Any advices ?

Its SONY 65AF9 and it powers on with almost black screen except part of it is like cloudy gray.

[Diah]

Re: Cloudy White Screen = dead TCON board?

Sorry for jumping in i alaway tought its a panel issue. I have screpped one sony for that issue. Now i have a nice big OLED sony with simmilar issue and i wonder if its for sure panel. Any advices ?

Its SONY 65AF9 and it powers on with almost black screen except part of it is like cloudy gray.

we have threat on sony OLED and its described how to test panel and t-con as stand alone.. make new threat and show us yours test result

[mateuszdg]

Re: Cloudy White Screen = dead TCON board?

we have threat on sony OLED and its described how to test panel and t-con as stand alone.. make new threat and show us yours test result

I would love to do it but i cannot create my own new thread even tough i have met all requirements and been already in few discussions etc WHo do i need to talk about it ?

I was trying to find a dedlcated thread for Sony OLED but unsuccesfull. Any chance you could share a link ?

Thank you very much.

[EazyBone]

Re: Cloudy White Screen = dead TCON board?

I had a Sony 5 blink thread. It's pretty recent, shows how to test the panel there. Diah explains it. My panel unfortunately was dead, but the test is valid

[mateuszdg]

Re: Cloudy White Screen = dead TCON board?

Coud anyone help me finding a OLED test thread? I was searching for it but no luck. I'd like to finally rule out screen from other components. Thx