Sony KDL-50w829b

[ronhayes]

Hi All
I know this is a long shot as from what i have seen with these sets the LCD panel are of very poor standard.
This set comes on when powered up and when i connect a DVD player via scart i get sound but no picture just a black screen.
I have tried two t-con boards but still no results same black screen with all three t-con boards ?
I have tried removing each ribbon from t-con to panel which does nothing at all the screen stays the same ? I have tried this several times and at one time i did get half of a picture with one of the ribbons unplugged and it was a good picture very clear. But when i reconnected the ribbon it went back to a black screen and it does not matter how many times i have tried to remove the ribbons i just can't get it to display half of a picture again you can see the backlights are on.
I have also connected my lcd tester to the t-con board and switched on but you need to disconnect the lead from the power board to get the backlights on with the lcd tester connected but can not get any test patterns to display.
I am aware that these sets are prone to lcd failure.
I have even tried flexing the screen but nothing.
I am including some pictures and one is of two t-con boards as i had to return one to supplier as it gave me a red flashing light when connected.
I have read in some posts that you can put tape over a certain track on the ribbons and this would give you a picture but have never done this and would not know which tracks to isolate ? If this was possible any pointers as to which tracks i would need to isolate or do you think this lcd is toast ?

Any help would be much appreciated.

[dick_barton]

Re: Sony KDL-50w829b

Have you shone a bright light on the screen to see if there is an image or do the backights come on when playing the DVD with no image displayed. Is there an image when you use the Panel Tester again shining a light on the screen?

[ronhayes]

Re: Sony KDL-50w829b

There is defiantly no picture as the backlights come on you actually see the screen light up but no picture not even with the lcd tester connected.

[dick_barton]

Re: Sony KDL-50w829b

Have you checked that you have voltage at the tcon fuse?

[ronhayes]

Re: Sony KDL-50w829b

Yes 12.5v

[vinceroger69]

Re: Sony KDL-50w829b

https://www.youtube.com/watch?v=j7vl7-vZEL8

[ronhayes]

Re: Sony KDL-50w829b

After removing the right ribbon looking at the back of tv then powering up i get what you see in the attached photo's but when re-fitted the screen slowly goes black again , then if you remove the left ribbon and power up the screen stays black.

[ronhayes]

Re: Sony KDL-50w829b

Could any one tell me if i get picture to one half of screen but not other does this mean that the lcd panel is ok ? and the t-con board is at fault ?

[vinceroger69]

Re: Sony KDL-50w829b

there is a pcb board bonded to the lcd panel, theirs been a few cases where a smd capacitor/etc has shorted out and caused no screen image on that side of the lcd panel

[ronhayes]

Re: Sony KDL-50w829b

Ok so now i have removed all the fixtures to expose these boards.
Now what i need is a schematic to give me the values of these components for me to test them !! If any one could help with that?

[vinceroger69]

Re: Sony KDL-50w829b

Can you upload a picture of that board ron, the few i have seen you can usually test the components on say the left of the pcb and then compare same parts on the right hand side, this may not even be your issue with your tv like you say it could be a tcon/lcd panel/tab bond fault,but it has been mentioned in a few threads. Does anything get hot on the bad side of the panel pcb?

[ronhayes]

Re: Sony KDL-50w829b

Hi Vinceroger69
Here are a photo of each board hope they are clear enough to see ?
When you say does anything get hot do you mean by running your finger along board when ribbon is connected and tv on ?

[ronhayes]

Re: Sony KDL-50w829b

I can't feel anything getting hot ?

[vinceroger69]

Re: Sony KDL-50w829b

im not sure then, maybe a more experienced member will have some more tests you can carry out maybe it is a lcd panel failure?

[ronhayes]

Re: Sony KDL-50w829b

Yes Vince maybe you are right it may well be the lcd panel but now i have stripped it down this far would be interested in checking the components on these boards to see if any have failed? a schematic would be handy.
It seems all to common now with these new smart TV's lcd failure !! How can these manufacturers be allowed to get away with the crap they are now producing !
When flat panels were first produced they would be good for ten to fifteen years now all the manufacturers are giving is a one year warranty and you are lucky if their new products last two years.
This is no doubt so buyers would have to replace more often even more money in the manufacturers banks.
Sony used to be a name to look up to but sadly not any more.

[vinceroger69]

Re: Sony KDL-50w829b

hopefully a more experienced member may of seen this issue before and give some advice , did you try a replacement tcon board?

[budwich]

Re: Sony KDL-50w829b

you need to look at the tab bonds that attach to the panel ... ie. the other side of the panel that you are showing. further, connecting / disconnecting the tcon to panel cables while powered is probably not a great idea depending on how well / steady your effort is since there are powering pins happening in very small spaces.

finally, the fact that you get some form of picture with one cable attached while the "opposite" scenario gets you nothing indicates that the "opposite" has significant issues.
Having said that even the "one working scenario" gives you a "less than good picture" isn't a good sign also.... especially seeing vertical lines.

can you provide some history of the set. My first guess is that someone was washing the screen and has contaminated the tab bond connections either at the edge boards or at the panel edge itself.

still further, you can do some simple testing / checking of the components on the edge boards by just comparing results between the two sides / halves... concentrating on capacitors and resistors.

[ronhayes]

Re: Sony KDL-50w829b

Yes Vince
I sent for one that did not produce a picture so i ordered another thinking that may be it was also faulty, when that arrived and i installed it gave me a red flashing light so i contacted the supplier (spares2repair) and they sent me a replacement one out and that was the same no picture !
So maybe i have had all faulty t-con's or maybe it is lcd panel the only way i would be sure is if i tried a guaranteed new t-con board.
But that would be another costly chance to take.

[ronhayes]

Re: Sony KDL-50w829b

Thanks for the info budwich looking at the panel with all the trim removed the bottom edge looks very clean no stains at all and the tab bonds are on the back of the screen so would have to completely remove screen to check the tabs, looking closely at the removed trims there is no sign of water stains at all.
I fear to completely remove the screen would be a bit tricky maybe i am wrong.
I am now getting ready for work as i am on nights this week .

[budwich]

Re: Sony KDL-50w829b

I don't believe you have to "completely remove the screen" (don't know on this set... I worked on a 46). there was a metal bezel going around the screen that has a "dozen" screws holding it in place. The set / panel needs to be sitting face up. the bezel lifts off and exposes all the panel connections that need to be looked at. The pictures that you show of the tabs do not show the connections at the panel so its hard to tell if there are issues there.

further... what is the history of the set?