KDL-43W805C - backlight and sound work but no picture

[budwich]

Re: KDL-43W805C - backlight and sound work but no picture

so there appears to be some difference between the sides in terms of results. The left seems somewhat expected while the right seems not so much so. If anything, IF things were OK at or around the panel, I would expect to same responses to appear on both side... just a gut feel and kind of based on past experiences / reads of this type of test.

Potentially the VGHD does not look good. Were these measurement done with both cables attached? Was there any picture at the time? My guess would be no picture, no voltage.

Not sure how much more time you want to spend on things, but the next step, would be to get at the bottom edge boards... oh one other thing about the measurements, how were you able to measure things and still have the main board over top of the tcon? Does that mean you are doing things at the bottom edge boards?

Your last post and my post "past in the night".... yes the "tape cutoff" method might work to help with getting some display. You need to put a small bit of tape on the one ribbon (probably right side) at an appropriate area to block some of the signals on that side. Usually, toward one side of the ribbon or the other... experiment.

[Dobsuk]

Re: KDL-43W805C - backlight and sound work but no picture

Potentially the VGHD does not look good. Were these measurement done with both cables attached? Was there any picture at the time? My guess would be no picture, no voltage.

Yes, both cables were attached.

......... oh one other thing about the measurements, how were you able to measure things and still have the main board over top of the tcon?

Do not ask me about the measurements I took them somehow from the TCON board keeping the main board with my other hand. And this is the reason why i was not able to check if i there is picture or not.

I took the measurements with both cables disconnected and the results are the same

You need to put a small bit of tape on the one ribbon (probably right side) at an appropriate area to block some of the signals on that side. Usually, toward one side of the ribbon or the other... experiment.

Yeah, i did that but without success.

One more ting which i found today. When i have the TV lying down - screen faced to the table i can see the normal picture more often than if it is normal position. For example - i've had the TV in normal position since yesterday i did not see picture at all after my last reset. I tested in thousands time but nothing. Today i put it lying down and i can see normal clear picture more often now. I now it is weird.... BTW - yesterday when i did the software update etc.. the tv was upside down....

[budwich]

Re: KDL-43W805C - backlight and sound work but no picture

ya... pretty weird. Try upside down again... maybe the bits are falling in the opposite direction... :-)

This is very much like TCL /roku set a while back.

I would suggest you trace / track where the one voltage that was 0 travels to a point that you can readily get out with the set positioned normally. Do your thing to try get a picture and measure that value. Having said that, you would still need to know why "positioning" might impact the result. My guess would be a panel issue resulting in a trace / track problem.

Related to the TCL one, that poster found that placing a finger in / near a SMD capacitor on the edge board seemed to cause a picture some times. Hence, you might look at the bottom edge boards to see what's happening there. Picture may help.

[nomoresonys]

Re: KDL-43W805C - backlight and sound work but no picture

Check the solder joints on the mainboard, sometimes a joint will get connection in a certain position, check them closely, maybe wiggle some, see if they are loose, a magnifying glass is helpful.

[Dobsuk]

Re: KDL-43W805C - backlight and sound work but no picture

ya... pretty weird. Try upside down again... maybe the bits are falling in the opposite direction... :-)

OK, So, it was with screen down facing the table and it was working normally about 1 hour. Then i turned it upside down (back side to the table) and it was still working. In 15 mins i decided to put it in normal standing position and it was still working - about 3 hours, nice and clear picture.

Then i switched it off and on few times and it seemed to work ok. Now will see how it will be tomorrow. I believe it is something about the bottom edge boards as well. I will check them once it stops work again.
One more thing which i noticed now - Before that when i had problem with the picture and I was doing some tests, measurements etc. i found that the bottom edge of the tv is getting warmer. Not too hot but warm. I thought it is normal. But now after 3hrs working the bottom edge was nice and cold. One more reason to make me think about the problem with that connections on the bottom boards.

Do your thing to try get a picture and measure that value.

Check the solder joints on the mainboard, sometimes a joint will get connection in a certain position

I will do this checks once when it stops work again, guys. Just keep doing some test tomorrow. I am confused now and do not know what to think

[budwich]

Re: KDL-43W805C - backlight and sound work but no picture

the voltage measurement needs to be done when it is working and then again when it stops.

[nomoresonys]

Re: KDL-43W805C - backlight and sound work but no picture

Only thing you did different was the update, maybe that did the trick or you had a bad or dirty connection that got corrected??

[Dobsuk]

Re: KDL-43W805C - backlight and sound work but no picture

the voltage measurement needs to be done when it is working and then again when it stops.

Yeah i know, sorry. I took them now and they are the same...

AVDD: 15.66V
VSS: -7.09V
VCOM: 6.47V
VCOM_CF: 6.47V
VGHD: 0V

Shall i take them with disconnected ribbon cables?

Only thing you did different was the update, maybe that did the trick or you had a bad or dirty connection that got corrected??

No, the update did not fix it. I am still troubleshooting it. It is working at this morning. May be it is something about the connections to the panel. I have no idea. But as i said i noticed that when i do not have normal pictures the bottom edge, where the connections to the panels are, was getting warm. And not now - when i've go normal and clear picture.

[budwich]

Re: KDL-43W805C - backlight and sound work but no picture

It appears that is isn't related to those voltages (not that I know a lot about what they represent... just looking for things that don't ring right like "0" or high, etc)

When you say that when things go wrong, the "panel connection gets warm", can you post a picture of the area? Another idea is that in my travels, I have come across "stories" about issues with the edge boards / panel touching frame members at spots due to assembly issues which causes problems. This might be a possibility since you seems to have found that orientation helps in some form.

[Dobsuk]

Re: KDL-43W805C - backlight and sound work but no picture

Yeah mate. I will disassemble everything to make sure that everything has been checked. Just fell off with my bike today and i will take some rest now. I will upload photos for sure once i find time.

[Dobsuk]

Re: KDL-43W805C - backlight and sound work but no picture

But i think definitely is something about the bottom boards. The tv is working all day long today and sometime the bottom edge panel is getting warm sometime is cold

[Dobsuk]

Re: KDL-43W805C - backlight and sound work but no picture

Ok. I found some time today to finish with disassembling of this tv even it still works... Anyway, it looks it will be easier to disassemble some space ship rather than this tv. I could not find and any tutorial or video how to disassemble it to the screen. And I prefferd to do not take that risk to damage something more in case it is working now. I tried to move the bottom bezel a bit but nothing changed with the picture. So i am really interested what was wrong with this tv and i am watching it now. So next time when it start to show the same symphtoms again i will try to reach the end.

[Dobsuk]

Re: KDL-43W805C - backlight and sound work but no picture

Hi, guys. I am back in the game with this tv It was working in the last months but now the problem came again. This time the tv is set so i can change the channels, play youtube etc. So, the tv starts with white screen every time. Then if i have something on the background the colored lanes are coming in few minutes.

If there is no moving picture on the background nothing is happen - just white screen. And after these colored lines the picture is coming normal in another few minutes.
In the last few days after the white screen and then the colored lines when the picture comes it is with big distortions:

Can i believe it is something about the TCON board or?!?