Thorn 65thl4kst1

[dick_barton]

Re: Thorn 65thl4kst1

So if your meter was set to 20 volts DC and the red lead taking the reading and black on chassis then those readings are not good.

With the set powered up you said you have 12V dc on both sides of the Tcon fuse.

From your readings VCC18 should read 1.8V DC

There are several other test points I've circled in blue and they are the ones I can see. The legend is extremely small and hard to read from the image above.

[viewerau]

Re: Thorn 65thl4kst1

Thanks dick...
I thought that you'd say they are not good.

I had to really try hard to get the readings, as the picture (even though you say is hard to read), is a lot better that actually trying to get the tip of the probe on those spots. A very good head magnifying glass would be great!!

Is your thoughts so far, that it could be the T-con?

I will try those other points tomorrow in the daylight, as it is much easier than night time. I'm sure there may be more points, but I guess the only way to do that would be using a magnifying glass, and then maybe telling you where they were, and what it says they are. Other than that, I could try photograph the whole lot in sections, close up, and sort of stitch them together, if necessary?

Thanks dick...again, all help is great...cheers.

[dick_barton]

Re: Thorn 65thl4kst1

Most phone camera's are pretty good and taken in daylight should make reading the labels much easier.

[viewerau]

Re: Thorn 65thl4kst1

ok...will photograph again tomorrow

EDIT...from looking at some photos blown up on my pc, I think the red spots are the total test points on board?

To me, forgive me if I am wrong, test points appear to be only round dots? I take it other shaped one's mean something different..eg the one you marked blue on the left VDO seems a different shape

Should I measure all these?

[viewerau]

Re: Thorn 65thl4kst1

I hope that these are suitable?

[viewerau]

Re: Thorn 65thl4kst1

The voltage readings as requested

[dick_barton]

Re: Thorn 65thl4kst1

It appears that other than the input voltage (12V) being present on the board it looks like all the other voltages needed are not present.

If you disconnect the ribbons from the tcon to the panel (flip upwards the black bar) and remove the ribbon carefully then power up and check if the voltages on the tcon have changed. Perhaps the panel strip board is pulling down the Tcon voltages.

When you re-insert the ribbon cables (set powered off) do so carefully so as not to damage the gold contacts at the end of the ribbon which can be very easily damaged.

Other than that all I can suggest is to try another Tcon if inexpensive.

[viewerau]

Re: Thorn 65thl4kst1

When you re-insert the ribbon cables (set powered off) do so carefully so as not to damage the gold contacts at the end of the ribbon which can be very easily damaged.

Other than that all I can suggest is to try another Tcon if inexpensive.

Thanks again.

I know something definitely different does happen when the ribbons are removed, as earlier on, removing one ribbon made no change, but reinserting that one and then disconnecting the other one resulted in the bright white illumination on one side of the screen, and brilliant dark black on the other half.

To date, I haven't seen anyone comment as to why that happens, and whether it points to something significant? When I see other images like that, and they mainly seem to refer to Sony and other models, and not this brand, most comments seem to indicate something to do with the t-con.

Does anyone have any thoughts on the black and white halves, or is this insignificant?

I will measure those voltages again with the ribbons disconnected asap.

Thank you dick.

[dick_barton]

Re: Thorn 65thl4kst1

Removing the left then right ribbon is to try and identify which side of the panel may be faulty, ie may be showing vertical lines.
Unfortunately you have no image because the tcon voltages are missing so will not display an image on the panel.

[viewerau]

Re: Thorn 65thl4kst1

Unfortunately you have no image because the tcon voltages are missing so will not display an image on the panel.

Thanks for explaining that ...cheers

[viewerau]

Re: Thorn 65thl4kst1

Just harping back to the led driver board, here is a photo (same one as mine) of what one looks like.

Can I just test the voltages it shows the 24v test areas by simply putting the negative probe to chassis and the positive to the adjacent pin?

Do I still set my meter to 20?

Thanks

[dick_barton]

Re: Thorn 65thl4kst1

The voltage written says 24V so you need to move the meter dial to the next range up ie 200V
But you say your backlights are working so I cannot see what your problem with it would be?

[viewerau]

Re: Thorn 65thl4kst1

Thanks....I just thought that as it is described as a led driver board, that maybe that one might have some bearing somehow. As you can see, willing to check anything if it helps.

Cheers

[viewerau]

Re: Thorn 65thl4kst1

Some more measurements

Board connected normally, all ribbons connected,vc2 was 0.13-0.15
Same again, left ribbon disconnected, vc2 was 6.97
Connected left ribbon, disconnect right, vc2 was 0.14


Board connected normally, all ribbons connected,vc18 was 0.00
Same again, left ribbon disconnected, vc18 was 1.79
Connected left ribbon, disconnect right, vc18 was 0.12


Board connected normally, all ribbons connected, vcc was 0.60
Same again, left ribbon disconnected, vcc was 3.26
Connected left ribbon, disconnect right, vcc was 0.60

I then tested the led driver board, and all 24v pins measured correct at 24v

EDIT
When the two ribbons from the tcon board to the panel are connected...white screen backlights, nothing shown on screen, no lines, no sight of movement, etc
When the right ribbon only is disconnected....white screen backlights, , nothing shown on screen, no lines, no sight of movement, etc
Right ribbon reconnected and left ribbon disconnected...left half off panel vivid white, right half of panel jet black, no lines, no sight of movement, etc

[dick_barton]

Re: Thorn 65thl4kst1

So it appears as though with the left ribbon disconnected several supplies are there.
VCC18 reads 1.7V which is close to what it should be of 1.8V

I'm not 100% certain but I think your problem is with the left side circuitry of the panel circuit board. With the left ribbon disconnected you appear to be getting voltages at the test points although what they shoud be, I don't know but they shouldnt be zero as when the left ribbon is reconnected.

When you were testing did you have a signal input and could hear the sound?

Do the panel ribbon cables feed to the tcon from the top of the tv or from the bottom? Can you post a photo of the back of the set .

At this point I feel that other forum members opinions would be welcome.

[viewerau]

Re: Thorn 65thl4kst1

Hi...
Some shocking pictures here, but I hope good enough for now? Sorry, dark again here..

During testing once, I connected a dvd player via component inputs, and kept pressing the input button on remote until I snagged the right input, and yes, sound was there on that dvd, but no video.

Yes, would love more readers thoughts, but highly appreciate your efforts...FANTASTIC !!

EDIT
the panel ribbon cables feed to the tcon from the bottom of the tv .

I have wriggled those connectors too, but no change to the picture.

I was now thinking that perhaps I will need to try to remove some extras at the bezel, bottom end stuff, to see if I can expose the connections that go down to the panel, and see if something is evident there? What do you think?

[dick_barton]

Re: Thorn 65thl4kst1

It looks like the panel circuit is at the bottom of the set. My thoughts at the moment is , has there been water ingress when cleaning the screen that has damaged this board.

[viewerau]

Re: Thorn 65thl4kst1

The people just said it stopped working. They are a couple in their 30's and didn't look the type that would fib. I can only but trust their story.

It is half past midnight here, so bed time for me again...this time differential between us makes this thread long hey...cannot be helped though.

I hope you are enjoying the coming warmer weather...and go Liverpool...over n out for now.

[dick_barton]

Re: Thorn 65thl4kst1

During testing once, I connected a dvd player via component inputs, and kept pressing the input button on remote until I snagged the right input, and yes, sound was there on that dvd, but no video.

Repeat that test once more but this time with the left ribbon cable disconnected and see if you get hallf a picture.

[viewerau]

Re: Thorn 65thl4kst1

Hi...connected an android tv device via hdmi...same results, audio, no picture.

Removed the left ribbon, still no result