Thorn 65thl4kst1

[viewerau]

Re: Thorn 65thl4kst1

Ok, I used a number of ways.

Plug out, nothing connected 0/0
Plug in,tv on standby 031/031
Plug in, pressed power on remote 1997/1997...this slightly fluctuated down and back up between 1958 and 1997 on both sides
EDIT
I have checked all ribbon cables to make sure they are seated correctly. Touching or wiggling them does not make any difference, still just the white screen.

[dick_barton]

Re: Thorn 65thl4kst1

If you are on the 20 Volt dc range then the maximum reading will be 19.99V and minimun would be 0.01V so I don't understand where the 1958 is coming from unless you mean it's 19.58V and 19.97V?

[viewerau]

Re: Thorn 65thl4kst1

This is the numbers that my digital readout show.

It does not indicate any decimal point .

It is set on the 20 position

Perhaps, as my Meter is very old, that is the reason?

[viewerau]

Re: Thorn 65thl4kst1

The 1957/1958 etc is a number that will not completely settle whilst I hold the red probe on each end of the fuse. It does not ever sit on one number.

I assume it is saying 19. something volts?

[dick_barton]

Re: Thorn 65thl4kst1

At this point I do not trust your multimeter so first can you check any 9V batteries you may have and see what it reads otherwise I would try another multimeter.

[viewerau]

Re: Thorn 65thl4kst1

Thanks for the continued help...I will get another multimeter tomorrow.

[dick_barton]

Re: Thorn 65thl4kst1

At this point I do not trust your multimeter so first can you check any 9V batteries you may have and see what it reads otherwise I would try another multimeter.

Or put new batteries in the one you have and then check any 9V battery you have to hand.

[viewerau]

Re: Thorn 65thl4kst1

Sorry, I am back again.....

I purchased a brand new multimeter..

Nothing plugged in, no power no nothing 0/0
Power plug in, set on standby 0.06/0.06
Power plug in, click power on remote, both sides 12.07/12.07

Can this help us better....

[viewerau]

Re: Thorn 65thl4kst1

OK....I have just noted something after taking a close up photo of my led driver board on this telly, blowing it up to look at on my pc, and comparing it with one for sale online.

The image on the left is a board for sale on the net. The image on the right is my board.

Could it be work has been done on this led driver board on mine, by the look of all the solder and the caps sitting on an angle etc?

Is there a method I can use with my meter to put it on a setting and seeing if it is behaving correctly.

Or am I off target as usual?

Thank you again.

edit...

I found another clean picture of a same board for comparison...thanks

[dick_barton]

Re: Thorn 65thl4kst1

The picture of your board is too dark to make a good comparison although the amount of flux around the capacitor on your board does appear to suggest it has had some work done on it.
The 12V on the Tcon both sides is fine confirming that you have power to the tcon board.

[viewerau]

Re: Thorn 65thl4kst1

Enlarged photo

[dick_barton]

Re: Thorn 65thl4kst1

Post #1 Initially you say that the service engineer said it was a faulty mainboard and you were looking for advice on a replacement mainboard.

In post #15 you mention that you have put a replacement mainboard in and also say the Tcon board has extra letters...... So have you changed the original Tcon?
The pictures are too dark to be able to compare them. "TV powers to on, but the screen is just white...grrrr" so the backlights are working.

Post# 28 You confirm that you have sound

Post #48 Finally confirm that the Tcon has a 12V supply at both ends of the fuse.

Post #49 You mention there may have been some work on your led driver board. But if you have a white screen then the backlight led driver board is working.

Could you pictures of the original / replacement tcon and original mainboard / replacement mainboard as bright and clear so as to read any text on them.

[viewerau]

Re: Thorn 65thl4kst1

Original Mainboard replaced from a working exact same model Thorn tv, via ebay seller...all numbers match

The T-con board in this tv is the original one...never removed since it has been here...only ribbon connections and power on fuse checked.

White screen still glows when telly turned on.

I don't know what to do now...

EDIT
Again dark now, so will photo both the original mainboard as well as the one purchased, tomorrow, in better light.

[viewerau]

Re: Thorn 65thl4kst1

Original Board photos

[viewerau]

Re: Thorn 65thl4kst1

Replacement and now fitted board

[viewerau]

Re: Thorn 65thl4kst1

Sorry, forgot to add the photo of my t-con

[dick_barton]

Re: Thorn 65thl4kst1

The main boards do look identical.
There are a number of test points on the Tcon but they are difficult to make out from the photos.
The ones I can see are HVDD, VGL2 & VCC18. Can you measure the voltages at those points to start with.

[viewerau]

Re: Thorn 65thl4kst1

Thanks again,

I will test these again in the morning.

Do I put the meter on 20 again and negative to chassis?

[dick_barton]

Re: Thorn 65thl4kst1

Yes, That's fine. Keep an eye out for the "-" sign on your meter indicating a negative voltage.

[viewerau]

Re: Thorn 65thl4kst1

HVDD...reads 0.00 to -0.01
VGL2....reads 0.13 to 0.15
VCC18..reads 0.00 to -0.01

meter set on 20, negative to chassis, positive to check point. Panel powered to on.