Tektronics THS720 scope display issues...

John Robertson

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Mar 27, 2021, 1:35:46 AM3/27/21

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A friend of mine in AU just asked me about

"Tektronix THS720 handheld digital oscilloscope. As you can see in the
attached photo, the LCD module is starting to go bad. Research indicates
that the problem is likely due to the polarizer films deteriorating, and
they can be replaced"

Anyone have any other suggestions? The image in the photo showed a clear
image, just fading on part of it. I suggested the inverter be checked,
but am no expert on these units.

Thanks!

John :-#)#

ohg...@gmail.com

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Mar 27, 2021, 10:44:53 AM3/27/21

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Any way to post a pic John? I have that model and would be interested in seeing the issue.

John Robertson

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Mar 27, 2021, 12:27:09 PM3/27/21

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Yes, of course - here is a link to the image he sent me.

https://www.flippers.com/images/delete/Tektronix_THS270.JPG

I'm sure he will appreciate any advice, he replied to me:

"Yes the display is illuminated by a small Cold Cathode Fluorescent Lamp
which is working normally. The problem is that the centre area of the
display is going darker and darker while the perimeter is still OK.

I'll keep looking for info about polarizer film...."

Thanks!

John :-#)#

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Three Jeeps

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Mar 27, 2021, 12:46:53 PM3/27/21

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On Saturday, March 27, 2021 at 1:35:46 AM UTC-4, John Robertson wrote:

There is a tekscopes forum that I hang out in that can be very helpful.
https://groups.io/g/TekScopes/
Suggest you post there as well.
Good luck
J

ohg...@gmail.com

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Mar 27, 2021, 2:35:07 PM3/27/21

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On Saturday, March 27, 2021 at 12:27:09 PM UTC-4, John Robertson wrote:
> On 2021/03/27 7:44 a.m., ohg...@gmail.com wrote:
> > On Saturday, March 27, 2021 at 1:35:46 AM UTC-4, John Robertson wrote:
> >> A friend of mine in AU just asked me about
> >>
> >> "Tektronix THS720 handheld digital oscilloscope. As you can see in the
> >> attached photo, the LCD module is starting to go bad. Research indicates
> >> that the problem is likely due to the polarizer films deteriorating, and
> >> they can be replaced"
> >>
> >> Anyone have any other suggestions? The image in the photo showed a clear
> >> image, just fading on part of it. I suggested the inverter be checked,
> >> but am no expert on these units.
> >>
> >> Thanks!
> >>
> >> John :-#)#
> >
> > Any way to post a pic John? I have that model and would be interested in seeing the issue.
> >
> Yes, of course - here is a link to the image he sent me.
>
> https://www.flippers.com/images/delete/Tektronix_THS270.JPG
>
> I'm sure he will appreciate any advice, he replied to me:
>
> "Yes the display is illuminated by a small Cold Cathode Fluorescent Lamp
> which is working normally. The problem is that the centre area of the
> display is going darker and darker while the perimeter is still OK.
>
> I'll keep looking for info about polarizer film...."
>
> Thanks!
>
> John :-#)#
>
> --

I have the serv manual if he ever needs anything scanned from it. In the meantime, he can always pick up a small scrapped LCD TV. Thes use external polarizer sheets that can be cut to fit.