Repair for TDS210

[Orion63]

Hi, I have had this TEK TDS210 scope for a few years and did not happen to use it for a long time. When I switched it on a few days ago, although I can see faintly that all the functions working on the screen, but the screen itself looks to be fuzzy with some crack like appearance on it from inside. Please refer to the attached pictures. I guess, some issue with the Front Polarizer. Anyone in the forum have any experience in replacing the Polariser ?
Other questions I had was :
1. Whether only the front Polarizer needs to be changed ?
2. What Polarizer is required 0 deg or 90 deg or any other ?
3. Whether the Backlight also needs to be changed ?

Regards

[shakalnokturn]

Yes it looks like the front polariser, I've done it before in a TDS 220, unfortunately the polariser I tried was not the right one and gave a low contrast although usable.

If I was to try again today I'd test this one:
https://3dlens.com/linear-polarizer-film-200x250mm-with-adhesive.php
Don't be too disappointed if you test it and it's not great.

Removing the polariser isn't fun, heat and white spirit do help to peel the glue.

CCFL looks OK.

[george.b]

Hi,

Anyone in the forum have any experience in replacing the Polariser ?

Yes, I have replaced the polarizers on my TDS220 and helped a friend replace the polarizers on his TDS210. Dunno if you've done this before: it's a pain in the ass to do, it stinks, and you have to clean the adhesive residue from the screen. Nail polish remover and an old credit card help a little. Be very careful not to break the screen, nor to rip the flex cable.

1. Whether only the front Polarizer needs to be changed ?

Probably not. It seems both polarizers degrade.

2. What Polarizer is required 0 deg or 90 deg or any other ?

My friend bought new 0/90 degree sheets and the result was pretty good. I used old polarizer from a broken LCD monitor and I just rotated the sheets until I was happy. Ended up with a yellowish tint, I'll probably re-do it one of these days.

3. Whether the Backlight also needs to be changed ?

No, unless you find it's too dim for some reason. Mine was. Instead of replacing the CCFL, I cobbled an LED backlight together.

[Orion63]

Thanks, for the replies. Anyways, I will try replacing the polarizers first before I buy a new China-Make LCD. I saw a few in the aliexpress. Any recommendations for LCD purchase which has been tested working ?

[george.b]

Thanks, for the replies. Anyways, I will try replacing the polarizers first before I buy a new China-Make LCD. I saw a few in the aliexpress. Any recommendations for LCD purchase which has been tested working ?

What I can say is that the later model, made by Nan Ya, seems to look quite better (to me, at least) than the older one made by Sharp.

[Orion63]

Hi, @george.b and @shakalnokturn, I have taken apart the LCD Display module out from the TDS210 body. May I know which is the Polarizer? Is it the entire thick film (about 0.5~0.7mm) above the glass or is there another film above this thick film ?
Please refer to the pictures attached. Regards

[george.b]

The polarizer film is the entire outermost layer. It's about the same thickness as an overhead projector transparency. The surface you're left with for replacing the polarizer should be bare, clean glass.
You'll probably have to do this to both sides of the LCD panel.

[Orion63]

Thanks for the reply @george.b. It is a little thicker than the OHP transparency sheet, that's why I was a bit reluctant to pull it out. Secondly, I saw there was a small bubble at the centre of the screen (with the old polarizer still on it). When I touched this bubble, got some liquid on my fingers with the smell of Nail Paint. Does it imply the LCD screen crack and the pneumatic LCD liquid spill out ? Regards.

[george.b]

It's probably moisture and old polarizer goo. Like I said before, dead polarizers stink
The LC fluid is sandwiched between the glass sheets, which are rather thick. See attached pic. Liquid crystal doesn't smell particularly pungent IMO.

[shakalnokturn]

I didn't need to replace the back polariser on mine.
Maybe I should have done to adapt to the new front one but the original back one hadn't degraded so I left it alone.

[Orion63]

Thank you, @george.b and @shakalnokturn for your valuable inputs. I managed to pull out the Polarizer from the front surface successfully. It took quite a work to pull out the film and clean up the residual glue from the glass  . Luckily no cracks on the glass. Yes, as mentioned by George.B, I will have to replace the Polarizer from the back end too as it is also seen to be cracked. Will post the update.

[Orion63]

Mission Accomplished 
Today received the Polariser. Repalced both the front and the back polarisers and Voila !!!!! The results were amazing. Please see the attached Before and After pictures.
Thank you @george.b and @shakalnokturn for your support and timely help.
In the entire process, the residual glue cleaning was the most time consuming. Took almost 1 hour per side for the clean up. Used Nail Polish remover to soften the glue. Then scrap off using a sharp razor blade. Clean up the glass with IPA.

[george.b]

Well done!
Always nice to see these scopes get a new lease on life

In the entire process, the residual glue cleaning was the most time consuming. Took almost 1 hour per side for the clean up. Used Nail Polish remover to soften the glue. Then scrap off using a sharp razor blade. Clean up the glass with IPA.

Yep, that's pretty much how it went for me, too. Would be nice if there was a more efficient (yet safe) solvent.

[CharlieD]

Mission Accomplished 
Today received the Polariser. Repalced both the front and the back polarisers and Voila !!!!! The results were amazing. Please see the attached Before and After pictures.
Thank you @george.b and @shakalnokturn for your support and timely help.
In the entire process, the residual glue cleaning was the most time consuming. Took almost 1 hour per side for the clean up. Used Nail Polish remover to soften the glue. Then scrap off using a sharp razor blade. Clean up the glass with IPA.

Nice Work

What polarizer film you used? Was the one provided by shakalnokturn in the link of the reply #1, or another?

I'm going to try the same with a TDS220 and want to be sure to order the right one.

Thanks in advance.

[shakalnokturn]

If you look at the reviews on the 3DLens product page one is:

"Repaired a Tektronix TDS210 display
Mike - California, USA -
Worked, a bit lighter than original. I may try two layers on each side."

[CharlieD]

If you look at the reviews on the 3DLens product page one is:

"Repaired a Tektronix TDS210 display
Mike - California, USA -
Worked, a bit lighter than original. I may try two layers on each side."

Thanks.

I have noticed in some forum posts, and in several YouTube tutorials, that almost always when changing the polarizing filter on an oscilloscope or test equipment, the screen acquires a yellow/orange color, I would like to investigate more about this and How can it be amended?