What size and angle for a PowerBook 145B screen polarizer?

[MrGasS27]

Hi everybody.

My hateful PowerBook 145B developed the infamous vinegar syndrome and I'm in the process of removing the second sticky sheet of the polarizer.
Right now I trashed everything into a box due to my poor spare time and to the strong smell of the polarizer that was literally killing me (and also because I really hate this PowerBook).

So, can I ask you what size and angle should the new polarizer have?

As I don't want to kill my working Macs, I use this PowerBook to test SCSI devices that I make and, as I need to test the 2.5" SCSI header on my own through-hole RaSCSI prototype board, I would like to repair this piece of trash as soon as possible.

Thank you all!

 

[MrGasS27]

Did someone discovered what's the correct angle for this screen?

The plastic casing is completely destroyed now because of age, but I would like a lot to stuff this powerbook in a clear plastic suitcase to use it as a sort of "portable" desktop Mac.

Thank you.

 

[desertrout]

I also would like to know... if you find out, please update us!

 

[alexGS]

It doesn’t actually matter if you are replacing both the front and rear polarisers, which I think you are - with the screen in that condition. The brown blotch comes from the rear polariser in my experience.

The angle is 45 degrees originally, but I’ve used 90-degree film on the front and rear. All that matters is the 90-degree angle difference between front and rear. I had to cut my rear sheet ‘sideways’ but I think if you have 45-degree film, you use it upside down.

There are some bigger problems with the contrast of the display affected by the quality of the replacement film. If two pieces held at 90 degrees to each other don’t block out the light well (ie. appear a deep, dark black) then you’re in for a poor-contrast, washed-out result. It is usable, however. In the photos below, the last photo is what it should look like (that’s a good display) while the second-to-last shows the result of replacing the film with the film that I used (cheap from AliExpress).

Here is a link to good film that someone else has used (I have not tested this film yet):

https://a.aliexpress.com/_mKesOaC

It’s about twice the price of the film I used. Get what you pay for

Note that I’ve been working on a Powerbook 100 but it is a mono display that I believe works the same as the 145B’s. The 150’s greyscale LCD was a different story; see my next post

 

[alexGS]

Here is a similar process on the Powerbook 150 which I did not succeed with. The replacement film introduced sepia colours - purple/blue/yellow instead of black/grey/white - and it seems I also broke the ribbon connections in handling which gave a strange shifted effect to the display.

Anyone else reading this, please learn from my mistake and on greyscale Powerbooks, I suggest not to attempt the film replacement unless you have a known-good replacement. It’s something about a ‘retarder layer’ being necessary and I’d like to know where suitable film for greyscale LCDs can be found. (The film I linked above is suitable for a mono or colour display).

 

[MrGasS27]

It doesn’t actually matter if you are replacing both the front and rear polarisers, which I think you are - with the screen in that condition. The brown blotch comes from the rear polariser in my experience.

The angle is 45 degrees originally, but I’ve used 90-degree film on the front and rear. All that matters is the 90-degree angle difference between front and rear. I had to cut my rear sheet ‘sideways’ but I think if you have 45-degree film, you use it upside down.

There are some bigger problems with the contrast of the display affected by the quality of the replacement film. If two pieces held at 90 degrees to each other don’t block out the light well (ie. appear a deep, dark black) then you’re in for a poor-contrast, washed-out result. It is usable, however. In the photos below, the last photo is what it should look like (that’s a good display) while the second-to-last shows the result of replacing the film with the film that I used (cheap from AliExpress).

Here is a link to good film that someone else has used (I have not tested this film yet):

https://a.aliexpress.com/_mKesOaC

It’s about twice the price of the film I used. Get what you pay for

Note that I’ve been working on a Powerbook 100 but it is a mono display that I believe works the same as the 145B’s. The 150’s greyscale LCD was a different story; see my next post

Thank you a lot for your precious replies.

Oh, so, there's another polarizer filter on the back? Sounds like I'll give up on it lol
I stored the screen in summer 2022 and never completed the job due to health issues I had at the time, it's half scraped and meanwhile the plastic lid got worse: as far as I remember, hinges smashed the upper assembly.

Yesterday night I read of a user who's trying to translate the LCD signals with a Pi Pico, which sounds like an amazing idea.
I would rather convert this system into a desktop than waste money and time on polarizers and smashed plastic pieces, I bought this PowerBook in 2016 for 5 euros and it was already in an ultra-bad shape.
As the 145's motherboard is really small, the idea of a small Macintosh never left my mind: with USB-PD power, VGA or HDMI video output and BlueSCSI for storage would be beautiful.

I still need to do a thing: virtualize a PowerView with the RaSCSI/PiSCSI in order to get video via SCSI from the PowerBook, I'll try to work on this in a month.

 

[desertrout]

It doesn’t actually matter if you are replacing both the front and rear polarisers, which I think you are - with the screen in that condition. The brown blotch comes from the rear polariser in my experience...

Wow, this is impressive, adventurous stuff. Thanks for leading the charge and sharing your experience. More research to be done...

 

[alexGS]

Wow, this is impressive, adventurous stuff. Thanks for leading the charge and sharing your experience. More research to be done...

Cheers. I am not an expert in this, as I am yet to find the best replacement film to use. The link I posted to matt film seems promising; glossy film is not forgiving at all and scratches easily (see below).

I was reasonably successful on a PC laptop with TFT screen, where I replaced the front and rear films. Note the similar brown blotch (visible when holding replacement film over the front), which is caused by a breakdown of the rear film. I think this would apply equally to a Powerbook G3 from the same era.

The photos are a bit out of order but you can see the state of it when I started, and the difficulty in removing the adhesive (which is where all the breakdown seems to happen).

Admittedly I ruined the before-and-after photos by replacing Windows XP with 98 You can see a couple of small air bubbles in the desktop background and some scratches caused by the side-to-side motion of a cloth used to apply the film. Perfection cannot really be expected, unfortunately!

 

[alexGS]

Oh, so, there's another polarizer filter on the back?

Yes. The angle of the film must be opposite the angle of the front film, ie. to achieve a black-out condition when the LCD is off.

Because the film is stuck to the other side, it is effectively ‘flipped over’. You can get 135-degree film to oppose the 45 but I haven’t needed it, I think if you get a large enough piece, you can rotate 90 degrees before cutting anyway.

If you ever use the Powerbook while wearing polarised sunglasses, then you would have to position both front and rear films at the correct angles to see anything at all, which is probably why they chose the angles they did otherwise it doesn’t matter whether the films are 45, 90, 0, etc. as long as the difference between front and rear is 90.

I would rather convert this system into a desktop than waste money and time on polarizers and smashed plastic pieces, I bought this PowerBook in 2016 for 5 euros and it was already in an ultra-bad shape.
As the 145's motherboard is really small, the idea of a small Macintosh never left my mind: with USB-PD power, VGA or HDMI video output and BlueSCSI for storage would be beautiful.

I still need to do a thing: virtualize a PowerView with the RaSCSI/PiSCSI in order to get video via SCSI from the PowerBook, I'll try to work on this in a month.

Fair enough. I’d rather just fix what’s there than deal with the technical challenges in replacing an LCD with video-out There are 3D-printable fixes for the hinge mountings.

 

[MrGasS27]

Yes. The angle of the film must be opposite the angle of the front film, ie. to achieve a black-out condition when the LCD is off.

Thank you for these tips, I really appreciate them.

Fair enough. I’d rather just fix what’s there than deal with the technical challenges in replacing an LCD with video-out There are 3D-printable fixes for the hinge mountings.

Unfortunately I never used a 3D printed, nor I have access to one, that's why because I wanted to stuff the entire computer (maybe ditching the floppy drive, the keyboard and the trackpad) into a clear utility briefcase, but you know, I might change idea in future.

Anyway, the infos you gave me are really useful for a future restoration and for the entire community, maybe I could do the job cutting a 32" polarizer film in future, we'll see.

Oh, I forgot I should replace the polarizer also on my Pismo from March 2001

Thank you again (love that Gateway)

 

[alexGS]

Thank you again (love that Gateway)

Cheers. Hey, I thought it was risky posting pics of a Windows machine here… but I did it for the simple reason that it’s a similar 14.1” TFT to the G3 PowerBooks (and I haven’t done one of those yet) Glad this group has the maturity to see through the situation!

 

[3lectr1cPPC]

Nice Gateway indeed
One of those is definitely “the list” for me.

 

[alexGS]

Nice Gateway indeed
One of those is definitely “the list” for me.

Lol - it did have better speakers than everything else, and a swappable floppy/CD drive. It was a Japanese-made laptop, so close-fitting and solid with lots of metal bits and a myriad of different-length screws. Worst part was the 3x NiCd cells for CMOS/parameter RAM; they leaked. I had to repair the connections for the replacement battery.

Just a means to an end for me, I sold it, as I have a Compaq Evo n620c for Windows 98 duties. My ultimate goal is a Powerbook 540c and I’m nearly there… only need an LCD panel for it. I used all the casing parts from an as-new 520c to replace the smashed parts of the 540c. So for now, I have a 540c with 520c display

 

[techknight]

I wonder if there is a chemical process to dissolve the remnant adhesive on the glass. because the razor method seems like a pain in the ass and can go incredibly wrong if you slip and hit a ribbon.

 

[alexGS]

I wonder if there is a chemical process to dissolve the remnant adhesive on the glass. because the razor method seems like a pain in the ass and can go incredibly wrong if you slip and hit a ribbon.

I certainly tried every solvent I could think of, including brake cleaner and paint thinners. Only alcohol worked (either methylated spirits or isopropyl alcohol), softening it a bit so a blade could remove it.

The ribbons get damaged more from the height difference between the LCD and the thin circuit boards (bending occurs). For the last one I did, I worked on a piece of corrugated cardboard to try and match the heights.

 

[techknight]

Here is a similar process on the Powerbook 150 which I did not succeed with. The replacement film introduced sepia colours - purple/blue/yellow instead of black/grey/white - and it seems I also broke the ribbon connections in handling which gave a strange shifted effect to the display.

Anyone else reading this, please learn from my mistake and on greyscale Powerbooks, I suggest not to attempt the film replacement unless you have a known-good replacement. It’s something about a ‘retarder layer’ being necessary and I’d like to know where suitable film for greyscale LCDs can be found. (The film I linked above is suitable for a mono or colour display).

That has to reeeeeeeeeally smell bad. I peeled a polarizing film off of a 2300c display and man... putrid.

 

[3lectr1cPPC]

I feel lucky for having never had this happen to me yet...I really hope that my luck holds.

 

[MrGasS27]

That has to reeeeeeeeeally smell bad. I peeled a polarizing film off of a 2300c display and man... putrid.

Aside from my health issues, I stored my screen without finishing the job because I was about to die, that stuff was nasty

 

[alexGS]

That has to reeeeeeeeeally smell bad. I peeled a polarizing film off of a 2300c display and man... putrid.

Yup - but it’s just a vinegar smell, acetic acid released when the adhesive layer breaks down

I don’t like vinaigrette salad dressing but if you do, I imagine it must smell delicious