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We've got a problem... ...and a solution! (PB1XX permanent brittle plastics / screen hinge fix)

PB170

Well-known member
The problem…

The problem 2.jpg

The problem 1.jpg

The problem 3.jpg


A bit of background/history:

Almost immediately after I purchased my PowerBook 170 back in 2001, two unfortunate accidents happened.

After only using it once or twice, a crack in the insulation at the tip of the AC plug (a problem affecting the first version of PB1XX adapters) caused the fuse to blow on the motherboard, resulting in a repair at a local Apple reseller and the purchase of a new, second hand power adapter, which in total cost me more than I had just spent on the computer.

Then, shortly after I had the computer up and running again, I decided to try and see if I could remove a small, annoying hair that was stuck somewhere between the layers in the middle of the display. After carefully removing the front bezel, I made the devastating mistake of trying to adjust the display slightly, resulting in two of the screw posts breaking completely free from the back.

Some time later, I decided to try to fix the problem by drilling four small holes through the rear part of the display housing* and running new screws and bolts through it to secure the display to the hinge, covering the bolts with the same type of rubber covers used over the screws on the front to retain the original look. This slight modification turned out very successful, and has held together well through more or less daily use for two decades all up to the present. Considering how some of the screw posts inside the machine fall apart more or less on their own, I'm amazed that the plastics has held together for this long.

An old photo of the fix:

Fix.jpg


However, recently, things started to change…

Small cracks in the plastics began to appear in 2020. Back then, I repaired them with JB Weld, which has held together well. (Thanks by the way for recommending this amazing product – incredibly strong, not to mention it matches the color of the PowerBooks perfectly!) However, during the past few months, new, more severe cracks started to appear (in new places), and at this point many of them were pretty much beyond repair if the plastics were also going to support the hinge screws like before**. So I needed a more future proof solution.

After a lot of thinking, considerations, and careful measurements, I settled on a metal extension design for the hinges to completely free the display housing from the hinges and instead secure the rear part of the housing at the top of the display where the stress is much lower:

Extension.png

One consideration in the design was to avoid having the metal extensions go over any components on the display PCB, to avoid the risk of damage to the PCB in the future. That meant that they would have to follow the sides of the PCB. This, however, would mean that the stress on the extensions would be focused on the narrow, horizontal part near the hinges. To prevent the metal from twisting during use, I designed the extensions out of 1.2 mm steel, which seemed to be the sweet spot (1.0 mm steel seemed a bit too weak, and pure iron which I first considered was much too soft). I also made the vertical parts much wider than I originally had planned in order to minimize the length of horizontal part. The pieces weigh in at 44 g each, so quite acceptable, although a bit more than I first had in mind.

The height of the extensions means the display will move 1.2 mm closer to the bezel (which is actually very nice since there's quite a bit of room in the original design and it's nice with a closer fit). To make the display sit flat, I added two washers between the display and the two lower screw post (not pictured).


Finished extensions:

Finised extensions.jpg

(Bonus point that they kind of look like giraffes or dinosaurs :giggle:)


Some photos of the work in progress:

Work in progress 1.jpg

Work in progress 2.jpg

Work in progress 3.jpg

Work in progress 4.jpg


Somewhat surprisingly, the tolerances between the hinges and the display housing are quite precise, so despite careful measurements, I had to extend/elongate the top screw holes slightly to allow for some fine tuning of the position of the rear plastic part.

Aside from this minor adjustment, the design turned out successful, and I now have a solution where the plastic housing is completely separate from the hinges, and the display is held up entirely by the extensions rather than the plastic housing! :D :D

Such an incredible and relieving feeling to finally not have to worry about over- or under-tightening the screws, and instead secure them tightly entirely around metal parts!


Final assembly:

Final assembly 1.jpg


Details of the bent parts:

Detail 1.jpg

Detail 3.jpg

Detail 2.jpg


I include the final, revised design in Adobe Illustrator 9 format here if anyone is interested.

A few notes:
  • The current design of the extensions will only work with the PowerBook 170 display (and maybe other active matrix displays in the series). It will have to be modified to work with passive matrix PowerBooks.
  • The design requires the complete removal of the screw posts on the rear part of the housing and the protruding parts around the screw holes on the inside of the front bezel, as well the addition of metal plates to the front bezel to be able to secure the new screws to hold the bezel in place (not needed for the hinge extension to work, but the bezel will stand out a bit around the hinges without them). (See the photos/drawings below)
  • Since the rear part is no longer affixed to the hinges, there's a small gap between the back and front parts of the housing on bottom side. Not a big problem, although it could allow for dust to enter the hinges more easily. This would probably be pretty easy to fix by connecting the two parts around the bottom center somehow, but I'll save that for a future project.
  • The side of the extensions facing the PCB is covered with insulating tape to prevent shorts.
  • Extra padding added on the left extension near the hinge to prevent it from coming in contact with the solder points for the video connector at any time in the future.
  • The uploaded designs are revised and corrected following the adjustments I made, but do make your own measurements just to be sure if you decide to go ahead and build your own :)


Some additional details and photos:


Hinge modifications:

Modifications.png

Metal plate design:

Plates 1.jpg

Plates 2.jpg

Plates 3.jpg

Note: I made a mistake with the design here. The plates extend too far towards the hinge which means that the bezel doesn't fit properly. This is fixed in the design I've uploaded (in the version I had already made, I solved it by filing down the excess, as shown below.)


Plates 4.jpg

Revised design:

Plate.png


Extra padding over the video connector:

Extra padding 1.jpg

Extra padding 2.jpg


Final assembly:

Final assembly 2.jpg


To sum up, after a whole long month of confinement to my desk at home, my trusty and beloved PowerBook is finally mobile again ❤️ :giggle:



* Around the same time, I received a PowerBook 140 from a colleague which, unlike my PowerBook 170, had a minor dent in the rear part of the display housing, so I decided to use it for the modification and spare the one from my own PowerBook in case the modification wouldn't work.

** What I ended up doing here was to discard the damaged back and revert to the original one from my PowerBook 170, while I chose to repair the less severe cracks in the front bezel with JB Weld and reinforce it with metal plates (wouldn't want to have my PowerBook 170 say "PowerBook 140" on the front :) ). While I didn't mind the look of the modification I made back in 2001, it's nice to have the original look back, and also to get rid of the aforementioned dent in plastics :)
 

Attachments

  • Plate.ai.zip
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  • Extension.ai.zip
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3lectr1cPPC

Well-known member
That's absolutely incredible! I wonder how this would compare to the 3D-printed part fix (with the additional brace behind the display) that I installed in my 145. Clearly, this is going to be way, way stronger, but the question is will the 3D-printed parts last? This is the first time I've seen a 1xx PowerBook's display housing crack in that same way that the PowerBook 1400 and many others do. Yours has seen way, way more use (and as such stress) over the years than most have, and it also has the "old school" standoff fix of drilling through the back installed that may also have added extra stress. It will be interesting to see if this issue begins happening to others over time that have been used less.
 

Byrd

Well-known member
Nice work! For someone who has taken apart a lot of old PC laptops (they come at me like magnets), its the ones with the internal skeleton/outer frame extending up the sides that retain screen hinge strength. Not many have and those that don't pretty much end with plastic crumbling into pieces, bezels popping off, one LCD (Packard Bell Pentium 1) gave me shocks as the LCD controller dropped down touching the metal shorting out on it!
 

PB170

Well-known member
That's absolutely incredible! I wonder how this would compare to the 3D-printed part fix (with the additional brace behind the display) that I installed in my 145. Clearly, this is going to be way, way stronger, but the question is will the 3D-printed parts last? This is the first time I've seen a 1xx PowerBook's display housing crack in that same way that the PowerBook 1400 and many others do. Yours has seen way, way more use (and as such stress) over the years than most have, and it also has the "old school" standoff fix of drilling through the back installed that may also have added extra stress. It will be interesting to see if this issue begins happening to others over time that have been used less.

Interesting. Did you document it anywhere? The only solution I’ve come across this far is 3D printed replacements for the screw inserts.

Regarding the longevity, both the front and back part of the housing showed cracks at around the same time, so I don’t think the old drilling fix affected it that much. The repair and reinforcement with JB Weld that I made in 2020 held together for two years of daily use, so that may be an indication, depending on how you mounted the parts to the plastics, in combination with the texture of the surfaces, though I believe new plastic parts probably are a better reinforcement than just JB Weld, strong as it is.
 

3lectr1cPPC

Well-known member
I’m talking about the screw insert 3D print. There are 2 versions of the design, one with a support piece that extends behind the screen and one that doesn’t.
 

3lectr1cPPC

Well-known member
I just thought of something, if we can 3D print metal now, would it be possible to manufacture new hinges for the PowerBook G3 Wallstreet? It would probably be a more difficult process to get those made, but is it doable?
 

AndiS

Well-known member
Regarding printing metal hinges, albeit not for a Laptop. It is possible as can be seen in this blog article of a friend of mine: server cabinet with style - scroll down for pictures of the hinges. The text is german and english.

They're made of steel and usually price is prohibitively expensive. If you work for a company that manufactures for aerospace, things are a little different ;-)
 
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