PowerBook 180c TRACKBALL Repair Help Needed

[JDW]

I recently acquired a PowerBook 180c and found it's trackball didn't produce any vertical arrow pointer movement, so I cleaned the ball, rollers, and the red-eye gizmos, but that didn't do any good. When I use my finger on each roller, the arrow pointer moves just fine horizontally and vertically. But when the ball is used, movement is imperfect horizontally and pretty much non-existent vertically. I made the following video for crystal clarity. Look forward to hearing thoughts and advice, especially from you experienced Powerbook owners and repair geeks!

 

[Kai Robinson]

Is the ball itself out of round?

 

[JDW]

I checked the ball with my precision Mitsutoyo calipers just now, Kai, and it's 30.03mm in diameter nominal, deviating only by +/-0.01mm as I rolled it around and around in the calipers. Roundness is excellent. Surface is extremely smooth, with no pitting or flaws that I can detect.

 

[Kai Robinson]

The only thing i can think of then, is the friction on the roller itself, the surface might be too worn/smooth - can you replace the roller with a piece of silicone vacuum hose, or similar?

 

[phunguss]

Is there a 3rd wheel that is supposed to put pressure against the ball to the two rollers? Maybe the spring is missing?

 

[JDW]

@Kai Robinson
Before I embark upon disassembling the Trackball Assembly (a more complex job than on a Mac Portable and the reason I started this thread), is because I have no experience doing this, and I have read extensively about broken standoffs caused by merely opening the machine in the first place, even when done very carefully. So I was hoping that somebody who does have such experience in disassembling this entire trackball unit, not merely removing the unit but disassembling the unit, would chime in with details and precautions for me.

@phunguss
I am new to these older power books and I have zero experience so I have no idea if there’s a missing wheel or spring or anything of that sort, and I’m hard pressed to find even photos or videos of a fully disassembled track ball assembly. I searched it for hours in vain yesterday for all of that before I started this thread. It’s almost like nobody out there has ever disassembled a PowerBook trackball unit. I find that rather odd.

Here is a second reason why my track ball assembly needs to be torn apart, assuming this second problem can even be fixed — the left side of the upper and lower buttons have issues, and I clearly show in this short video…

Tagging: @This Does Not Compute , @techknight

 

[This Does Not Compute]

Generally speaking the 100-series PowerBooks are easy to work on. Just remove all the screws from the bottom and the one on the back (next to the modem slot), then separate the top case from the bottom. If you hinge it open from the back, you can lift the top case up just enough to reach in and disconnect the single ribbon cable that keeps them together. From there, individual components inside are straightforward to access. IIRC the trackball assembly is screwed to the underside of the top case.

 

[Garrett]

I’ve had this issue before, and found that it’s made worse by cleaning the blue rollers with IPA. They’re slipping on your metal shafts. Now any PowerBook I work on automatically gets new silicone rollers.

If I recall, you’ve done this job to your Macintosh Portable. Good news- the PowerBook 1xx series can use the same size silicone tubing! You’ll have to pop the top case off, but it’s not a terrible job. Just go slow when separating the halves, and use a tool to separate the ribbon cable which connects the logic board to the interconnect board. They don’t like to be flexed any extra than is necessary.

 

[JDW]

Generally speaking the 100-series PowerBooks are easy to work on.

I’ve seen the removal of the trackball assembly from the case and therefore understand how to do that, but I’ve yet to find a single photo on the tear down of that trackball assembly, which is rather interesting.

Have you ever disassembled the trackball assembly?

…you’ve done this job to your Macintosh Portable. Good news- the PowerBook 1xx series can use the same size silicone tubing!

Yes, and I mentioned my having done that in my earlier posts. But as I said, in the case of the Mac Portable, the rollers didn’t move the arrow pointer when touched by my finger, and they were falling apart too, so I replaced them. And it’s easy to access those parts on the Portable too. But if you watch the videos I posted in this thread, you will see that the PB180c differs from the Portable. As shown in my video in this thread, the ball has trouble moving the rollers but my finger moves the rollers AND the arrow pointer. That is the odd part that differs from the Portable.

In addition to all this, the left side of both buttons have issues, as shown in my most recent video in this thread.

 

[Stephen]

The IPA probably dried out the blue rubber, possibly causing it to also shrink a bit. As others have said, I too would guess that they’re not “sticking” to the ball as well anymore

 

[JDW]

The IPA probably dried out the blue rubber, possibly causing it to also shrink a bit.

I don’t disagree with that, but the rollers behaved 100% the same before and after my IPA cleaning. Meaning, when using my finger on either roller, the arrow pointer moved just fine on screen; but when I put the ball in, the behavior was bad, as shown in the recent video I posted in this thread.

 

[Stephen]

I don’t disagree with that, but the rollers behaved 100% the same before and after my IPA cleaning. Meaning, when using my finger on either roller, the arrow pointer moved just fine on screen; but when I put the ball in, the behavior was bad, as shown in the recent video I posted in this thread.

I anticipate that the red spheres located inside the computer serve as positional fixtures for the track ball.

If the blue rollers have dried out and shrunk then the distance from the track ball’s external face to the rollers has now increased, reducing contact or eliminating it entirely.

just my guess

 

[Yoda]

Surely this indicates the issue is in the contact face between the roller and the ball? Clearly the roller in itself is working, but if that contact face has little or no friction, is a fraction too small in diameter due to wear/shrinkage, is slightly misaligned with the pin sitting too low in the plastic mounting, or the spring-loading is too weak, the roller won't move when the ball does.

The fact the left-side of both top and bottom buttons seem lower and inoperative suggests it may have sustained some stress damage, and that may have deformed the roller's mounting pin, or affected the spring loading which tensions it against the ball.