paulrickardsTroubleshooting a Macintosh Portable trackball. When I last used it only 1 axis worked. Now neither work. But the button still does so this tells me that at least ADB is working? Is it the LEDs? Caps? Something else?
Tested the caps, they’re fine. The rubber rollers turn the wheels fine. The IR camera trick doesn’t work here, the IR LEDs are pulsed and it has a power saving function to slow the pulsing way down at rest.
Scoped the Y axis IR detectors and it looks OK (5Khz square wave, amplitude changes with movement). However the X axis did not match. Very much lower in voltage.
I also noticed clicking the button changed the traces. I thought this was another failure point but I think it’s just the low power mode kicking in.
Working with @techknight I searched my Apple mice for one made by Logitech. This one begins with LT (for Logitech!) and is basically exactly as the same parts as the Portable trackball (also made by Logitech). A working donor!
I replaced the two IR detectors and emitters for the X axis and the trackball sprung to life! 🎉 😎
To confirm, I put the other IR parts back in the mouse and it exhibits the same symptoms.
Peter Leonard@paulrickards Interesting! Wonder if was the senders or the receivers?
@pleonard I swapped in the detectors first and tested the trackball. It showed the same symptom. It started working after the emitters were installed.
So I think it’s at least one or more of the IR emitters for sure, maybe detector(s) too.