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Amitech Amiga Mouse Repair

I have an Amiga mouse that behaved so poorly that it was unusable. The symptom was that movement was barely detected, if at all at some times. After digging around on the Internet I found that one possible cause is the IR emitter and IR photo-transistors that are used to generate the quadrature encoder pulses.

I ordered replacements from my local dealer, specifically:
* OP 750A - IR phototransistor 850 nm 30 V Side Looking, Optek

IR phototransistors

* IRL 81A - IR emitter 860nm 100mA 1.3V THT, Osram Opto Semiconductors

IR emitters

And soldered on these replacements:

Amitech mouse replacements

This is indeed what was causing the problems and the mouse is now working again:

Amitech Denmark Logo

Topic: Repair, by Kjetil @ 03/10-2020, Article Link