So I recently rescued an Apple PowerBook 170 from ca. 1991. I couldn’t find the power supply, but fortunately the power connector is just a standard DC jack requiring 7.5V - so I removed the (probably broken and internally leaking) NiCd battery.
So I took a DC jack, hooked it up to my lab supply …and bingo! Started up right away!
However the mouse ball didn’t worked initially, turns out it was dirty. Anyone still remember those days when you had to clean your mouse wheels from time to time? After cleaning the internal wheel up a little bit the mouse worked as well.
This system has expansion memory installed, a whole 8MB (the maximum configuration for the PowerBook 170).
It also has Excel and this 1988’s Tetris installed.
All in all nice to know that it still works! Now I have to get a power supply for it, my (linear) lab power supply gets extremely
hot from running this at 1.5A because the required 7.5V is just above the lower transformer tap, the next higher being 16V, so
(16V-7.5V)*1.5A = 12 watts into a passive heat sink. Fortunately any 7.5V plug pack DC power supply will work.