Another quickish update on two of my systems.
The Microbee is happily working now. I swapped out an underpowered PSU for a more “meaty” one and now it’s booting reliably and is able to load games off my nearby Android phone. I just use the built in Android playback app to playback WAV recordings of Microbee software. I successfully played a range of games including Frogger.
To get Frogger to work, I had to build a joystick adapter, I built one according to the instructions in the Microbee Engineering Notebook. (Page 10)
This is a simple resistor array. across some inputs, so was a nice easy afternoon project. The original design suggested cutting the end off an Atari compatible joystick. Instead I just added a DE-9 socket so I could switch and change which joystick I wanted to use. It was a cheap and easy upgrade and I am happy with the way it looks!
Commodore PET 4032
This one scared me a lot. The age of the equipment. The integrated CRT. The power supply being integrated with the motherboard. So much to go wrong! I spend the week cleaning and cleaning and cleaning and cleaning the board. I initially brushed it with antistatic brushes to get most of the dust off it. (About a tablespoon of dust and a dust bunny of fluff the size of a golfball).
I then attacked it with isopropyl alcohol and a toothbrush. That got more of it off, but I ended up having to use distilled water on a brush, followed by isopropyl, followed by a cloth to wipe up what was left. It’s still got a thin residue of caked on dust on it.
After that I checked the rectifier diodes (OK) and then checked the voltages out of the transformer.
They looked OK so it was time to turn it on and…
Well that’s better than I expected to be brutally honest. There’s a cursor visible in there, and I was able to type in a “program” and see some of the garbled characters changing.
At this point I’m suspecting either a corrupt character ROM or bad Video RAM. Not sure which. More investigation will be required.