After buying one of these as spares or repairs to try and fix up, I hit a bit of a stumbling block when I discovered the internal DC-DC converter seemed to be dead. I looked around for the schematics but didn’t have any luck. So I decided to get a second one and combine the two using the best parts of each, and now I have a fully working one I can measure the voltages and maybe resurrect the other one in the future.
But for now I have this one fully functional with the 40mb Hard Drive and a 4MB Ram expansion. Looking at the contents on the HDD it seems it once belonged to Woolworths! I guess they didn’t have proper disposal procedures back then.
Whilst I had it in pieces, I also fixed the common issue with the Dallas RTC chip being dead. This means it doesn’t remember any of its settings after you turn it off, and you then have to boot it from floppy to configure the HDD.
I’ve replaced it with a modern alternative so now the battery is easily replaceable in the future.