A500+ doesn't start with A590

[F0LLETT]

The A500+ starts independently, but when I connect the A590 HDD the A500+ green light doesn't turn on. The HD spins up and gets power. Switch is on 1 which is autoboot. I should add that the original A590 PSU did not provide power, so I went ahead with what I suspect is a vintage internal PSU I found lying around that had the same connector modded onto it, which at least gave power to the unit.

You sure its an a590? as they dont have switches. GVP HD+ does.

[F0LLETT]

The A590 definitely has a set of 4 DIP switches at the back.

Well I never, learn something new every day. Had one for around 3 years and never even knew it coud add fast ram.
Spose when your a kid, things like that dont interest you. Aslong as you can fill your massive 20MB HDD with games, .

Yes, power light doesn't turn on. PSU 5V output at fault? I'll check with a multimeter. If not, could a short occur on the A590-side? Capacitor that turns short instead of open?

Might sound silly, you cleaned edge connector? I have seen some wierd and crazy issues with dirty edge connector.