In March 2012 we attempted to re-boot my circa 1978 NASCOM 1. (Video to follow). The attempt was not successful and we may have damaged the main board. A 2.2uF capacitor in the PSU burnt out (lots of smoke) on power up. After replacing this and a suspect 10ohm 10W resister, the PSU appeared to present incorrect voltage to the main board. This may have caused irrevocable damage.
It looks like we have broken the first rule of engineering. Disconnect/unsolder old power supplies first, test them thoroughly and only then re-connect them to the electronics. If we make more progress we'll post it here.