Re: -28V on a Space Duel board

Dan Todd wrote:
>
> Anyone out there familiar with the Space Duel board? There is a test terminal
> for -28V, which is only at -15 or so on mine. I tried following it back and
> cannot determine the origin of the -28V. Could someone explain it to me?
>
> Thanks,
> Dan

The -28V is actually made by the -15V supply. There is a 555 timer that
runs at a continous frequency and goes into a capacitor voltage doubler.
If the 555 is running, then your caps are probably dried out
(electrolytic). I think that Al has all the schems up at
www.spies.com/arcade
Received on Sun May 23 22:41:17 1999