See above :) Found the darn things on the web about a year ago, didn't
save them (d'oh!) and now can't find them...
I got them off the net years ago (before there was a web...), but from
what I remember the quality was very poor, and it was almost easier to
manage without them...
(the audio interference on this one in front of me doesn't go away with
the audio lead disconnected, so it's not the usual problem of the audio
cable picking up noise)
Well, if the noise is not getting in via the audio input cable, the next
obvious plavce for it to get into the amplifer is via the power lines. I
would check the decoupling capacitors...
Take caee working ona Vectrex. The deflection amplifier chip (LM379) is
almost pure unobtainium, and there is no simple substitute.
There are also high voltages on the CRT, of course, but replacement
hackers are a lot easier to find than LM379s ;-)
-tony