Proteus 2000 128 Voice Expandable Sound Module
This Little wonderous bit of kit landed on the bench today. MIDI inputs and all kinds of stuff. The fault reported was very low analogue output. Not having anything MIDI lying around, how was I going to test it? Tried to interface my 1950s BSR turntable to one of the MIFDI inputs, but no, wasn’t having it.
Luckily, all the software stuff was working and manage to find a demo program. Set that up to run and connected an amplifier to the outputs. Sure enough, heard a really quiet bit of music.
Working backwards, found a sort of analogue signal coming out of one of the D to A converters. Something basic going on here I reckon. So I deployed the finger test to the ICs on the main board. After I had stopped blaspheming, I looked at the little 78M08 regulator that should have been providing one side of the +8 and -8 V to the analogue audio stages. It was generating more heat than the Sun itself. So, out with that and a grown up non SMD version fitted. Also had to replace a SMD capacitor which was short circuit.
Now when I run the demo programs, we had great loud music, the sort of stuff you could play when you go out mugging someone or selling drugs.