Source Gone Haywire

R.G. Keen keen at
Wed Aug 21 23:00:09 CEST 1996

>  The only sound it makes now is a short (three seconds) burst imediately
>  after it's turned on. Then it peters out to a barely audiable signal.
>  It was working fine before this started.
>   Do you know what the problem is?
Sounds like one of two possibilities. A short period of operation - any
sound at all - followed by silence is usually caused by something 
operating a little bit as the power supplies come up to full voltage.
This can be a bad power supply section as in either the (+) or (-) 
voltage in a bipolar supply,  or alternately, something can be broken,
like a capacitor, and the circuit only passes through a small "window"
of the power supply range as it comes up where the broken component
doesn't hurt things too much. 

Check the power supplies for proper voltage, usually +/- 12 to 15 volts
in a synth, and then go looking for the same voltages on the power
supply pins of the IC's (possibly bad wiring). If that checks out OK, 
you're going to have to dig through the components to determine what
is broken inside the signal circuits.

Good luck, and happy hunting...


More information about the Synth-diy mailing list