Crumar Bit One

“For sale is a Crumar Bit One synth that I have been trying to fix for a friend. This is a six voice analogue polysynth with digitally controlled oscillators, Curtis 3328 24dB/octave analogue filters and LM13700 VCA’s. But there is a problem….

The DCO’s appear to be working correctly and can be edited from the front panel and the signal is being passed through the filters and VCA’s (you can hear the DCO’s clearly on the output). However the filters and VCA’s do not respond to their control signals. These signals are generated digitally and multiplexed through a single DAC/op amp… my initial suspects…. but replacing them did not solve the problem. I should also say the backup battery has been replaced and the factory presets re-loaded from a “cassette tape” wav file.
I’ve done about all I can so it’s time to pass on to someone else. Fix the problem and you will have a fantastic rich (and real) 80’s analogue poly.”
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