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Juno 60 with no oscillator output

Posted: Sat Apr 15, 2017 6:49 pm
by syntheticsolutions
I have a Juno 60 here and it has recently lost all signal coming from the oscillators :(

The noise still works as does the chorus, presets and all modulation.

Any ideas where to start with finding the fault?

Re: Juno 60 with no oscillator output

Posted: Sat Apr 15, 2017 7:05 pm
by ninja6485
Can you get self oscillation noise from the filter? Also, what do the lights above the buttons do?

The buttons are probably the cheapest and easiest fix - I would make sure it's not a button / knob / switch problem first, then proceed through trouble shooting dry joints and other connections, then major component failure.

If there's gunk blocking the connections the buttons are supposed to make, pressing them might not turn the oscillators on at all. The lights aren't always a good indication of what the switch is doing either btw: my arpeggio light will stay on sometimes even when the switch is off, until I jiggle the button. If they were working perfectly before, the all 3 suddenly stopped working all at once, it might be an indication it's not button gunk, but hey, you never know!

Re: Juno 60 with no oscillator output

Posted: Sat Apr 15, 2017 7:21 pm
by syntheticsolutions
Thanks for the reply,

The buttons are all very snappy and the LED's are very responsive to depression. There are no signs of misbehaviour with the buttons or the respective LED's, in fact, the front panel is incredibly well looked after and boasts clean faders and switches.

The VCF does indeed self oscillate at full resonance.

My guess is that I need to find where the input source meets the VCF and investigate further as the noise and all other functions after the VCF seem to work fine leading me to believe the VCO outputs are not reaching the filter :(

Re: Juno 60 with no oscillator output

Posted: Sun Apr 16, 2017 3:48 pm
by ninja6485
I think you're on the right track with that. Wonder if there's a schematic easily available online?

That's also good I formation about the buttons. It's probably not them, but the part that needs to be clean is the contact portion inside the synth. You might not be able to see if a layer of dust or grime has built up over the contact patch until you open it up. Also, if they were pressed hard, look for damaged solder connections going from there to the oscillator itself. Aside from that, and the path you're following with the oscillator/VCF path, we've reached the limit of my synth tech abilities. Hopefully someone else has some experience or ideas that can help as well!