I am attempting to rehabilitate a Sonic 6 for a friend of mine. The keyboard produces triggers but will not control pitch of the two oscillators.
I have a schematic and would like to know of a good place on the board to
measure CV. What is the component number of the keyboard holding capacitor?
Has anyone seen this type of fault before?
fred
I am in no way a tech, but these sorts of problems can be caused by some prone-to-fail connector that exists in the Sonic Six! Someone like Kevin Lightner could probably explain quite well, but there is, according to the tech that fixed mine, a large connector within them that, when bad, causes a lot of keyboard CV to pitch problems, as it did with my second oscillator.
My Sonic Six had a similar problem where the 2nd oscillator wouldn’t follow the keyboard. The LFO, Osc 1, and external Osc input would all control Osc 2, but it wouldn’t respond to Keyboard CV at all.
I found this problem mentioned in the Service manual and it recommended replacing two capacitors.
I never attemted this repair because the entire PCB board was rivetted together and would have required breaking these rivets in order to access the board. So I let it be.
If you don’t have a copy of the service manual with it’s trouble-shooting section (which is pretty exstensive), I can e-mail it to you or tell you where to find it. Just send me a private message or post again here, and I’ll try to find this file for you.
Thanks for the replys guys.
I have both the service and operating manuals. I have found a 741 op amp
in the keyboard amplifier circuit that appears NFG so I will try replacing that
for starters.
cheers
fred