[sdiy] Arp Solina with excessive chorus noise

[tprivitera at nc.rr.com]

Hi all,

I recently picked up a 70's Arp Solina String Ensemble. It has the button on the right cheek block to turn the chorus on/off and it is not the later version with LEDs.

It's in pretty good condition, every function works and it sounds great, but there is, in my opinion, excessive noise and 'swooshing' when the chorus/modulation circuit is engaged.  It is dead silent with the chorus turned off.  Not a big deal when you are playing notes or chords, but enough to be annoying when it's idling.

I downloaded the service manual/schematics and it looks like there are adjustment pots on the modulation boards.  Anyone had one with a similar issue adjust these or can suggest some ideas to reduce the noise?  I will be re-capping the power supply later this week for preventative maintenance, as I do with all my synths, combo organs, etc.

Thanks in advance,
Tim