Yamaha CS-5

[untune]

Howdy all,

Long time since I've been round these parts... just managed to get hold of a Yamaha CS-5 analogue mono synth and it sounds lovely.  Couple of scratchy pots and a dodgy connection on one of the switches which needs looking at but other than that it's in great nick.  I'm not going to bend it, but it does appear to have drifted in tuning.  I've checked with a tuner and each key is bang on in terms of scaling (ie you can go up all 3 octaves and every key is in tune with the exception of the first 3 or 4... slightly sharp but not enough to notice, maybe that's just the wave being a bit too low/complex for the tuner plugin to measure accurately, I don't know)

So it would seem that the 'master' tuning has drifted.  I've managed to adjust the tuning with the pitch control to get it right for now, so technically it would be fine but I lose the use of the pitch bend which doesn't seem that useful anyway.  But I'd like to get it operating as it should.

Even though due to it's age it probably needs to be completely re-capped I'd prefer to avoid doing that... so does anyone know anything about it, if there's a simple way to get things running properly?  Can't find a service manual, no idea of there's a trimpot or the like somewhere, or maybe it's the power supply (read this is often the culprit on old synths)

Any ideas?

Cheers!

[Circuitbenders]

is everyone else using a different google to me?  The second result for 'yamaha cs5 service manual'

http://elektrotanya.com/yamaha_cs-5_synthesizer_sm.pdf/download.html

That appears to be in japanese but if you look at the section with the VCO heading you can see the test points and several frequencies you need to be seeing when you adjust VR2,VR3 and VR4

[Gordonjcp]

Don't "re-cap" it.  It will never work right.  Capacitors don't really fail in equipment like this.  Just leave it the hell alone if it's working.