OT: Yamaha CS-50 schematic/repair?

[Cabezahead]

I'll keep it short...

I have a big old Yamaha CS-50 synth.  It sounds great - but lately it has been making a terribly obnoxious, high pitched whinining sound after it has been on for 20 minutes or so.

This leads me to think that it's a capacitor or two or ten that needs to be replaced...

Does anyone know where i can get a schematic of this beast?  Or perhaps the location of the capacitor in question (i'm thinking around the output...  somewhere near the main amp before the 1/4" jack...)

I think this is the type of case where I can spray caps with cool, compressed air or something until it stops squealing and replace the culprit - because it seems like heat is making this thing squeal.  Does that sound right?

Any help is muuuch appreciated.

-CH

[vortex]

CS-50....I bet it's a jungle in there! I hope you make it out alive!

I have no schems or advice,  I just wanted to say good luck on your journey.

[Dan N]

This is from google:

http://home.debitel.net/user/jhaible/jh_cs50.html

Looks like maybe some info of interest, especially the Old Crow link.

[Cabezahead]

Wow - I guess i'm not that good at googling...

Thanks a bunch!  Sounds like the caps are the right place to start.

Still can't find a manual that shows me how to crack this thing open though...  I have a feeling it's a lot easier than i'm trying to make it... (the picture make it look like the top part just swings open at the drop of a hat)

I'll poke at it with a fresh pair of eyes tomorrow... Thanks again!

-CH

[Cabezahead]

just got it open... two screws - real easy...

MY GOODNESS there's a lot of stuff going on in this thing...

-CH

[vortex]

Welcome to the Jungle baby!

Post a pic??

[grapefruit]

I repaired a Roland SH5 and Korg MS20 last year. Both had problems with electrolytic and/or tantalum bypass caps on the power supply rails (on various boards, not just on the power supply). I replaced the tantalums with low leakage electrolytics, but only bypass caps. Don't replace any tantalum oscillator timing caps or anything with electros. IIRC the MS20 oscillators were cross modulating and the SH5 filter circuit was oscillating...


Stew.

[Cabezahead]

Hey - thanks for that info.  I'm out of town right now, but I plan to tackle this beast when I get back.

I'll try to get a picture of the guts up - and maybe take some pictures of the changes and whatnot.

It really is impressive in there - I expected a lot of complex stuff going on... but nowhere near what's really going on in there...

Am I right in figuring that the timing caps will be hooked up to a timer chip of some sort? And those are the ones I should not replace?

-CH

[Paul Perry (Frostwave)]

I doubt there is a timer chip as such, just the 'usual' sawtooth integrator/reset thing.

[Cabezahead]

I doubt there is a timer chip as such, just the 'usual' sawtooth integrator/reset thing.

Ah. Right.  The 'usual sawtooth integrator/reset thing.' I see.

I'll have to run a search for that one.

:-)

-CH

[aron]

I have a Micro Moog, OB-1, Arp Odyssey .... all have various problems. I should go into them and start replacing electrolytics in the power supply. Poor things.