Any Yamaha CS-30 owners/techs out there? ENV 3 not working

Jefro · Joined: Oct 20, 2004 Posts: 9 Location: Aurora CO

I also posted this to the mod wiggles forums to see if anyone there can help...

I just picked up a Yamaha CS-30 from overseas. After going over all of it’s features, I found a couple issues. First is that it needs to be recapped. No surprise there for a synth that seems to have been largely untouched internally since it left Yamaha in 1984.

I’ve also found ENV 3 to be non-functional, I assume that as a result of the bad capacitors, the VCA chip in the ENV circuit has been taken out of commission. Specifically, IC11 on the sequencer board. I’ve poked around with a multimeter which is how I came to this conclusion, but is there a specific test I can do to find out if the IG00151 is really the culprit? More importantly, can I perform this text without removing that chip from it’s home? I have some stuck screws that’s going to make removing that chip a real pain, which brings up my next question. Assuming the VCA chip is bad, I think I can delsoder it without worrying about those screws, but I’d have to replace it from the bottom side of the board. Physically, this isn’t an issue due to it’s sil configuration, but is there another reason why I shouldn’t try to do it this way?

Any help is appreciated for this bummed new CS-30 owner.

gregcomposition · Joined: Oct 20, 2013 Posts: 20 Location: Poland

Sorry, I don't own a CS-30, but I do have a CS-10 and a CS-20M and once replaced IG00156. In your case, I would probably start by measuring the voltage levels present on the different pins of all the AMP chips (IC9, IC10, IC11). These are three identical envelope circuits, so this can be checked by analogy and any voltage deviation indicates a system malfunction. This way you'll have a nice reference list to identify the problem Smile

Good luck.