Yamaha CS6X Aftertouch Modification

[Ctopher7]

Hello:

I have the subject keyboard in my studio. It makes a great controller with its rubbery pitch and mod wheels, ribbon strip and breath controller input. It also has lots of pedal inputs and seems to have quality components.

But I find the aftertouch hard to use. It comes on too suddenly and doesn't offer much degree of control. It's more like "afterswitch" as some call it. It's usable to some degree when I change the response curve with a midi utility within my DAW. But that only helps a little.

I'm wondering if this could be modified in any way. For example, can the sensor strip be replaced or its resistance be modified or can another layer of felt be added to broaden the range of control? Unlike other keyboards with better aftertouch response, the keyboard doesn't seem to have much "play" after the keys are depressed so I'm a little doubtful that much can be done mechanically. (I've thought of replacing the keybed also but I expect that would be more trouble than it's worth, if not impossible.) Any ideas/suggestions are appreciated.

Thanks.

Chris

[Enzo]

Well, link the schematic or at least that part of it, or tell us the circuit is identical to DX7 or whatever.

Disconnect the strip and measure it with an ohm meter. Does it have a linear resistance change? Or does it indeed act as a switch? It could be faulty and a new stock one might work fine.

I have not worked on any Yamaha keys in a while, I used to see a lot of them. But if the stip is analog/linear, then the sensing circuit probably has a trim adjustment. It would just not be like Yamaha to leave one out, y'know?

Yamaha writes very thorough service manuals, and they include all teh diagnostics and adjustment procedures. If you want to keep this instrument in service for a long time, it would be worth the bucks to get the service manual.

Before looking to modify anything, you ought to find out if the existing thing is working right and is properly adjusted.

[Ctopher7]

Thanks Enzo.

There is some variation in the touch (but difficult to control), so I don't believe it is on/off. I've seen comments from others that say that Yamaha's aftertouch implementation has been poor at times so I'm doubting that it is modifiable. But to your suggestion, I have since found posts about how other synths (non-Yamaha) have taper/offset adjustments for aftertouch so I can look into that.

I found a schematic here. I couldn't see anything about the aftertouch though.

YAMAHA CS6X SCH Service Manual free download, schematics, eeprom, repair info for electronics

Thanks

Chris

[Enzo]

Page 1 upper right. Third connector down, CN10 "to LC KEYBOARD" Note the three pin connector has ground on pin 3, pin 2 is power to the AT stuff, looks like +12v dropped to about 9v. Pin 1 would be the returning aftertouch data. Note the line labeled AT (aftertouch) going up and over to pin 11 of IC16. That appears to be a multiplexer, and i will go no further, because I probably will be guessing. Oh, and as far as I can see that AVCC related to pin 1 is +5v, and with D7, it looks like it prevents the signal on pin 1 from going much over 5v.

What we don;t see is what is out at the other end of that three wire cable. On a DX7 there is a small circuit board, but that was 25 years ago.

[Ctopher7]

Hello:

Here is an update: I took the bottom panel off (50 screws later). I immediately saw Gain and Offset potentiometers on the circuit board. I could affect the response of the aftertouch with these but I could improve it only a smidgeon. There is just not that much play in the aftertouch and apparently no "room" to expand the range of touch. And mechanically, both the aftertouch strip and the key mounts are in one rigid assembly so I don't think that can be modified.

Time for a keyboard upgrade. I'm going to look at a used Kurzweil tomorrow.

Thanks.

Chris