Can I calibrate Aftertouch on Yamaha KX-88

Syntaur
1

I recently purchased a KX-88. But I find the aftertouch insensitive. I’ve calibrated this on a DX7. But I can’t find parameters for aftertouch nor can I find a potentiometer in the Service manual for it. Hope someone can help me out! Would a new stoffer felt solve the problem?!?

2

I am not aware of any way to calibrate this. A quick scan of the service manual did not show any adjustment.

3

It could be that the aftertouch strip is wearing out.

4

Dear Sam,
Thanks fir your quick response!
Is there a way to measure this decay?
Impedance for instance?!?
The aftertouch strip lies underneath the felt strip,
could replacing that be sufficiënt?
Kind Regards ,
Eric

5

That strip should measure infinite resistance until you press on it, and then the resistance should drop, varying according to how hard you press. (There are two wires that connect from the strip to the main board.) If I recall, it should drop to 10K ohms or so with pressure.

I took another look at a main board photo, and then the schematic, and there are two trim pots on the main board (VR1 and VR2 - I think they are the only trim pots), and they are indeed associated with the aftertouch strip. You might want to mark their current positions, then see if you can adjust for better response.

It could also be a physical issue, of the felt being too worn (and perhaps then the key bottoms out without putting pressure on the strip), or perhaps something with the strip itself.

6

Dear Sam,
Thanks for all the info, I’ll look into it all.
And hope it will make the aftertouch more smoother!
Strange that there is no info on the trim pots in the service manual, but I’m glad you found them.
The calibration will probably be similair as for the DX7!
Thanks for all your info and have a great weekend!
Kind Regards drom Holland!
Eric

7

Dear Sam,
You’re the best!
This exactly what I was looping for, similair to the DX7 trim pots.
The white keys don’t respond as well as the black keys, but I think this due to worn felt.
Kind Regards,
Eric

8

Dear Sam,
Does Syntaur sell the replacement felt for the KX-88?
Kind Regards ,
Eric