Patches and discussion for Ensoniq VFX family

I thought I had a schematic, but nothing more than the service manual and it's not much help. I found one on the internet but it was hardly legible. I might have to open my SD1 and see if I draw one of my own. 

I ran across a rather interesting thread on a forum that has some troubleshooting tips. The poster describes a different Motorola chip that is responsible for aftertouch but without opening my SD1 I didn't follow. http://www.vintagesynth.com/forum/viewtopic.php?f=5&t=96381

He does make some (informed?) guesses about the 68HC11 that may (or may not) explain why your new one didn't work although I doubt that code is stored in the EEPROM. Calibration data seems more likely to me if there is an external ROM that can be changed. (I remember making copies of my ROMS, and I think I pulled one from the keyboard.)

Sent from my iPhone

> On Mar 28, 2017, at 12:33 PM, Steve Wahl steve@... [Ensoniq-VFX-SD] <Ensoniq-VFX-SD@yahoogroups.com> wrote:
> 
> On Tue, Mar 28, 2017 at 01:41:19AM +0000, wjwilcox@... [Ensoniq-VFX-SD] wrote:
> > A replacement 68HC11A1P keybed microcontroller arrived today and was installed. Unfortunately, it did not solve the problem. On the bright side, I didn't make anything worse....
> 
> This makes sense to me. If my understanding of the way the keyboard
> functions is correct (the distance between the coils on the board and
> the metal pieces in the keys is measured, somewhat similar to a metal
> detector, distance X is key up, smaller distance Y is key down, and
> even smaller distance Z means pushed into aftertouch zone), the
> processor being able to figure out that a key is pressed but not be
> able to figure out whether it should or should not be considered to be
> in the aftertouch zone would be an odd thing, considering the digital
> function of the processor itself.
> 
> Have you read Ensoniq Service Builletin 12? It gives a lot of
> keyboard information. They describe four KPC versions and different
> coil board types. I find this note in there: "Remember that a KPC
> board can only be replaced with the whole keyboard assembly as it
> contains information specific to its particular coil boards and keys
> in its memory." I cannot decide if the note means they just know
> which style coil board is attached, or if there was some factory
> calibration proceedure that stored information for the particular
> keyboard and analog parts on the coil boards.
> 
> I read the datasheet for the 68HC11A1P, it has 512 bytes of EEPROM.
> That may have stored callibration information.
> 
> I wish there was a complete schematic of the keyboard somewhere. The
> one I can find on the web is missing a page or two. But I probably
> wouldn't be able to understand it without someone to explain it to me
> anyway.
> 
> Since the problem seems to be common to all the keys, a guy might look
> at the schematic and examine any analog components that seem to be
> common to all keys, and check to see if they've drifted far out of
> spec (perhaps zapped by the power surge you described). 
> 
> You said you had an aquaintance who was a former Ensoniq engineer?
> That's probably a better resource than anyone here, certainly better
> than myself.
> 
> But, at this point I fear you may be looking at a keyboard transplant,
> or a Frankensoniq built from yours and another donor. :-(
> 
> --> Steve
> 
> -- 
> Steve Wahl steve@...
> 
> Real men don't take backups, they just "mv home.tar.gz
> olsen_twins_hottub.mpg" and share it on KaZaA -- Unknown
>