Hi Cynthia--I also do design work for Paul Schrieber of SynthTech, so
I'm also making stuff on the modular front. Anyway:
On Tue, 26 Aug 2003, Cynthia Webster wrote:
> Wow! My hat is off to you crow, Well done!
> (What a monumental undertaking you have done!)
Well, it needed doing a long time ago..but I am very good at
procrastination, especially when there are more pressing engineering tasks
at hand. The original KLM-367 has a serious design flaw in that 1) they
put a NiCad battery on the pcb and 2) put it near critical circuitry. I
finally got fed up with spending an average of 3 hours per KLM-367 repair,
and decided that the same 3 hours would yield a new, assembled board.
> In fact I've been wanting to add jacks to my P6 to interface it with my
> modular... Simple mods that I've been wanting to do is add an LED for the
> third LFO and make the LFO outputs available, as well as converting the
> trigger from Moog S-type over to um, "Arp" type.
Well, 2 LFOs happen to be on the KLM-367: the PWM MG (Korg calls LFOs
MGs as you know) and the routable (VCO/VCF/VCA) MG. Not much would be
needed to provide outputs for either of these.
> There are many other mods that would be cool, in fact If anyone has some
> cool mods they've done I'd love to hear about them. (As you can see here I
> am not a purist, as far as keeping my Poly's "stock" looking).
>
> (It would be cool if your new PCB layout facilitated a few mods easily?)
Well, the initial prototypes are direct KLM-367 clones. Once I verify
the clone boards in fact work correctly, I'll start adding in option
features. For example, there are two unused MUX S/H outputs that beg to
have S/H circuitry added so as to create two new control voltage
parameters. Ricard Wolf used them for pitchbend and mod wheel CVs, I
believe. I would probably provide circuitry for the same.
Down the road I want to change CPUs as 8748s are getting harder to come
by. With a CPU change, I can start to do things like add MIDI, integrate
the key assigner (a separate CPU on the KLM-366 board) and generally make
things more efficient such as eliminate the battery-backed SRAM and use
the new MCU's internal user data flashrom area to store patches..many more
than 32 patches, btw. While doing this I would switch to surface-mount
for most of the board's parts: I can get a factory to build SMD boards
∗much∗ cheaper than to build TH boards.
> It's really refreshing to see this level of commitment to the machine Scott.
> I think would like to get a couple of these new boards when you have them
> made, and am Very interested in facilitating the MIDI mod as well.
>
> Do you suggest these boards just for units are found broken, or also for
> PolySixes that have already had their battery problems repaired?
I would suggest the clone boards for repair job first--thats why I made
them. For upgrading the Polysix, I would go with the next version of the
board, once I figure out what to put on it.
> I hope that I don't upset anyone here with this next comment, but...
>
> Does anyone really ~want~ to deal with that cassette interface? (Gak!)
>
> I've often thought that that entire section could be replaced with something
> much more interesting, (or even a small floppy disk drive or the little
> flash memory cards thingies that go into digital cameras in order to save
> patches).
The cassette interface takes up very little hardware (and not much code
space, either). It is about the most generic implementation of the Kansas
City Standard FSK data-to-tape I/O routine I've ever seen. I would leave
it in simply because lots of folks still have patches on tape.
Anyway, once I have a new board assembled and working I'll figure out a
repair/replacement scheme. I can probably still do the $100+old board (I
would scavenge a few esstentials off the old boards) and send a new board
to folks...we'll see.
Crow
/∗∗/