CS-80 YM26600/26700 IC Alternatives

From circuitbending to homebrew stompboxes & synths, keep the DIY spirit alive!

Moderators: Kent, luketeaford, Joe.

Post Reply
User avatar
JonathanG
Common Wiggler
Posts: 169
Joined: Sun May 15, 2011 11:30 am

CS-80 YM26600/26700 IC Alternatives

Post by JonathanG » Tue Jan 16, 2018 12:41 pm

Has anyone ever looked into modern replacement alternatives for these fragile and rare 40-year old chips? I am wondering if it'd be possible to program an Arduino to handle key coding/assigning and D/A conversion duties on the KAS and KBC boards.
Cheers,
Jonathan

User avatar
noddyspuncture
Veteran Wiggler
Posts: 604
Joined: Wed Feb 05, 2014 6:23 pm

Re: CS-80 YM26600/26700 IC Alternatives

Post by noddyspuncture » Thu Feb 22, 2018 6:46 pm

JonathanG wrote:Has anyone ever looked into modern replacement alternatives for these fragile and rare 40-year old chips? I am wondering if it'd be possible to program an Arduino to handle key coding/assigning and D/A conversion duties on the KAS and KBC boards.
Cheers,
Jonathan
I have a friend currently working on 'recreating' those - we shall see, it's not an easy one...!

Do you think there would be demand for them...?

nvining
Common Wiggler
Posts: 118
Joined: Sun Apr 08, 2012 3:44 am

Post by nvining » Fri Feb 23, 2018 7:19 pm

Yes. Last time I had to get a YM 26700 to fix one octave of keys in my CS60, it cost me $1k.

I know Scott Rider (Old Crow) has been threatening to do one.

User avatar
Starspawn
Ultra Wiggler
Posts: 780
Joined: Tue Mar 06, 2012 8:12 pm
Location: Norway

Re: CS-80 YM26600/26700 IC Alternatives

Post by Starspawn » Sat Feb 24, 2018 3:08 am

noddyspuncture wrote:
JonathanG wrote:Has anyone ever looked into modern replacement alternatives for these fragile and rare 40-year old chips? I am wondering if it'd be possible to program an Arduino to handle key coding/assigning and D/A conversion duties on the KAS and KBC boards.
Cheers,
Jonathan
I have a friend currently working on 'recreating' those - we shall see, it's not an easy one...!

Do you think there would be demand for them...?
Recreating is one thing, adding midi is the important bit :)
Scott Rider did do the CS15, but Yamaha has several of those assigners.

User avatar
noddyspuncture
Veteran Wiggler
Posts: 604
Joined: Wed Feb 05, 2014 6:23 pm

Re: CS-80 YM26600/26700 IC Alternatives

Post by noddyspuncture » Sat Feb 24, 2018 7:32 am

Starspawn wrote: Recreating is one thing, adding midi is the important bit :)
Scott Rider did do the CS15, but Yamaha has several of those assigners.
Midi isn't important - making an exact replacement IC which will drop in place of the original is the most important - to keep these beasts running. CS60's & CS80's didn't have Midi as standard... they are a 'players' machine..! :hihi:

If you want Midi, there are kits available I think...!?

User avatar
papz
Super Deluxe Wiggler
Posts: 3588
Joined: Sat May 18, 2013 6:52 pm
Location: in a suitcase
Contact:

Post by papz » Sat Feb 24, 2018 7:46 am

nvining wrote:Yes. Last time I had to get a YM 26700 to fix one octave of keys in my CS60, it cost me $1k.
So the one you got from me was a very good bargain 8-)
Finest EMS gear service and Music Easel/208 goodies

I'm not a synths dealer and I'm not aware of an inexpensive Synthi secret market, please don't ask me if I know one for sale.
I don't offer support of any kind to people attempting to build clones of EMS equipment.

User avatar
cranleigh
Wiggling with Experience
Posts: 283
Joined: Sat Sep 17, 2011 5:03 pm

Re: CS-80 YM26600/26700 IC Alternatives

Post by cranleigh » Sat Feb 24, 2018 10:48 am

noddyspuncture wrote:
JonathanG wrote:Has anyone ever looked into modern replacement alternatives for these fragile and rare 40-year old chips? I am wondering if it'd be possible to program an Arduino to handle key coding/assigning and D/A conversion duties on the KAS and KBC boards.
Cheers,
Jonathan
I have a friend currently working on 'recreating' those - we shall see, it's not an easy one...!

Do you think there would be demand for them...?
I'd be interested for sure.

User avatar
efexor
Common Wiggler
Posts: 106
Joined: Tue Jun 16, 2015 11:10 am
Location: earth

Post by efexor » Sat Feb 24, 2018 1:48 pm

There will certainly be techs/owners who wants some of these as spare.

nvining
Common Wiggler
Posts: 118
Joined: Sun Apr 08, 2012 3:44 am

Post by nvining » Sat Feb 24, 2018 2:44 pm

I will note that the YM26600 and YM26700 that I bought for $1000 did come with an entire non-operational CS50 around them. ;) So actually, it was a pretty good deal :)

What I would do, ideally, is replace the entire KAS board - take both the YM26600 and YM26700 out of the equation. That'd be where I'd put in MIDI as well. I don't know

The biggest two issues are that the level switching is a pain in the ass (although you can get a line driver shifter to fix this), and the fact that I have no clue how the damned clock works in the CS80. The manual is thoroughly incomprehensible. If somebody can explain that to me, and provide me with a board that does the line shifting and includes a suitable ARM part to control it all with, I'm happy to write the firmware. I'm just not good enough at electronics to wrestle the analog side of it.

User avatar
Starspawn
Ultra Wiggler
Posts: 780
Joined: Tue Mar 06, 2012 8:12 pm
Location: Norway

Post by Starspawn » Sat Feb 24, 2018 3:06 pm

Pretty much what old crow did, maybe send him a message ;)
http://www.cs80.com/SSK/

User avatar
cranleigh
Wiggling with Experience
Posts: 283
Joined: Sat Sep 17, 2011 5:03 pm

Post by cranleigh » Sat Feb 24, 2018 4:28 pm

Considering that the Kenton kit is UKP 474, and does nothing to address the ole ticking-time-bomb proprietary IC issue, a replacement KAS board/midi interface would be very desirable to a lot of owners. You and Scott should team up! I'd pay a few hundred for such a thing, for sure.

User avatar
oldcrow
Super Deluxe Wiggler
Posts: 1067
Joined: Sun Nov 20, 2011 4:05 pm
Location: Chicago, IL USA
Contact:

Post by oldcrow » Sun Feb 25, 2018 12:41 am

I got sidetracked onto other stuff, but I still want to make this thing. It may be better to do a board-level replacement vs. chip-level. --Crow

User avatar
JonathanG
Common Wiggler
Posts: 169
Joined: Sun May 15, 2011 11:30 am

Post by JonathanG » Sun Feb 25, 2018 8:17 pm

oldcrow wrote:I got sidetracked onto other stuff, but I still want to make this thing. It may be better to do a board-level replacement vs. chip-level. --Crow
Hey Crow, thanks for chiming in. Quick question: any chance you know if these resistances I'm getting between the power rails on my CS-80 and ground are normal?:

+15V = 70.3 Ohms
-15V = 64.5 Ohms
+8.5V = 337 Ohms
-6.5V = 878 Ohms
+10.6V = 540 Ohms

I'm thinking my -6.5V could be low as a friend is getting 3.95 Kohms on his currently working unit, as well as 456 Ohms on the +8.5.

User avatar
cranleigh
Wiggling with Experience
Posts: 283
Joined: Sat Sep 17, 2011 5:03 pm

Post by cranleigh » Thu Oct 25, 2018 4:58 pm

Just bumping this one on behalf of the CS owners who would love to see a replacement KAS board/midi interface. If anyone could build one, I bet there'd be a lot of takers! :guinness:

User avatar
devinw1
Super Deluxe Wiggler
Posts: 1931
Joined: Tue Aug 07, 2018 11:20 am
Location: Portland, OR
Contact:

Post by devinw1 » Thu Oct 25, 2018 5:38 pm

Seems like the way to do it would be to offer a whole PCB replacement for the KAS board, which includes a processor with the appropriate firmware, and would include MIDI. Kill both the oddball custom chips in one swoop and add features.

This is way beyond my scope, but sounds really cool. As many have said, if there's a guy who's gonna pull it off - it's oldcrow. Haha.

Post Reply

Return to “Music Tech DIY”