Yamaha CS80

Hello, I hate joining a group just to get a question answered or problem solved, so I'll try to stick around and be as helpful as I can be.

In addition to the other old synths and effetcs I've accumulated, I have a CS-80 here that I'm repairing.

It's got a weird problem and I wonder if anyone has seen this before.  It plays normally as long as I don't pres any keys in the topmost octave.

I popped the hood and traced it down to the YM26700 D/A converter on the KAS board.  Well, at least I think that's the problem.  Here's what I measured:

pins 19-30 are getting the correct voltages for each key in the octave,
pins 13-18 have the correct voltages for the octaves (0.125 through 4),
pins 5-8 are reacting correcting for each key in the octave,
pins 9-11 are reacting correctly to indicate the octaves,

pins 31-38 (channels 1-8) output the correct voltages up and down the keyboard until I press keys in the upper octave.  If I press a key up there, the voltage reading drops into the negative (i.e. -2.5v, 3.5v, etc).

Could there be anything outside the 26700 causing this behavior?

If not, are there any sources for a YM26700?

If not, who wants to buy a CS50 or 60 with me for parts?

Oh - I do happen to have a handful of lever switches, keys (white and black), some panel buttons w. bulbs, and the entire 4-bank 'memory' board that fits under the flip top panel, so I'm not coming here completely empty handed...

thanks,

Tom

Hi Tom, I'm sorry i can't help you cause I'm no tech at all. Just a keyboard player who happens to own one of these monsters. And I'm seriously considering the option of getting rid of it since I'm not using it anymore these days. So if any of you out there want more info on this just write me through the group. I'll be glad to tell you about.
François 
P.S. I'm in MONTRÉAL, Qc, Canada

--- En date de : Mar, 3.3.09, tmoravan <moravanskyt@saic.com> a écrit :

De: tmoravan <moravanskyt@...>
Objet: [yamahacs80] New to the group, but maybe not to some
À: yamahacs80@yahoogroups.com
Date: mardi 3 Mars 2009, 20 h 04






Hello, I hate joining a group just to get a question answered or problem solved, so I'll try to stick around and be as helpful as I can be.

In addition to the other old synths and effetcs I've accumulated, I have a CS-80 here that I'm repairing.

It's got a weird problem and I wonder if anyone has seen this before. It plays normally as long as I don't pres any keys in the topmost octave.

I popped the hood and traced it down to the YM26700 D/A converter on the KAS board. Well, at least I think that's the problem. Here's what I measured:

pins 19-30 are getting the correct voltages for each key in the octave,
pins 13-18 have the correct voltages for the octaves (0.125 through 4),
pins 5-8 are reacting correcting for each key in the octave,
pins 9-11 are reacting correctly to indicate the octaves,

pins 31-38 (channels 1-8) output the correct voltages up and down the keyboard until I press keys in the upper octave. If I press a key up there, the voltage reading drops into the negative (i.e. -2.5v, 3.5v, etc).

Could there be anything outside the 26700 causing this behavior?

If not, are there any sources for a YM26700?

If not, who wants to buy a CS50 or 60 with me for parts?

Oh - I do happen to have a handful of lever switches, keys (white and black), some panel buttons w. bulbs, and the entire 4-bank 'memory' board that fits under the flip top panel, so I'm not coming here completely empty handed...

thanks,

Tom

















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[Non-text portions of this message have been removed]

Hi Tom,

welcome to this list, I´ve been missing you quite a bit on AH... :-).

Stephen

____________________________________________________________________

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  ----- Original Message ----- 
  From: tmoravan 
  To: yamahacs80@yahoogroups.com 
  Sent: Wednesday, March 04, 2009 2:04 AM
  Subject: [yamahacs80] New to the group, but maybe not to some


  Hello, I hate joining a group just to get a question answered or problem solved, so I'll try to stick around and be as helpful as I can be.

  In addition to the other old synths and effetcs I've accumulated, I have a CS-80 here that I'm repairing.

  It's got a weird problem and I wonder if anyone has seen this before. It plays normally as long as I don't pres any keys in the topmost octave.

  I popped the hood and traced it down to the YM26700 D/A converter on the KAS board. Well, at least I think that's the problem. Here's what I measured:

  pins 19-30 are getting the correct voltages for each key in the octave,
  pins 13-18 have the correct voltages for the octaves (0.125 through 4),
  pins 5-8 are reacting correcting for each key in the octave,
  pins 9-11 are reacting correctly to indicate the octaves,

  pins 31-38 (channels 1-8) output the correct voltages up and down the keyboard until I press keys in the upper octave. If I press a key up there, the voltage reading drops into the negative (i.e. -2.5v, 3.5v, etc).

  Could there be anything outside the 26700 causing this behavior?

  If not, are there any sources for a YM26700?

  If not, who wants to buy a CS50 or 60 with me for parts?

  Oh - I do happen to have a handful of lever switches, keys (white and black), some panel buttons w. bulbs, and the entire 4-bank 'memory' board that fits under the flip top panel, so I'm not coming here completely empty handed...

  thanks,

  Tom



  

[Non-text portions of this message have been removed]

--- In yamahacs80@yahoogroups.com, "Wavecomputer360" <wavecomputer360@...> wrote:
>
> Hi Tom,
> 
> welcome to this list, I´ve been missing you quite a bit on AH... :-).
> 
> Stephen
> 
> 

Thanks Stephen.  If AH is still mostly about buying/selling gear, discussions about TB-303's and clones, and analog vs digital debates, I think I'll stay away for another 5 years.  :-)


BTW - I've got a few tips/suggestions to try out with regards to my CS-80 problem and as soon as I'm home again I'll take a look and report back.  the problem may not be in the 26700 IC after all...

Hi Tom.
I had in the past the same problem:
The CMOS on KAS and SH boards.
P.S. you still have the oberheim 8 voice?