Yamaha CS80

Hi David:
Thanks for your words.
I know that an oscilloscope is what I need, but I meter some pins
that supossedly output steady ones or zeros, not pulses, and they
don't work. Appart form that the YM26700 have a dark (carbon like)
colour, that's very suspicius :(
About the Kenton kit, as I said before, I alredy own it, so it won't
cost me any extra money, I don't think that selling it is a choice.
The PAiA MIDI to CV is really cheap, and I bought a used one for 30 US
dollars incluiding an overseas shipping (I could use it to drive
other synths anyway).
And finally here in Argentina, old synth are very rare and expensive.
A CS-50 trades here but about 650 US dollars (I don't gonna sell it).
I think that I'm going to make sure if the Yamaha ICs are wrong or 
not, then
if they are wrong I'm going to use the PAiA to drive the synth.

Sebastian




--- In yamahacs80@yahoogroups.com, David Rogoff <david@...> wrote:
>
> Hi Sebastian!
> 
> Welcome to the group.  I'm not sure what's wrong with your CS-50, 
but I 
> don't think you have a chance of tracing it without an 
oscilloscope.  
> Lot's of the key data is time-multiplexed, so a meter won't be good 
> enough to see what is going on.  I picked up an old 10 MHz 'scope 
for 
> about $50, which was good enough for anything in the Yamaha.
> 
> As far as finding spare KAS & DAC chips: good luck!  As I posted, 
> someone has been selling off parts of a CS80 on eBay, but so far 
hasn't 
> put up any of the boards with the custom Yamaha chips.   Actually, 
> CS-50s are good sources of spare parts for CS80s, but that won't 
help you...
> 
> I'd actually bet it's not the Yamaha chips, and it's probably some 
of 
> the CMOS chips.  Anyway, if you pick up a 'scope, the service 
manual has 
> enough detail of the waveforms to see what they should be.
> 
> If you would be happy with the Kenton and the Paia, go ahead, but I 
> would be hesitant to put so much money into the MIDI kits, which, 
at 
> least in the US, cost more than the CS-50.
> 
> Keep us up to date on your repairs & upgrades!
> 
>  David
> 
> sebastian_cordoves wrote:
> > Hi all:
> > I'm Sebastian Cordoves from Argentina, my native language is 
spanish,
> > please forgive my poor english.
> > I'm a recording technician, and teach music production for living.
> > My wife sings, togheter we have a electro-pop band. 
> > I own some analogue synths, and know a bit about electronics, so 
I do
> > my own repairing (everytime I could).
> > I bought a Yamaha CS-50 about 6 years ago, it worked well for 
about a
> > year, but then it broke up. I bought a Kenton MIDI retrofit, but 
never
> > installed it because it came a few days before the synth stopped 
> > working.
> > For various reasons I put the synth aside and only about a year 
ago
> > started trying to repair it.
> > The problem is the KAS, and I am almost sure that is one of the 
Yamaha
> > custom chips (YM26600 or YM26700). I don't have an oscilloscope, 
so
> > I do some metering with a multimeter and some of the pins are 
outputting
> > what I think is right data but others are dead. I have the 
schematics
> > of the CS-50 (Courtesy of Kenton), I'm in the process of scanning 
them,
> > I can post them later.
> > At the moment I'm driving one voice of the synth with the CV/Gate 
out
> > of my Novation BassStation Rack. I'm planning to buy a PAiA MIDI 
to CV
> > interface to drive the 4 voices, and install the Kenton retrofit 
to
> > control cutoff and other parameters.
> > But it will be great if I found the Yamaha IC's and remplace them.
> > Does anybody know where can I find those chips or even an entire 
KAS?
> > I've looked in e-bay and over the internet with no luck.
> > Thanks in advance for your help.
> >
> >   
> 
> 
> 
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