Yamaha CS80

That is great......


Now I have a question as I recieved 2 CS60 Voice Cards for parts
yesterday........for my CS80.

I have 2 voices in panel 2 that sound out of whack and I believe it is
to do with the Waveshape chip (IG00158) as it only affects the
waves saw and pulse....

Would the best advice be to use the new cards as is with the
"32degree" IG00153's or to attempt the exchanging of the waveshape
chip as it is soldered directly to the board.....

if so....can the IG00158 be socketed if i use a spare socket from
another chip of my spare boards on the reinstallation??, or does it
need to be against the pcb.....


for reference, I have the newer more stable  osc chips with the 
suggested mod which I did back in  the 90s....of course back then I
had no use for the older chips, and lost the instructions at the same
time....


Any suggestions before desoldering???


-----Original message-----
From: The Old Crowoldcrow@...
Date: Tue, 17 Mar 2009 22:39:13 -0600
To: yamahacs80@yahoogroups.com
Subject: [yamahacs80] VCO153 project in board test phase

Hey folks, its been a while, but I have this thing in testing right 
now. This is an equivalent circuit to the IG00153. This differs from 
my MOTM-style modular 153 oscillator in that it is strictly the VCO IC

with a ramp output, linear CV input, current bias input (FT) for
octave 
select and exponential modulation (vibrato) input. It can use the 
original M-board FET and charge pump capacitor, or those can be
removed 
and local ones installed. I made this mainly to see about replacing 
things at the chip level, but not relying on custom devices. It is 98%

SMT parts, with only 3 parts left through-hole for the moment (mainly
to 
swap things and see how the specs change). It no longer needs an input

offset trimmer, or external frequency compensation of the inputsumming

amp. The DIL-16 footprint in the middle of the board is used to
install 
it into an actual IG00153 socket. Generally it is low-profile enough
to 
fit between M boards (it does in my CS-50). It has internal
temperature 
compensation of the charge switch and comparator, making it much more 
stable than the original device. The charge pump core circuit runs on 
its own internal 10V reference supply.

Eventually I want to craft the entire M-board from standard circuits. 
The waveshaper is done (it is the one I made for the 153 module). The 
EGs are done. The filters are done. I know how to build the VCA, thats

next. In any case here is an image of the board, a bit larger than 
actual size. More later...

http://www.cs80.com/VCO153_pic.gif


Crow
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