Yamaha CS80

I always tune mine "hot"....I let the CS80 warm up to temperature with
the lid down and my "half"

 case cover on...all screws are out for lid and M board
Carriage...... master tunes, detune II and fine tunes at center
"0'..both banks set to 2 foot .. after a couple hours in warmup,  I
open the lid,  cover the top and back of the M board carriage with a
folded towel to keep heat in, and I raise the carriage....  I cover
the keybed with a towel to keep any foreign objects from coming in
contact or falling into the lower half of the CS80....


 With the Mix setting 100% to bank  II, I start adjusting.....

(to each your own......I am one of those who touches the foil side
lightly behind the blue pot to find oscillators....as shown to me from
the yamaha tech in the 80's)

the mini blue pot is the adjustment for tuning the 2 foot..... the
first larger trim is the "octave calibration"...

I play the low range osc1  into a tuner and mark its  sharpnes or
flatness... then I search for osc 1 again using the upper
octaves.....If they are both equally sharp or flat I do not adjust
this pot...

I only adjust the little blue one.....counter clockwise sharpens the
pitch, clockwise flattens.....

You want to use an insulated scewdriver as a metal one will alter the
pitch you are reading as you adjust....

on the other hand if the reading of the upper is sharper than the
lower, you need to turn the larger pot clockwise, and counter
clockwise if the upper is flatter than the lower octave....once you
are sure the upper and lower octaves are at the same place in
shap/flat..... tune the osc into tune with the little blue one...

after bank 2 is done for all 8, adjust mix 1 in the same way.......


at this point once the  2 foot is in tune, I usually close the CS80
up and let it sit for an hour to 'rewarm" itsself....upon returning I
recheck the 2 foot with the lid downin both banks to see if everything
has stayed in the right place... taking note of which mix may need
further tweaking...


once I raise the lid I repeat the covering with towels and raise the
carriage....

I will repeat the 2 foot process if there was any change searching for
the bad osc...

 If alls good , 4 foot on bank II using the second large trim pot
from top.... (I use the low range from this point on) tuning the
oscillators into pitch.....

You will notice thet the trims are easier to adjust in the
lower footage as they arent as touchy as the 2 foot trims...once 4
foot is done in both banks move to 8' and finally 16'.....


Close her up and play her for a while........ should sound sweet...to
the ears...


I experienced results like yours between 16/ 8  before too after a
sure tuning, but I found it was because the osc cards had cooled off
while I was adjusting....and when It rewarmed, the spread on 2 went
out so slightly it wasobvious in the lower octaves...


-----Original message-----
From: "Quazimodo" noddyspuncture@hotmail.com
Date: Sat, 23 Jan 2010 14:14:14 -0700
To: yamahacs80@yahoogroups.com
Subject: [yamahacs80] Here's a strange tuning issue...

This is a strange symptom - wonder if any tech's here might have come
across this one before..?

Today I tuned a CS80 - sinewaves on CD, CD player and CS80 into
Oscilloscope. Everything seemed to tune up great, visually and audio
wise. However when I closed the lid to play her - I noticed a couple
of notes (in the lower octaves) were quite flat. I investigated and
voices 5 and 6 on channel I were the culprits. Note, I had switched
footages to 16' and 8' (where I normally play) and this is where the
problem revealed itself.

I went back to 'tweak again' but I noticed that when adjusting the
first two settings as written in the manual (the keyboard 'spread'
adjustment) that this is done onthe 2' footage setting. When I went
back to that 2' footage, everything was fine again. It was all in tune
and perfectly set.

It is when I switch away, down to the footages I use most often 16'
and 8' that the problem arises.

Next I tried something - just using my ears I 'tweaked' the second pot
down on the culprit cards, under the fine trimmer, the one you adjust
in connection with the fine one, until those flat low notes sounded in
tune. This is totally workable and she plays beautifully down on the
16' and 8' settings, but now when I go to higher footages then those
same notes are miles out. Obviously something isn't quite right here.
What would cause the 'keyboard spread' to vary between footages?

Obviously, once set at 2' it should be correct for all footages,
otherwise there would be a seperate 'spread' adjustment for each. So I
have in effect 'botched' it!! Haha!

Please, does anyone know where I should start investigating this
wierdfault?

Hope someone can help
Cheers
TOM










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