Hey Kent, many thanks for the info!
I called it 'strange' as it's the first time I have come across this in all my years tuning the beasty. Hope it's not a sign of things to come!?
Please could you expalain tightening up the resistors 1,2,3 and 4..?
And the VR's themselves..?
Do you mean change their values?
Thanks again,
TOM
--- In yamahacs80@yahoogroups.com, "kent_spong" <kent_spong@...> wrote:
>
> Hiya,
>
> This is not a strange tuning issue at all. Your VCO's over time will lose there liniarity, so you will need to tighten u the R1 R2 R3 and R4 resistors and VR's to compensate this on the cards with the problem or replace the VCO's them selves ( yeah right .
>
> The alternative to this is to use the Kentuky Windage tuneing method used on the ser no 1000 to 1150 models. What you do is adjust the scale pot for lowest C so that the tune goes out in the 4" and 2" end on those cards.
>
> --- In yamahacs80@yahoogroups.com, "Quazimodo" <noddyspuncture@> wrote:
> >
> > Thanks for your replies guys,
> >
> > Laurie, I have a 'feeling' though that this might be a fault. It is quite a severe symtom affecting only two cards (one more than the other) I had to do quite an adjustment to VR2 (the octave) to bring the lower octave 'in' in card 6. And I use a scope where you can actaully see the waves 'beating'. I adjust until they are virtually motionless, so it should be spot on. If it was a heat issue wouldn't there be more voices reacting in a similar way?
> >
> > Anyway there is one other thing. Have you noticed - and it's probably easier with a scope as you can ∗see∗ it happening - that with VR3 (the multi-turn '2 tune pot) you can actually tune though the 'correct' pitch about 5 or 6 times from one end to the other? It caught me out a few times as only one of the settings actually works with the rest of the tuning set-up. If you pick the wrong one - it'll all look and sound right but you'll never get the 4/8/16 feet in.
> >
> > I wonder if there is a trick to knowing exactly which one (of the 5 or 6 posssibles) it should be? They must have had something at the factory because you can waste a hell of a lot of time searching it out! I assume they are 'harmonics' of the correct waveform that are being caught there!?
> >
> > Cheers,
> > TOM
> >
> >
> >
> > --- In yamahacs80@yahoogroups.com, "Laurie Curry" <laurie@> wrote:
> > >
> > >
> > > I always tune mine "hot"....I let the CS80 warm up to temperature with
> > > the lid down and my "half"
> > >
> > > Â 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...
> > >
> > > Â 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/ 8Â 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@
> > > 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
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > [Non-text portions of this message have been removed]
> > >
> >
>