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" > >  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@... > 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] >
Message
Re: Here's a strange tuning issue...
2010-01-24 by Quazimodo