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Do we have a list off all the errors in the calibration manual?
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I'm asking this question basically to see how people have approached the filter and VCA tuning discrepancies in the service manual.? I've read several different opinions on them, but have yet to find a consensus or a correct answer.? I've got two CS-80s here right now to experiment on.? One of them I probably calibrated somewhat wrong over a decade ago and could probably use a new calibration.??
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Here's the latest take:
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Thoughts?
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-Mike Borish
borishelectronics.com |
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Mike: For the CS-80, when referencing the Adjustment Procedure?document, below is what I have learned about the typos and inaccuracies on the filter and vca adjustment docs and how I do it. VCF - Complete Alignment - Page 11 ?Make sure to do the sustain level and attack adjustment procedures first. When doing the?adjustment, I use two trimmers at the same time and adjust the peak and gain pots simultaneously. Makes setting the?High Pass filter quick and easy. If you can't achieve the correct voltage settings (sometimes you can ALMOST get there, argh) then you have a bad chip. Good chips will easily hit the intended target level every time. Item 1.
The CP3 terminal reference is incorrect?and should be CP2. I use CP7 however which is electrically the same thing; it's just easier to get at the way I do it. The 4.3 Vp-p value is incorrect and is the zero-to-peak value. The correct value is double that and should be 8.6 V peak-to-peak to match the pictorial representation. Item 2.??The terminal reference of CP3 is incorrect and should be CP8. The 2.2 Vp-p value in the pictorial is correct. VCA - Page 15 Make sure you have a good ground reference for the scope on the card itself. If using a rack mounting ear, make sure the screw is good and tight (which should be done anyway). Item 2. VCA #2 Gain - As shown, but set both the BRILLIANCE and RESONANCE paddles on the main panel to the full forward (the low) position to achieve the correct wave shape. Item 4. Output Terminal - Rather than using a scope for adjusting the output VCA to 80,mVp-p,?use a good DMM and set it to dBm. Adjust the trimmer to a 28.3 mV RMS value. Much easier to do and more consistent between voices. Also, lately I've been replacing the voice card 2SC458 output transistor with KSC1815 parts as I've seen several go bad. Drop-in replacement with a lower noise figure. Yamaha went to the 1815's for the CS-70M cards, fwiw.? Scott Rodriguez 11/11/24 On Sun, Nov 10, 2024 at 11:40?PM mborish_2000 via <mborish_2000=[email protected]> wrote:
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开云体育Hello Mike, I have a CS-80 that repaired long, long time ago, more than 20 years.... I have the tech manual, but it is very far from me, now. to see it and go to the point. But I remember one thing that you can use. You are trying to calibrate a board that you have changed components, right?. So look for a pattern that repeats on boards that do not have suffered a modification and is ok. I suppose that having 16 OSCILLATORS, you could find some that are OK. I remember that some parameters are affected by the way you touch the keyboard.... so I build a simulator of the mechanism with relays (for replacing the switches) and 555 to simulate it in a predictable way. GOOD LUCK! Gustavo. On 2024-11-11 10:20 AM, Scott Rodriguez
via groups.io wrote:
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Hi Mike,
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MFox here. :)
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Just a few additional words. I was really struggeling with the resonance, it always collapsed when I dialed it to the specs, but not on every voiceboard, some made it collapse earlier some later. Joachim Wilson (also a member of this group) was able to push it further. In the end I decided to go with the of the CS60 procedure for the filter and maybe adjust it a little more towards the CS80 specs until it worked fine on every voice board. Not sure what sound nuance I am missing, but the good thing is it still sounds like a CS80. ;)
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Not sure if Greg is also a member of the group, but he was also seeing this during his calibration and tried to figure out a solution. He was telling me, that he calibrated the HPF to 4.3V and then cycled back to the same note, rised the brilliance level all the way up and then back down to the center. There is a level loss, but it sounded in the end right to him. Maybe you can try out that approach.
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Michael |
开云体育Hey Michael and everyone, I am indeed part of the group and thanks for chiming me in :)As Michael stated, the resonance seems to “collapse” when you adjust too far, but iirc I noticed if you raise the brilliance paddle up to top then back to centre you can “regain” the level and continue from where you had it collapse, allowing it to go further up in p-p voltage. ?Hope that makes sense! ? The one observation I noticed doing it this way however is the relationship of this calibration to the brilliance paddle movement. For example once calibrated to a higher p-p voltage, raising the paddle from middle to top then back to middle keeps the maximum resonance centred—however lowering the paddle to bottom and back to middle the balance point becomes offset and collapsed(the maximum slightly higher than the detent point). ?It makes me think that what we are actually trying to achieve here with this calibration is a bipolar balance so moving the paddle to either extreme and back to the detent we can keep the maximum level at the detent position if that makes sense. ?Not sure what p-p voltage that would be in certain CS80’s, maybe closer to the CS60 values as Michael was experimenting with, but just my own theory. Anyway… Someone out there must be holding some secret Yamaha documents about this calibration between revisions though, I find it too strange how this particular calibration was so off in the CS80 I had here. Greg C.
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