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CS-80: make a plan for a servicing
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Congratulations! It's a wonderful beast. Just a quick comment. I would approach things differently. I would hunt down and fix just the known problems, and any more I did find after it got it mostly working. Then calibrate it fully. Only then would I consider any sort of upgrade or changing out of parts. My reasons are "if it ain't broke, don't fix it" and also we only have so much time and $ in this world; I'd rather spend it playing the beast than looking at a pile of parts and hoping that someday I can play after it's been hardened/upgraded to survive the "Next" 50 years.
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Cheers, Kyle On January 9, 2019 at 5:24 AM "pepeisnotadog@... [yamahacs80]" <yamahacs80@...> wrote: ? |
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Hi
Am 09.01.2019 um 15:38 schrieb Kyle Jarger jkjelec@... [yamahacs80]: I'd like to I agree. But I understand that Mark wants a general refurbishing too, to make the synth future-proof. Nevertheless he should first fix all problems. The Refurbishing can be done after the problem solvening, when he can be sure, that there are no issues. The basic principle is here: don't change two things at the same time. If you would do so, you will have serious troubles to find which of the changes caused a problem. As a concrete example: if you have ripple on a supply voltage, the don't do a complete recapping. Just replace the faulty capacitor and check whether the ripple disappeard. After that you may do a complete recapping. Florian -- |
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Well stated Florian!
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On January 9, 2019 at 9:48 AM "Florian Anwander fanwander@... [yamahacs80]" <yamahacs80@...> wrote: |
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Scott Rodriguez
>> In short, it’s a moral duty to bring it back to life. Yes it is. >> 1) start with power supply, replace old electrolytics cap. Are there any other parts that you recommend to change? Because my unit was in the same situation, and because I couldn't find drop-in replacements, I removed and reformed the big electrolytics over a 4 day period and got them down to a leakage rate of 8 uA, better than many new ones. I wouldn't just fire them up after sitting so long, I'd reform the layer. I'd replace all the other electrolytics (use high ripple spec on the rectifiers and low impedance spec on the decouplers), the power transistors (the 4 big ones and the 6 little ones) and the two 4558 op amps.? 2) go to the five boards (KAS, SH, TKC and the two TSB) under the keyboard: - replace all the electrolytics? ?Yes Go to 25 volt units instead of the 16 volt units installed, especially on the OE1, OE2, and PRA boards in the rack - replace all the CMOS (maybe installing new sockets) Yes, using the expensive sockets with built-in decoupling caps - add decopuling cap for the IC (based on your experience is it better to buy “built-in sockets with caps” or solder the caps separately?)?As above, but the built-in socket type are for the 4000-series chips only. ?Given that I am still defining the plan, do you also recommend these operations (or just some of them) for these five boards? - replace old op amp?Yes, for those items not in the audio signal chain, and any 4558's that are in the audio signal chain. - replace old bjt? Do not do this. You risk losing the synth's character - replace all the ceramic disc capacitor (with dipped ceramic) No need to do this unless they are physically damaged or have corrosion on the leads. - replace all the "famous" tantalum capacitor (with polystyrene or polypropylene or aluminum electrolytics, same value obviously)? There's only one or two in the synth, but sure, replace those too. Use a heat sink on the leads when doing so to prevent loss of capacitance, tant's don't like heat. - replace all the mylar capacitor with polypropylene or polystyrene Absolutely not, you risk losing character bit time, especially on the filters. Only replace if you have a bad one, and then try to find an old good one. Take my advice from experience. - replace the few old trimmers That's a lot of work and expense, I'd only do it as required, not as a course of practice. ?Going to the boards behind the keyboard.. Regarding all M Boards: -?????replace all the electrolytics? Yes. Use audio grade on the filters and in the signal path, low impedance for the large decouplers -? ? ??replace all the old trimmers too? As above, only as required. Regarding the two KBC Boards: -??????????replace all the electrolytics? Yes. -??????????replace all the CMOS (maybe installing new sockets and decopuling cap for the IC (like the boards under the keys)?Yes to both. There is some decoupling on here already, but the additional ones at the chip can't hurt. Of note: ?Be ready to find some dead ig00151 amplifiers on the M boards if you're not getting a signals. Mine (which was a basket case, admittedly) needed (45) ig00151 chips in the end. Yes, that's 45 chips, but that's not normal. Still, I had those along with one dead oscillator, one dead wsc, two dead filters, and one dead filter envelope chip. The only one on the M boards that didn't have a dead one was the amplifier envelope chips. You have to mentally either commit to owning a truly restored vintage CS80 including all the time and expense that entails, or give it to someone else that will. I made the decision to commit and have not regretted it once, quite the contrary, it's a stunningly beautiful instrument to play when hitting on all cylinders. Also, be aware that the 151's can 'sort of' work, that is, they pass a signal, but are not controlling the envelopes properly or you can't get a full output level as you should. When everything is working properly, you should be able to calibrate the M boards per the manual. If you can 'almost' get a setting on a trimmer but run out of travel, something's wrong (and it could be the trimmer, have seen that too, there's a couple of failure modes for those). There's a lot of errors in the manual. A major one of note I just spent a lot of time with is the VCA levels for the last two output chips on the M boards. The adjustment procedure calls out 400 mV and 80 mV respectively. That cannot possible be correct, you will have lots of 50/60 cycle hum in the output and a lot of noise in the OE effect section. I added led's on the M boards using the key trigger signal along with a regular diode and resistor. That mod was invaluable. I also added little hard point loops on the six main test points on the boards for grabbing them with a spring-loaded scope hook probe. WELL worth the effort. Best of luck, Scott synthRodriguez
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Scott Rodriguez
As a follow-on, I do understand the "don't fix it if it ain't broke" mentality, and have certainly gravitated more toward that position over the years, but in the case of the CS-80 it's a beast, and a beast I don't want to crack open any more than I have to. Toward that end, I wanted to make it as solid as possible so I took the position of all-new logic chips with decoupling sockets, all-new electrolytics and a total power supply rebuild. The only two 4000-series chips I couldn't source new were the (2) 4006 chips on the KBC boards, and even those now have late-80's chips with decoupling sockets. Haven't had a moment's problem with any of it, as hoped and expected. Outside the copious M-board problems, I had a one bad HA1452 and a few bad 2SK30A's on the OE1 card (lots of bad crackling in the outputs). Also had lot's of bad violet Matsushita capacitors with corroded leads that were about to take a serious toll throughout the synth. I did a swap?due to corrosion?on (2) M-boards using spare CS-50 cards I had, but that was it. Scott - synthRodriguez On Wed, Jan 9, 2019 at 1:54 PM Scott Rodriguez <synthrodriguez@...> wrote:
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开云体育It’s not difficult to obtain an obscene amount of?ig00151 ICs cheaply, if you are willing to kill off certain electone organ models. At least one model also has the VCFs (but not many). A kind soul in Montreal pointed me to this solution via this list many years ago….Whatever happened to Old Crow’s project where he was actually making new?replacement?ICs (or at least M boards) for the CS series? Does anyone know? Also - I agree about not replacing things that do not need to be replaced. But are there any parts that are time bombs that could potentially take out huge sections of a CS? I have a CS that got blown up in a recording studio years ago. Something went wrong and some diodes in the PSU went and then took out a lot of ICs on my M-boards along with them. I have this synth working now, and it has all new caps in the PSU and some new diodes, but I’m nervous about what might do similar damage next time... best, DT |
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When I wrote 'filter types' above I meant the filter envelope type sliders (IL, AL, A, D, R) should be fully down.
Also note that bobbins CP2 and CP7 on the M cards are the same thing (they are connected through the wire harness) likewise CP3 and CP8 are connected and carry the same signal. You have to read either CP2 or CP7 when setting up the HPF. The manual says CP3, that is incorrect for the HPF, but is correct for the LPF.? If you're trying to read levels at CP3 for the HPF, you're never get the right reading, it's a typo error in the manual. |
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Mark:
I was in a rush and for that voltage backward, apologies. I deleted that message and corrected my error below. Thanks for calling me out on that, the manual voltages are correct. When calibrating, the Brilliance lever should be centered and the Resonance should be at maximum (pulled fully toward you). All related sliders (filter types, initial level etc) should be at 0 or fully low. When setting up the HPF, the two LFP sliders next to it on the panel (cutoff and resonance) should be fully up. Conversley, when setting up the LPF, the two HPF sliders next to it should be fully down. When setting up either filter, resonance for that filter should be fully up.? For HPF, the voltage at the FH terminal on the R6 board should be +4.0 VDC . Once you set this exactly , measure the voltage at the wiper terminal on the filter slider. You can now use the wiper voltage to measure when setting up each voice. Mine is 4.625 VDC at the wiper when 4.0 on the R6 board. Do the same thing for the 3.3 VDC setting at the FL terminal for the low pass filter slider. My LPF wiper measures 3.925 VDC. For the HPF, I set up max amplitude at 7.6 V p-p per the CS-50 setup sheet, not 4.3 VDC as on the CS-80 setup sheet which I believe is incorrect. The 4.3 setting just doesn't give you enough resonance. There's a blog on the web that says 8.4 V p-p is correct, but I found that too high. 7.6 is nice, 4.3 is anemic. Read the signal using the oscilloscope at the CP7 terminal on the M card for HPF and at the CP8 terminal for the LPF. It is very important to make sure the wiper voltage is set exactly when adjusting each voice. If your pot is dirty and jumps around, even a little, take the time to tear it down and clean it. You will never have a CS-80 with even sounding resonance between voices if you don't have the wiper voltage the same exactly for each one, shoot for ± 0.020 VDC. |
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Scott Rodriguez
So, nothing at all coming out of Pin 7 on the 00153's?
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