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Re: Wah-Wah
Hi Tom,
I just posted a redrawn diagram to get a better overview of the effects order. Since, for some reason, the resolution is reduced after the file transfer, I put a copy here too : What you're trying to do was originally planned by Yamaha. It is visible on page 66 of the Service Manual, where the WAH alone is drawn but was carefully struck out. On the next diagram, I have reconstructed what the initial design might have been : Note that this only an hypothesis and I do not pretend that it works. Anyway, that gives the idea. The reason why Yamaha chose not to do it is not clear. Perhaps the PRA board was already full ? As for controlling the brilliance, that would require an other design. Joachim |
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Re: Wah-Wah
Another Question about the exp wha circuit: none of you have audio or video where you can hear this effect? On my cs 80, with the pedal at full volume (full down) , you will hear the sound of the bandpass filter. He is normal? See my cs80 on this video, I play the pedal up & down vithout touch the keyboard:? Thanks Tommaso
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Re: Wah-Wah
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On Apr 20, 2017, at 11:58 AM, noddyspuncture@... [yamahacs80] <yamahacs80@...> wrote:
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Re: Wah-Wah
开云体育Hi Tom! ? Quick note since I’m at work.? I’m looking at the big, fold-out schematic at the PRA EXP WAH Circuit all the way at the top right.? The foot pedal voltage comes in on EI(52) and buffered by IC3. The output goes through LEDs PH1 and PH2 that shine on internal photocells for the volume control.? It also goes to PH3, over to the left, to control the wah (nothing to do with the brilliance or VCFs) The catch is that, since they’re in series, you can control wah without volume in the LED/photocell modules.?? You could just use a DSDP switch to bypass the photocell pins on PH1 and PH2 so the pedal doesn’t control the volume.? It might mess with the level so it could need a couple of resistors in series with the bypass path so the volume is the same. ? David On Apr 20, 2017, at 8:40 AM, noddyspuncture@... [yamahacs80] <yamahacs80@...> wrote:
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Wah-Wah
Hi folks, Not been here for a long time... but I thought I'd make a quick post. I've been playing the 80's a lot recently... and have gotten into altering the Brilliance fader during play. It's quite tricky to get a free hand in sync so I thought I'd look at the "wah" function on the expression pedal. First thing that struck me was that along with "wah" you also must have volume. Not what I'd like. I'd like the volume to be set and just open and close the "Brillinace". Second thing was that I thought I might be able to "modify" to get just "wah"... but looking at the schematic I cannot fathom how the "wah" function works. It doesn't seem to be a direct replacement for the Brilliance lever...? Could anyone please shed some light on it please...? So, apart from disconnecting the Brill pot's wiper and putting it to a foot pedal sweeping between +/-15 volts - which was an idea I had - can anyone think of a quick way of getting that function...? Cheers, Tom |
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Re: One more thing...
I'm sorry I can't provide any further details about where the grounds join together or join back to the grounds from the PSU; I just don't remember. ?One detail I can provide is that it was power rails measured with respect ?to the metal chassis that would change depending on what keys were played, so for example that +11V you are measuring would move around depending on what key was last pressed. That 2K ohms measured from the Mcard Gnd to the +/- 15 V ground sounds fishy to me, but you'll want to confirm of this is correct/expected before you change/add any connections, lest you cause even more damage. jkjelec
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Re: One more thing...
开云体育I’m keen to know where the grounds should be linked. I’m seeing the M card
ground is 0.3 ohm with respect to the logic power ground, but around 2k to the
+/-15V ground. I’m guessing that shouldn’t be the case?
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Lucid.
? From: mailto:yamahacs80@...
Sent: Wednesday, March 15, 2017 4:03 AM
Subject: [yamahacs80] One more thing... ?
?
Hi Lucid Sound, I
remember that in the case i mentioned, some of the voltages I measured would
change unexpectedly when I played up and down the keyboard, thus giving me the
clue that the analog and digital systems had become "floating" relative to each
other. Kyle jkjelec |
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Re: CS80 Strange Behaviour
I'd check if all the intended ground connections are intact. ?I've seen units where the +6.5/-8.5 (whatever it is LOL) volts, (or the other rail) become "decoupled" from each other when they lose their common ground connection. ?This could be due to a broken wire near a ring terminal, for example a screw on the wood chassis that connects these system grounds together. jkjelec On March 14, 2017 at 6:09 PM "'LucidSound' lucidsound@... [yamahacs80]" <yamahacs80@...> wrote: |
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CS80 Strange Behaviour
开云体育Today I had a CS80 in for a service. Basically most of the voices were
working, but a couple were dead and there was the usual problem with unequal
volume and filter cutoff. Nothing too drastic then. I found two dead oscillator
chips, but have some spares, so that fixed that. So, after several hours work,
all of panel 1 was sounding pretty decent.
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Then the audio just quit. No output. Nothing. I checked the fuses and power
supplies, all appear good. Taking an oscillator card, I can see a key voltage on
Pin 2 of the VCO chip which changes as I play the keyboard, yet no waveform
output. Take another card, same thing.
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So, how about the white noise? It comes into the M card, but doesn’t leave
the filters.
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Next thing – I find that the ground on the M card is referenced to GND2. If
I meter between the GND1 and GND2, I see around 2k ohms. Confused???
So am I. So if I measure the 15V rail at the VCO chip, I see around +11V if I
take the negative lead of the meter to the metal chassis.
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Where to go from here? Any ideas welcome.
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MTIA
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Lucid.
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CS80 schematic project
开云体育Hi all. As many of you know who’ve repaired CS-80s (and related), the Yamaha schematics and board layouts are full of errors. ?In addition, in my work in replacing parts on various boards, it’s become a huge pain that most resistors and capacitors don’t have any reference designators (e.g. R21, C7). ?This makes it very difficult to make parts list and keep track of what’s been replaced or even refer to components when doing repairs. To start with, I’ve made up my own marked up versions of the KAS and M-Board schematics and board layouts with all parts given reference designators. ?I’ve put copies of the M-card files in this file group: These are very helpful but it would be much better to re-create the schematics in a real EDA tool. This would allow cleaner corrections, generation of parts lists, and possibly even creation of board layout files to create new cards with better layout and pad locations for modern parts. ?I’d at least want to create the basic pad and silkscreen layers to help with debugging boards by having labels for all the parts. The website even has direct links to PBC manufacturers if we wanted to create actual boards. ?I think it can even do some Spice simulations. I looked around at various tools and found a great looking website at . ?It’s got schematic and board layout tools that are very easy to use and runs on any computer or tablet since it runs in a browser. ?I’ve started working on the M-Board schematic and was hoping some other folks would be interested in helping out completing the schematic based on my marked-up schematic PDF. ?I put a PDF of how far I’ve gotten in the folder listed above (most reference designators are wrong). I’ve also made a public copy of the easyeda project here:? So, who is interested in this and willing to help out. ?Although the website is fairly easy to use, it would still be extremely beneficial for people involved to have some knowledge/experience in creating schematics. ?Take a look and let me know! Thanks, ?David |
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New file uploaded to yamahacs80
Hello,
This email message is a notification to let you know that a file has been uploaded to the Files area of the yamahacs80 group. File : /EDA Project/easyeda M-board schematic.pdf Uploaded by : unfrostedpoptart <david@...> Description : You can access this file at the URL: To learn more about file sharing for your group, please visit: Regards, unfrostedpoptart <david@...> |
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New file uploaded to yamahacs80
Hello,
This email message is a notification to let you know that a file has been uploaded to the Files area of the yamahacs80 group. File : /EDA Project/m-board layout.png Uploaded by : unfrostedpoptart <david@...> Description : marked up layout You can access this file at the URL: To learn more about file sharing for your group, please visit: Regards, unfrostedpoptart <david@...> |
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Re: Some CS news
开云体育Hello DavidOn 05.03.17 06:27 , David Rogoff david@... [yamahacs80] wrote: ?Get to all the forums and maillists, and you will find them filled with postings about it. Florian |
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Some CS news
开云体育Hi all.Just passing on a couple of articles I’ve seen lately that should be of interest. First, an SY-1 on eBay. Currently $400 with no bids and $550 buy-it-now.? I’m tempted. Here’s someone who’s apparently working on a rack-mount CS80. ?It’s supposed to be available as a kit or fully built. Anyone know more about this? Crow’s GX-1 filter clone. CS-80 Ring-Mod clone module. Enjoy! ?David |
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Re: Dead CS80 - finding a short
Happy End!?
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Re: Dead CS80 - finding a short
开云体育Great news!FYI, when I had similar problems with TSB cap shorts, it was confusing because it didn’t show up as a short to ground. ?Instead, the short was between +15 and and -15. ?Something about the load on the +15 causing too much current - and blowing the fuse - on the -15. I don’t remember the details - I think I posted about it. ?Took some time to figure out. ?David
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