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How to switch the polarity of an ordinary sustain pedal


gangsu

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I haven't got a clue. I thought I could just switch the wires around. No. That made no difference at all.

 

This can't be too difficult, could somebody please walk me through it? :blush:

 

First time playing with solder here. Kind of fun but I'd really like to get this right.

 

Thanks!

 

- looking for a "normally open" connection here.

http://stashbox.org/772132/circuitboard.jpg

 

 

"........! Try to make It..REAL! compared to what? ! ! ! " - BOPBEEPER
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If the ordinary sustain pedal is just a switch, it has no 'polarity'. All it does is to interrupt the signal. Reversing the wires going to the switch doesn't do anything about polarity. If it is just a pot, the same is basically true. What do you need to change?

"I believe that entertainment can aspire to be art, and can become art, but if you set out to make art you're an idiot."

 

Steve Martin

 

Show business: we're all here because we're not all there.

 

 

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There are some pedals made where there is an additional switch that changes what is commonly called "polarity," which is an incorrect naming by electronic standards.

 

Others have the capability of changing by moving wires on the pedal switch itself. That type of pedal has a double position switch (meaning that there is a normally open contact, a center contact, and a normally closed contact. However, the circuit board shown does not have that ability.

 

The Roland, Kawaii, or Yamaha standard pedal is "normally closed," and the Kurzweil standard pedal is "normally open." From a quick search, it appears that Casios have been made using each standard, and are not all the same.

 

"Normally closed" means that there is an electrical connection between te two wires when the pedal has not been pressed; and "normally open" means that there is no connection when the pedal has not been pressed. (when pressed, the opposite is true in each case.)

 

I'm not sure which type the Promega pedal is - because the instrument senses what type is connected and sets its internal logic accordingly (Kurzweil does this same thing, at least on all later instruments, although the second pedal on a K2000 does not, based on personal experience). Based on the difficulty you are having, apparantly this particular Promega pedal is normally closed.

 

Your best bet is to locate either a Yamaha type pedal (I say Yamaha because it is probably the type that is easiest to locate from the sheer volume of them sold), or else buy one of the ones that can be switched (if I were going to buy one, I'd by the universal type, since I might get a different board before I wore the pedal out).

 

 

 

 

Howard Grand|Hamm SK1-73|Kurz PC2|PC2X|PC3|PC3X|PC361; QSC K10's

HP DAW|Epi Les Paul & LP 5-str bass|iPad mini2

"Now faith is the substance of things hoped for, the evidence of things not seen."

Jim

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Sustain pedals are cheap, even decent ones. Many of us like the M-Audio SP-2.

"I'm so crazy, I don't know this is impossible! Hoo hoo!" - Daffy Duck

 

"The good news is that once you start piano you never have to worry about getting laid again. More time to practice!" - MOI

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You need a single pole double throw (SPDT) switch to toggle polarity. SPDT has normal close and normal open.

 

Your pic shows a single pole single throw switch. SPST has either normal close or normal open, but not both. You're out of luck.

 

I have a Roland sustain pedal with SPDT that I rewired.

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If the difference is that the switch needs to be the opposite of what it is... either normally open or normally closed, it is easy enough to check which you have, and equally easy to change the switch for the other type. The question is, is it worth it? Wouldn't a used pedal be only about $15?

"I believe that entertainment can aspire to be art, and can become art, but if you set out to make art you're an idiot."

 

Steve Martin

 

Show business: we're all here because we're not all there.

 

 

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Hey, sorry I didn't know that polarity was the wrong term. Thanks for the explanation. Too bad this circuit doesn't have the opposite contact. I opened it up not knowing what to expect and not understanding what I'm seeing.

 

This pedal also works with a Yamaha P120, so it's a closed circuit at rest. The casio is the opposite.

 

We'll buy the SP-2 if I can't do anything with this one.

 

This pedal's not being used and there's nothing wrong with it. I'd rather keep the change and learn something in the meantime.

"........! Try to make It..REAL! compared to what? ! ! ! " - BOPBEEPER
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I agree, it looks like you can't make this pedal work.

 

I'm with Joe on this one. M-audio pedals are sold at Best Buy and have the additional 'polarity' switch on the bottom. They are about $20 and work great. I have a couple in my bag just in case.

 

I started to carry them when I was at a blues competition and the backline kb had no sustain pedal. They asked me if I had one but mine was the opposite polarity. Lesson learned.

 

Pete

 

"all generalizations are false" ~Mark Twain

 

Kurzweil K2000, ME-1 and (2)PC3, Casio PX-350 AND PX-360, EV sXa 360

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ok, lesson learned. I can't envision walking into Circuit City and trying to describe what I need in order to make this work. I doubt they'd have it anyway.

 

Thanks all. :thu:

"........! Try to make It..REAL! compared to what? ! ! ! " - BOPBEEPER
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ok, lesson learned. I can't envision walking into Circuit City and trying to describe what I need in order to make this work. I doubt they'd have it anyway.

 

Thanks all. :thu:

 

I doubt they'd have it.

 

Didn't Circuit City go belly-up a few months back?

 

Well... the brick & morter stores anyway. KLONK

 

 

"Music expresses that which cannot be put into words and that which cannot remain silent." - Victor Hugo
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Son of a gun, I didn't even notice that Circuit City had disappeared. You're right, they're no longer in the phone book. Darn, it might have been fun asking for an SPDT switch (that will fit inside a sustain pedal). :idea::freak::)

 

I'm sooooo disappointed, though. It's not the money! It's the discovery I was into. Sometime I'd like to hear the whole story on how keyboards interpret the idea of sustain - full sustain, partial sustain, continuous sustain.... like what's really going on? You don't have to answer that. :D

"........! Try to make It..REAL! compared to what? ! ! ! " - BOPBEEPER
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Hi Sue. :)

 

Y'know? The sustain switch is just a momentary on (or momentary off) switch.

 

Or it is for most keyboards.

 

I am not quite certain how Yamaha, and others, implement partial sustain. I do know there's another contact point because the 1/4" plug is Tip-Ring-Sleeve (TRS), like the kind you find with stereo headphones and such.

 

But I'm not quite sure if it's still a switch or a potentiometer in the pedal that they are using. Kurzweil doesn't have partial sustain and the last Yamaha synth I owned was a DX7.

 

I hope you are doing well, Sue.

 

 

"Music expresses that which cannot be put into words and that which cannot remain silent." - Victor Hugo
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Hey Tom, I'm doing well. More work than I can handle. That's why I distract myself with this kind of thing.

 

Yeah, I get the switch concept and looping samples to sustain the sound. I don't like switch pedals in general but given no choice I'd probably carry the little coaster sized square thing rather than a piano style pedal that just takes up more space in the bag.

 

I wonder about half sustain. Is something cut from the sound? Maybe stereo becomes temporarily mono? Who knows. Or maybe what we think sounds like partial sustain is just a ton of reverb or some other effect.

 

well, thanks for appearing to wonder yourself. :) I better sign out and get on with the day.

"........! Try to make It..REAL! compared to what? ! ! ! " - BOPBEEPER
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But I'm not quite sure if it's still a switch or a potentiometer in the pedal that they are using.
I've wondered that myself since I got my RD-700GX. I guess a test with my multimeter and the pedal is in order

 

I wonder about half sustain. Is something cut from the sound? Maybe stereo becomes temporarily mono? Who knows. Or maybe what we think sounds like partial sustain is just a ton of reverb or some other effect.
On my RD, whatever it is, it seems pretty good. I've only tried with my foot, so I'm not sure if its truly continuous, or three discrete positions, but I can go between no sustain, full sustain, and partial sustain as I choose, and the notes ring out or don't like I suspect. Lifting off the pedal makes it sound like I've muted the strings, and I can "catch" the notes with it too.

"I'm so crazy, I don't know this is impossible! Hoo hoo!" - Daffy Duck

 

"The good news is that once you start piano you never have to worry about getting laid again. More time to practice!" - MOI

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Sue - I apologize - "polarity" is the usual term used by musicians and the companies that sell pedals. It just happens to be incorrect from an electronic techie standpoint, and I was attempting to explain WHY the particular pedal that you made a picture of the switch would not work.

 

I don't have the M-Audio, but a check of a couple of on-line vendors does show that it can quickly be changed for either "polarity," so one of them would likely work.

 

On to the next big keyboard pedal question - do you want one that looks like a piano pedal, or one that is the little square that is stepped on?

 

I just bought another used dual Kurzweil pedal, going to modify it also to a triple pedal (if I can find one more of the older Italian made single pedals. I like the weight, doesn't move around on me as much, and the pedals stay in the same relative position with each other. I STILL wonder why no one is making a triple-pedal that is imported into the US.

 

Howard Grand|Hamm SK1-73|Kurz PC2|PC2X|PC3|PC3X|PC361; QSC K10's

HP DAW|Epi Les Paul & LP 5-str bass|iPad mini2

"Now faith is the substance of things hoped for, the evidence of things not seen."

Jim

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Some keyboards will sense the "polarity" of the switch upon power up, and adjust accordingly.

 

My N364 has a global setting to allow me to choose normally open or closed. But my Sp-200 does not.

"In the beginning, Adam had the blues, 'cause he was lonesome.

So God helped him and created woman.

 

Now everybody's got the blues."

 

Willie Dixon

 

 

 

 

 

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Sue - I apologize - "polarity" is the usual term used by musicians and the companies that sell pedals. It just happens to be incorrect from an electronic techie standpoint, and I was attempting to explain WHY the particular pedal that you made a picture of the switch would not work.

 

No problem at all! I appreciate standing corrected and it's good to know I can't reverse the polarity. ;)

 

BTW, I don't know whether I have to bother unsoldering the wires to put them back the way they started out. It still works as a closed circuit switch but I've got the insulated wire connected to the ground. Is the whole thing likely to go up in smoke? Eh, I'll put them back anyway. Good practice with the soldering iron.

 

I don't have the M-Audio, but a check of a couple of on-line vendors does show that it can quickly be changed for either "polarity," so one of them would likely work.

 

Most online vendors and some users also claim that the SP-2 is capable of half-pedaling. Not true. Otherwise it looks like a fine pedal.

 

On to the next big keyboard pedal question - do you want one that looks like a piano pedal, or one that is the little square that is stepped on?
The pedal is for my daughter who has a PX-130. It shipped with the little square one and she'd like a piano-style pedal.

 

I just bought another used dual Kurzweil pedal, going to modify it also to a triple pedal (if I can find one more of the older Italian made single pedals. I like the weight, doesn't move around on me as much, and the pedals stay in the same relative position with each other. I STILL wonder why no one is making a triple-pedal that is imported into the US.

 

That's a good project! I use the triple pedal made for the Promega. It's worth the extra weight in the bag and feels natural. That sustain pedal does have a pot. I can connect it to another pedal jack and specify that it control volume. Not that I would. It's a pretty short throw and rough. :D It sounds like 6 or 7 values are sent.

 

Soooo.... a continuous sustain pedal that's a CV pedal. But what's it controlling when inserted in the damper jack? Not simply volume... notes have a different ring and a tail that's absent on release without the pedal.

"........! Try to make It..REAL! compared to what? ! ! ! " - BOPBEEPER
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Sue - I apologize - "polarity" is the usual term used by musicians and the companies that sell pedals. It just happens to be incorrect from an electronic techie standpoint,

 

He's quite right. The techie will call it a "mom(entary) on or mom(entary) off switch. Meaning you press it at it goes on (off) for a moment until you release it.

 

Sometimes this gets called a unlatching switch but that only tells you the momentary bit. The other sort that is useful to a musician is a latching switch which goes from om to off when you press it and back again when you press it again.

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Fatar makes the Pro Mega triple pedal. They make it in several different configurations

http://www.fatar.com/intere/dynamic_13.jpg

http://www.fatar.com/intere/dynamic_17.jpg

http://www.fatar.com/intere/dynamic_23.jpg

 

The linkage is tied to a POT, 10K if I remember right. The TipRingSleve works like an adjustable voltage divider. When connected correctly a variable voltage is read and in a simplified explanation the release is varied accordingly. It gets more complicated with the drake system, Pianotec Ivory etc...

http://www.fatar.com/intere/VFP3_13.jpg

they also make a square momentary in NO or NC and the same in a piano style

http://www.fatar.com/intere/PS_150_intera2.jpg

http://www.fatar.com/intere/VFP1_13intera.jpg

Triton Extreme 76, Kawai ES3, GEM-RPX, HX3/Drawbar control, MSI Z97

MPower/4790K, Lynx Aurora 8/MADI/AES16e, OP-X PRO, Ptec, Komplete.

Ashley MX-206. future MOTU M64 RME Digiface Dante for Mon./net

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Nice pics and nice concise explanation.

 

Looks like the same pedal unit on the top left, a single pot for the damper, with the exception that each pedal has it's own plug.

 

The "momentary NC piano style pedal" is the one I thought I could modify.

 

End of story. Thanks again for all the replies. I really appreciate the help.

"........! Try to make It..REAL! compared to what? ! ! ! " - BOPBEEPER
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Ah. One last thought. Any reason why I couldn't use the PCB from the Casio pedal she's wanting to replace?

 

You are becoming quite the geek, Sue. :thu:

 

I speak for all of us guys here when I say...

 

WE'RE SO PROUD. :love:

 

 

"Music expresses that which cannot be put into words and that which cannot remain silent." - Victor Hugo
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I thought that most modern keyboards had a sensor that polled the pedal state upon start-up and were thus adaptable to whichever way the pedal was wired.

For instance, I have a fleet of Yamaha electric pianos that I use with my piano class. If the student has his/her foot on the sustain when the piano is powered up, then the pedal works backwards. The power switch has to be cycled without a foot on the pedal for the sustain to work correctly.

My Alesis Quadrasynth had this feature back in '94 and I thought this was all well-settled! Did some manufacturer feel the need to futz with this?

Muzikteechur is Lonnie, in Kittery, Maine.

 

HS music teacher: Concert Band, Marching Band, Jazz Band, Chorus, Music Theory, AP Music Theory, History of Rock, Musical Theatre, Piano, Guitar, Drama.

 

 

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I'll trim the darn thing to fit. And I've got a hole puncher for hammer on snaps that looks like right size.

 

I'll let you know if I get lucky. ;)

 

And thanks, Tom. :D

"........! Try to make It..REAL! compared to what? ! ! ! " - BOPBEEPER
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Nice pics and nice concise explanation.

 

Looks like the same pedal unit on the top left, a single pot for the damper, with the exception that each pedal has it's own plug.

 

The "momentary NC piano style pedal" is the one I thought I could modify.

 

End of story. Thanks again for all the replies. I really appreciate the help.

Yea mine too, I think it's just a for display purposes image

Triton Extreme 76, Kawai ES3, GEM-RPX, HX3/Drawbar control, MSI Z97

MPower/4790K, Lynx Aurora 8/MADI/AES16e, OP-X PRO, Ptec, Komplete.

Ashley MX-206. future MOTU M64 RME Digiface Dante for Mon./net

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Sue, usually the PCB is the part that breaks. If that part works and you can make it go, good for you!

 

In any case, if you buy a pedal, just hoof it to your local Guitar Center (eep) and choose any pedal you like that has a "polarity" switch. Or the one Lerber posted above, which will be cheaper but take longer to get into your grubby mitts. Sorry, I mean your talented fingers.

 

Yes, "polarity" is techically incorrect. They should call it a "sense" switch, but if they did, nobody but electogeeks would know what they were talking about.

 

No need to put the wires you reversed back as they were. It's all good; there's no significant difference between the two contacts in this case.

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Well, thanks again for the recommendations, and to Jeff for noting I don't have to redo the original wiring.

 

So. I picked up a working Casio square pedal for nothing, took it apart (never to be put back together again.. those things spring apart like a jack-in-the-box...

 

No problem cutting the board down to size and drilling holes to set and screw it into the the other casing.

 

Connected the wires, had to GLUE the bubble contact in place because it didn't have the expected tiny rubber pegs, ..

 

put it together....

 

plugged it into a Privia..

 

Didn't work. Sustain at all times, both pedal up and pedal down.

 

The problem is the difference in design of the bubble contact - it's twice the height of the other.

 

At least that's the way I explain my failure.

 

Oh WELL.

 

:wave:

"........! Try to make It..REAL! compared to what? ! ! ! " - BOPBEEPER
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