Connection Help for non-Yamaha Volume Pedal

[acparker]

Hello everyone.

I have the opportunity to repurpose an old, defunct Church Organ to work with my Genos.  The keyboards and Pedal Board are simple enough -- I did a smaller Pedal board adaptation earlier.  They will be a much bigger and tedious job wiring, though.  But I am wondering if I can modify the Volume pedal to work directly with the Genos, or if I have to wire it through the Arduino board.

Can anyone tell me if the Genos Volume Pedal works as analogue (voltage level) or is it digital?  Could someone provide the schematic for the plug?

Thanks!

Adam Parker

[BogdanH]

hi Adam,

Original pedal Yamaha FC7  is analog device. If I remember correctly, there's 50kOhm potentiometer inside.

Bogdan

[overover]

Hi Adam,

The Yamaha FC7 pedal contains a 50 kΩ (linear) potentiometer. For the exact wiring, please see the attached picture. It comes from the FC7 Owner's Manual and I've added some important information.

By the way, the exact value of the potentiometer is not that important since it only works as a voltage divider. It should also work with 100 kΩ or even with 10 kΩ. However, I recommend a 50 kΩ pot.


Hope this helps!

Best regards,
Chris

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[acparker]

Thank you both for your replies.  That was exactly the sort of information I needed.  Now, to see what the ol' organ uses in its foot pedal ...  That'll likely be tomorrow.

Thanks again!

Adam

[overover]

You're welcome Adam!

P.S.
Please note that foot pedals should always be connected before switching on the keyboard, as the polarity of the pedals is automatically detected during the boot process. For example, if you connect an expression pedal like the FC7 while the keyboard is already running, the pedal may work "in reverse" (fully depressed = minimum value). In this case you press "Direct Access" and move the pedal up or down a little to open the Assignable display. There you can switch the polarity for the pedal in question (touch the Menu icon).


Best regards,
Chris

[acparker]

Hey overover, thanks for the reminder.

Out of curiosity,  how does the keyboard automatically detect the polarity? 

Adam

[BogdanH]

Speaking for PSR-SX keyboard...
In manual it's said "Do not connect or disconnect the pedal when the power is on.". It doesn't say why's that, but it's not because keyboard would check pedal polarity at power on and/or influence pedal functionality (because it doesn't). Reason for that precaution measure is: pedal socket has 5V on tip of the jack. And so, when we deal with voltages, we should always make connections first and then turn the device on -simple as that.

On PSR-SX keyboard we can't switch pedal polarity -it's assumed that pedal will have correct connections. And because of that, it can happen that some non-original sustain pedal will work in opposite way. Advice: if buying 3rd party pedal, make sure it has polarity switch.

PSR-SX doesn't differentiate between sustain (switch) pedal and expression (volume) pedal. The only thing that keyboard memorizes is pedal functionality, which is determined by the user. For example, if we set sustain functionality, then pedal will work as sustain -regardless if we use switch or expression pedal. Or opposite, we can use switch pedal and set it's functionality to volume (obviously volume can only be on/off in this case).

In short: for expression pedal to work as expected, the potentiometer must be wired properly (as shown on image that Chris posted above). For example, if we wish volume to increase as we push pedal forward, but pedal does exactly opposite, then we need to switch both wires on each end of potentiometer.

Bogdan

[overover]

Hey overover, thanks for the reminder.

Out of curiosity,  how does the keyboard automatically detect the polarity? 

Adam

Hi Adam,

It's not quite as Bogdan describes it: Yamaha keyboards definitely check the polarity of the connected pedals during the boot process. A Yamaha foot switch (momentary switch like FC5 and FC4) has the polarity "contact normally closed", but foot switches from other manufacturers also work, most of which have the polarity "contact normally open".

Basically, it is important to ensure that the connected foot pedals are not pressed during the boot process. Otherwise, as mentioned many times, they may work in reverse. As mentioned, this could also happen if a pedal is plugged in after the keyboard is already switched on. (In many cases it will still work normally, but this COULD result in the described error. )

Incidentally, I am not aware of any case where the internal electronics were destroyed by connecting pedals during operation. The pedal inputs are protected against short-circuiting of the control voltage (+5V) by appropriate protective resistors, so that nothing can normally be destroyed.

The pedal detection probably takes place after the "Boot second stage start", i.e. if the status of the internal keyboard and all internal switches are taken in. This takes place directly before the Linux kernel starts.

The current status (and thus the necessary polarity setting) of a momentary switch (e.g. on/off sustain pedal) is easy to determine (contact either closed or open). Unfortunately, I don't know how exactly the keyboards detect the status/polarity of a connected Expression pedal (e.g. FC7). In any case, there is a test routine in the internal Test program that can be used to determine whether a connected FC7 pedal supplies the correct values ​​for "Pedal Down" (maximum position) and "Pedal Up" (minimum position).


Best regards,
Chris

[overover]

...
On PSR-SX keyboard we can't switch pedal polarity ...

Hi Bogdan,

We CAN set/switch the Polarity of connected foot pedals. On PSR-SX and Genos, as mentioned above, you have to touch the "Menu" icon in the Assignable display. Also see the attached screenshot (taken from Genos).

Quote from SX900 Reference Manual, page 111:

If necessary, set the polarity of the pedal by touching [Menu].
Depending on the pedal you've connected to the instrument, it may work in the
opposite way (i.e., pressing it has no effect, but releasing it does). If such a case
occurs, use this setting to reverse the polarity.


P.S.
If the two outer contacts (of the resistance track) of an expression pedal's potentiometer are reversed (i.e. SLEEVE and TIP contacts of the TRS plug), this can be corrected by switching the polarity Foot Pedal / Assignable display. But the so-called "wiper" contact, i.e. the middle contact of the potentiometer, must always be connected to the RING contact of the TRS plug for use with Yamaha keyboards. (On e.g. Roland expression pedals, the wiper contact is connected to the TIP contact of the TRS plug, which is why these pedals only work on Yamaha keyboards after appropriate modification.)


Best regards,
Chris

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[BogdanH]

I stand corrected Chris (a.k.a. Yamahapedia)... I better keep my mouth shut 

Greetings,
Bogdan

[overover]

I stand corrected Chris (a.k.a. Yamahapedia)... I better keep my mouth shut 

Greetings,
Bogdan

No problem Bogdan, you are doing a great support work here in the forum! Everyone can make mistakes. (Even I've been wrong many times... )

I just don't want details that are obviously (or presumably) incorrect to remain uncommented and I'll try to answer as precisely as possible so that other users aren't confused. And I am very grateful when other users correct me if I've written something wrong.


Best regards,
Chris