Piano World Home Page Forums Our Most Popular Forums Digital Pianos - Electronic Pianos - Synths & Keyboards Yamaha's LP1 triple pedal - looking for internal wiring

witor -- I don't think the P-515 has a pedal calibration function feature.

But I managed to do the voltage measurements, and was able to find out that Pin 1 (connected to all the 'c' pins) gets +3.2 volt DC on it. Pin 5 will be the 0V reference. So pin 1 is the higher voltage pin, 3.2 volt higher than pin 5.

For the right-hand pedal (ie. sustain/damper pedal), the node 'b' voltage (ie. pin 2 for the right-pedal) for no pedal depressed is 0.85 volt. So that's around 27% of the full DC voltage.

And with the right-hand pedal fully depressed, I measure 1.8V for node 'b' voltage (ie. pin 2 is 1.8 volt higher than pin 5 when the right-hand pedal is depressed). That's around 56% of the full DC voltage. Although - in order to make the pedal 'depressed' - I have to insert plastic tabs after trying to hold down the pedal with one hand ...... so slotting a bunch of plastic tabs into the gap to keep the pedal down. It's possible that the pedal could have gone down a bit more --- could even reach 2 volt. But this gives is a good idea about what the voltage levels are for no-pedal and full-pdeal (or near-full pedal). And also the applied DC voltage and polarity.

FWIW, 3.2V makes sense, 3.30V is a common voltage for logic circuits and they took that to supply the pedal pots.
About the pedal going only down to 1.8V when fully depressed, it makes sense to, the mechanism probably turns the pot just halfway its entire range.

Nice post EVC. Thanks for adding that information as well! Definitely appreciated.

Yes 3.3V is a common voltage in this type of applications. Are voltages on the sliders of middle pedal and left pedal the same as for the right pedal? Do they also go from 0.85 to 1.8

I asked about calibration because in practice it is difficult to build a set of pedals like this and get very precise and consistent voltage range for all pedals. That's why I was expecting some sort of calibration mechanism that would tell the keyboard which voltage corresponds to pedal being released and which to pedal being depressed.

witor ..... I found this link .... where the P-515 doesn't have a cal feature, but instead has a way to alter the pedal's active zone ....... LINK

I checked the right-pedal during this afternoon. I will check the middle and left pedal as well. I just didn't get around to it ..... as this was done during lunch time. I live close to where I work. Stay tuned for the results on those other two pedals!

Amendment to be made with the information above. The measurements for the above was actually for the left-hand pedal. All other references to left, middle and right pedal for all other information are correct.

These are voltage measurements with the probes placed across the wiper point for each pedal's associated potentiometer and pin 5.


Also, the resistance of 1-2 was re-measured - and triple-checked, and turned out to be 3.4 kilo-ohm, so just including the updated resistance measurements in kilo-ohm units.



Also showing some extras - such as needing to jam enough plastic strips into a gap, in order to keep the pedal 'down'. That was a bit fiddly with not much to grip onto ----- while also avoiding touching the grease on the plate at the back. This plastic strip jamming needed to be done for each of the three pedals.



And - a look at the potentiometer, which appears to have no writing or details on them. They're 9 kilo-ohm pots though ----- at least we know that.

Once again big thank you for all your measurements. I have not yet decided if I will go ahead and build my own set or just buy one and mount it to something, but it is amazing that you have put all this effort just because some guy on the internet asked you to do so. I find this forum to be one of the best and it is because of people like you SouthPark.

You're most welcome witor. You helped me too - as we had the same interest with finding out what's in one of these. And I also thought that the existing details on the internet were a bit unclear ----- as in there was even uncertainty about whether the pin numbers on those existing diagrams were accurate or not. That is, they have some pin outs, but no clarity about whether they were looking at the holes of the female socket or looking directly from the front at the actual metal pins of the male connector. Whichever option you go for - it will be great. At least we know the voltage levels that the instrument needs for the pedal functions, and also found out that the left and middle pedals aren't just switches. I didn't expect that! And thanks for such excellent and most courteous posts from you witor. All the best!

Just to add one more thing if anyone ever wants to replace faulty LP1 potentiometer. The LP1 potentiometers look very similar to xbox 360 controller trigger potentiometers.

Nice one witor! I just did a search just a moment ago. It really does look like them. Excellent find. Thanks for mentioning that.

Thank you for all the help I have received in this thread. This is what I ended up with. Pedals work fine. Brace at the back is to push pedals against the wall and prevent them from sliding on the captet. It does the job! Sorry I don't know how to insert the picture here. You can see it in the link below.

https://forum.pianoworld.com/ubbthreads.php/galleries/3364153/diy-lp1-pedal-unit.html

That looks excellent witor! Nice work! And clever usage of bracing. Thanks for posting here again as well.

Also ... thanks to your info about xbox 360 pots, I'm currently modding a FC3A pedal ..... aiming to put in a xbox pot.

LINK

Nice work.

Good day all. I bought our kids a used DGX-670 which works great. We previously had (and still do) a DGX-650 with the stand and pedal unit. I'm frustrated to find out the 670 doesn't work exactly with the stand (though it does with a little encouragement) and the pedal unit doesn't work at all. Apparently they changed the wiring configuration when going to the 670. Frustrating that Yamaha chose this design just to make a few extra buck from buyers, but I digress.

I've read the 3rd party 3-pedal units don't work great. My question is, has anyone come up with a plug/wiring adapter for the 6pin DIN plug that would allow the 670 to talk with the 650's pedal unit? Final option is to simply buy a new LP1 and attach it to our stand but that defeats the purpose. Any thoughts on this?

Witor - Nice design!

Thank you and (almost) Happy New Year.