To get a third pedal on my PSR-SX900, I've been using a MIDI Solutions F1 Footswitch Controller. I programmed it to send a sustain on/off message to the keyboard when I press a sustain pedal.

A month ago, I was getting reverse polarity problems, so I swapped my Yamaha FC5 pedal and my MIDI cable.

I started getting more reverse polarity events (pedal off=sustain on), so I swapped pedals again.

Then I started getting very weird stuff occasionally. I would change a voice while the sustain pedal was on, and a portamento effect appeared on all of my voices. This happened twice.

During another performance, twice while hitting the footpedal, my registration would change to the first registration in that file folder. How could that happen? The gizmo is just sending a sustain message. Is it sending some complex Sysex command?

Since this footswitch controller is 10 years old, I decided to buy another one ($100), but in the meantime I swapped the one-month old MIDI cable with a new one.

In my last two performances, I've had no problem. So my question is, is it possible for a bad MIDI cable to cause all of these problems? Reverse polarity, portamento, registration change?

I wonder if it was the disconnecting of the cable that reset the unit? Was it controller powered thru midi?

Mid cables can be very fragile and go bad though they look new. Once I was working with the MIDI event processor plus. I wasted over two hours only to find out it the bad midi cable. I should have known it from having gone though a number of bad midi cables and purchasing a cable tester. The cable was almost new and it just didn't occur to me.

No. I swapped the MIDI out. The unit gets power from a USB MIDI interface plugged into the MIDI IN and the USB plugged into a phone charger.
I emailed tech support at MIDI Solutions.

I love MIDI Solutions products and have had mostly good experiences with them. I did have a footswitch controller get wonky on me. I replaced it with one from the latest generation that can accept power from a 9V adaptor. So far it's working reliably.

The manufacturers, especially Yamaha, no longer consistently provide power over 5-pin DIN MIDI. So reliable power and ground isn't a given. The "MultiVoltage" devices are MIDI Solutions' way of working around this. Not apologizing for what could be a defective product, but food for thought.

Yeah, starting with the S900, the power coming from the MIDI out of my Yamhaa was insufficient to power my MIDI Solutions unit.

I never heard back from MIDI Solutions, but I've done another two gigs with the new MIDI cable, and I'm not having any problems. So I bought an extra MIDI Solutions F1 that I don't need. If anyone wants to buy one of the two. I think I'll keep the new one and sell the old one but first test it for a few more weeks.

For those who have old fashioned MIDI cables in your setup, I did two more shows with a new MIDI Out cable, and I had no issues.

John Fast at MIDI Solutions confirmed via email that a bad cable could be responsible for the unwanted behavior. Instead of sustain on pedal down, I had sustain on pedal up, a portamento effect added to my voices, and the keyboard jumping to the wrong registration. He said that if the cable shorts out in the middle of a MIDI command, the keyboard might receive just a fragment of the command. Maybe even two fragments could get spliced together.

Yes, fragile midi cables....

Oy ve. So last show I had a MIDI reverse polarity event with the new cable, and then I had this situation where in the middle of my performance, I wound up at the first registration in the file folder and with the style associated with registration button #1 playing. I had registration freeze on. What the hell is going on? I'm thinking that this must be the keyboard. I wasn't even sure that I pressed the footpedal.
What MIDI or Sysex event could do this?
I had bought another MIDI Solutions device, but it's defective.

As I have two SX900 keyboards, I think I'm going to switch.