Expression pedal is only on/off #UnO2

I Am Blake Carpenter

Hiya, my volume pedal works fine but my Exp pedal is only doing 0 (down) and 127 (up). Do I just need to do a 1/3 calibration or is there something else?


Have you calibrated yet?  Should be the first thing whenever something is wrong with the pedals.  Is it both or just one?

If that doesn't work... The pedals are Optical, with a plastic piece between the LED and the sensor that changes the amount of light as the pedal moves.  That plastic piece can become loose, or dust can get in there and block the LED light. If your FCB1010 is new, it might be worth it to return under the warranty.  That might not be possible if you have to open it, so don't open it if you're not comfortable with fixing that kind of thing.

I Am Blake Carpenter

Already calibrated and had to open it to swap to the uno chip. It is new but purchased open box from secondary seller so warranty is probably not an option. I do have the 1.0.4 chip so I wonder if it is the issue with that chip. 


v1.0.4 has been out for quite a while (like, years) and this is the first report I've seen of this problem.

Jack Fenton

If I remember, I had to do some sort of  memory initialization (in addition to exp pedal calibration), when I put my UNO firmware in.

There should be no reason 1.0.4 should not work unless you have a bad FCB1010.

David Grosz

Have you done the calibration for each pedal?

Also look at the gradient strip to make sure it is clean and check that the LED is
in the correct position.

Ir's doubtful this is a firmware issue but anytime I have had an issue it was from not getting the calibration done correctly.  you might also check to make sure that
none of the pins got bent or in the socket correctly

On Friday, February 11, 2022, 12:53:48 PM PST, I Am Blake Carpenter <blake@...> wrote:

Hiya, my volume pedal works fine but my Exp pedal is only doing 0 (down) and 127 (up). Do I just need to do a 1/3 calibration or is there something else?


As long as you did the required factory reset after installing the new firmware, the chip should not be the problem - especially if all the other functions work.  Take the bottom off again and look at the plastic 'gradient' strips connected to the malfunctioning pedal - it's pretty easy to see.  Make sure there's no dust or debris in there, and that the strips stay between the two parts of the sensor - the LED and the phototransistor - throughout the range of the pedal.  If not, try to rotate the plastic strip back to where it belongs:  Do Not Force It.  If it moved on it's own, it'll move without much force now.  Also check for any dust or debris in this area - even a hair can make it go funky.  This is actually fairly... well, I won't say 'common', but if something is physically wrong with one of the pedals, it's either got dust in it or the strip moved 90% of the time.

This article has a picture of the plastic strip with the gradient printed on it.  Unfortunately, they removed the hardware around it, but the strip should be sticking straight out like that one is.  If everything looks good with the gradient strip, you can look at the LED.  Sometimes it's bent too far over, like in that article.  If so, you can try bending it back carefully.  If it's not bent, or bending doesn't fix it, don't panic - there's one more thing to try.

If you aren't comfortable modding your FCB1010 like this, don't.

Sometimes the manufacturer gets a defective LED that's actually too bright.  Get a small piece of a colored plastic bag - the thin ones you can see light through, not the super-thick reusable ones some stores are using.  Wrap a single layer of plastic around the LED - and tape it in place.  Actually, you may want to test it before using anything like tape in there.

<< Disclaimer: I cannot and do not recommend testing it with the cover off, since that exposes Mains voltage connections. >>

Safely turn the unit on, factory reset (just in case), then calibrate the pedals.  If this helps (you see more than 0 and 127) but doesn't quite fix it, try adding another layer of plastic at a time until it calibrates well.