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Need Expression Pedal Help

SirPsycho
 

Ok, not sure if I have a mechanical issue or setup issue.

I have an FCB1010 with an UnO 1.0.4 chip. Everything's working great except expression pedal B (the furthest one from the switches).

I'm only getting midi CC from the top half of the sweep. Using Midi Monitor, the control values don't really change from heel down to toe down until the half (really 30%) of the movement. I've tried calibrating, and I'm getting the exact same results every time. When looking at the readout while calibrating, Expression pedal A show hex values from 06 to F1. For Expression pedal B, I see 06 to A1 or A2 at best. And the readout stays at 06, 07, 08 for a majority (70%) of the travel.

Is this a mechanical/electrical issue or am I doing something wrong?

Mcleish, Mike
 

Have you looked inside?

The pedal components are rather flimsy. It may be a mechanical problem, like something is bent or broken.

Remove the bottom panel and compare pedal B with A while moving each. Send some pictures.

Mike McLeish
812.249.8701

chrisw_63
 

The expression pedals work by moving a clear strip that gradually gets darker through a light sensor with an LED on the other side.  Here's an image of it.

There is a known issue where the transparent graduated strip isn't held firmly, and can move away from the IR detector.  When the pedal goes toe-down, the closer part of the strip moves back into the detector.  That sounds exactly like what's happening with yours.  If you're comfortable trying the repair yourself, I've heard it's not hard to do.  Otherwise, if it's still under warranty, you might want to send it in, or ask someone local to help you fix it.  There are mods and fixes for it on the web.  I haven't seen them all so I won't endorse or recommend any, but they should collectively give you an idea of how to get it working again.

SirPsycho
 

Mike & Chris, 

Thanks for the info and pics. I got it figured out. If you look at the PCB assembly for the expression pedals, the LEDs shining on the sensors are NOT at right angles. They're slightly offset. My Expression pedal B was right at 90 degrees. I bent it slightly and recalibrated, now I have full range of motion 100% thru the sweep. 

I guess too much light was shining on the sensor to properly register the movement.

sp

chrisw_63
 

That's actually another known glitch.  The most common fix is a layer or two of thin plastic from a shopping bag.  Next time someone has those symptoms, we'll know to tell them to try your easy fix first.  Thanks!