Exp pedal calibration issue

J

Jberg

Member
I seem to be having issues calibrating my exp pedal.
  • Ernie Ball VPJR (with linear 10k pot mod)
  • TRS cable into Pedal 1 of FM3

I follow the manual:
Setup > I/O > Pedal > Pedal 1 Setup: 1 EXP Pedal

When I Calibrate Pedal 1 and move the pedal through the range of motion I see the indicator move on the calibration page (albeit it only moves about 30% of the whole length). Hit Enter.

But, when I insert a Vol/Pan block, and assign Volume parameter to Pedal 1(EXP/SW Tip), the indicator only moves through the top 30% of the line on the graph. And the volume never goes off, only goes down to about 50%. Am I doing something wrong? I never had this issue with my AX-8.

As an aside, the top 60% of pedal travel does nothing (i.e. it hits 100% vol in first 30% of pedal travel), on my AX-8 I adjusted the slope to compensate.
 
Update, I reset to factory settings hoping that would fix the issue. No luck. Not sure what to do next. Would a fresh install of 5.03 work? or is there any chance this is a bug with 5.03 that nobody has noticed because they haven't had to calibrate their pedals since May?
 
If the calibration is only moving 30% then it's not going to work.

Bad cable, bad connection, problem with the soldering on the pot or jack.

Did you try another pedal jack?
 
Thanks @unix-guy . I've tested and tried multiple TRS cables, also tested configuring it into Pedal 2, as well as one of the Pedal inputs on the FC-6, it still acts the same. I've taken apart my exp pedal, checked all the connections, even replaced the TRS jack because I thought there was an internal issue there, still no change. I guess at this point the only variable left is the pot itself, but as I said before, it all worked fine on my AX-8.
 
Check it with a multi-meter. Center wiper lug to either side lug on the pot should give you smooth linear change in resistance between roughly 0 and 10k ohms as you very slowly sweep the pedal. You can also measure between the tip and rig or between the tip and sleeve of the TRS jack or cable as well.
 
Thanks @mr_fender , exactly the information I was going to look up next! This is what I'm getting:

Tip to Ring:
8k ohms to 0 (heel to toe)

Tip to Sleeve:
no change, stuck at 9.5k Ohms

Ring to Sleeve:
1.5k Ohms to 9.5k Ohms (heel to toe)

Can you confirm what you said in your reply? You said "or tip to sleeve" but you also said center lug to either of the side lugs. I have center lug connected to Ring (per this thread https://forum.fractalaudio.com/threads/ultimate-ernie-ball-expression-pedal-mod.79648/)
 
Looks like your pot is wired wrong. The center lug goes to the Tip connector of the TRS jack. If the pot is facing away from you with the lugs pointed up, the left lug goes to the Sleeve connector, the center lug goes to the Tip connector, and the right lug goes to the Ring connector.
 
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if the pot is reporting its maximum at 30% of travel, calibration won't help because the Axe isn't getting more data beyond that. sounds like the pot is not wired correctly.
 
Thanks @mr_fender (and everyone else that responded). I did in fact have the pot wired incorrectly! It's now working and calibrating correctly.

So weird that I didn't have this issue with my AX-8, and that nobody has noticed the error in that thread from 2014. I'll go post a correction to it now. Thanks again!
 
You said you had to compensate the curve in your AX8. That's why. A 10k linear pot should require no compensation at all.
 
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Jberg said:
Thanks @mr_fender (and everyone else that responded). I did in fact have the pot wired incorrectly! It's now working and calibrating correctly.

So weird that I didn't have this issue with my AX-8, and that nobody has noticed the error in that thread from 2014. I'll go post a correction to it now. Thanks again!
Click to expand...
Hey - EXACT same calibration issue. I can have someone check my pot but curious if your tech told you how it was wired? Any specific advice or should a tech easily be able to see the problem? Thnx
 
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