HD500X Train Wreck at Sunny Gig

So, I had my first train-wreck on stage with the HD500X. This was at the Twin Creeks Spring Carnival, so not exactly a high-pressure situation with a huge crowd, but still…

The first song in the set was Lonely Boy, in which I use a HD500X patch with the expression pedal as a pitch dive (heel original pitch, toe dive-bomb).

The pedal got itself into a state where heel was not the original pitch, so I was stuck in a different pitch playing off-key from the rest of the band.  I had to bail out of that patch (and all other use of expression pedal for wah/etc) until the break.

Between sets, I frantically Googled on my phone how to calibrate the expression pedal. I went through the process(power cycle holding down the right arrow, choose Pedal Cal, etc) several times but the heel/toe values I was seeing were whack. I managed to get it close to correct (but still not the expected 0 and 255), and I got through the gig with it still acting strange.

After getting it home and trying it again a few days later, it all seems fine.

The gig was on a beautiful sunny hot day on an outdoor stage.  Maybe the unit was over heating??

Line 6 tech support advised the usual tips- flash the firmware, recalibrate the pedal, hit it with compressed air in case there’s some debris blocking the sensor.  However they also said:

The expression pedal’s sensor is optical, and uses an LED’s brightness to control the values. If the angle of sunlight happened to reflect into the sensor at just the right angle, I can see how this might cause some weird behavior. It’s very rare, and the sun has to be really bright and reflect just so, and I haven’t heard of it happening before, but I can imagine that under the right circumstances…

Hm, so I guess it’s just something to keep an eye on at our next outdoor gig. My confidence in my rig is a bit shaken!

Update August 2, 2015: I can now confirm that this is definitely related to sunlight getting into the optical sensor! This issue happened again at last night’s gig with the Drop Daddies!

We sound checked around 6pm, and the setting sun was hitting me full in the face. The pitch/wah on the HD500x was off-kilter again, just as I reported previously. I reached down to shade the wah treadle with my hand and I could hear it change to the correct pitch as my hand cast a shadow over the pedal.

So, it was the sun shining into the optical sensor after all! The gig was after sunset, so no problem this time, but I’ll need to figure out a workaround for this, as we play a number of outdoor gigs each year!

Update January 31, 2016: Looks like this issue is resolved in the new Helix!