B2 Expression Pedal Noise

[theseacowexists]

This just started recently. What might cause a crackling/static noise when the expression pedal passes a certain point in its travel? Something in the doghouse? Passing that point also seems to trigger the Trek II percussion unit if it is engaged and a note is being played on the upper manual B preset.

[theseacowexists]

I should also add that sometimes switching the Leslie from slow to fast, it will trigger the percussion if I am playing the upper B preset. It's a 145 btw

[muckelroy]

I can't make heads or tails as to why changing Leslie speeds would trigger percussion.

It would be worthwhile to blow out the swell capacitor with compressed air and scrub with alcohol / pipe cleaners to clear out dendrites or other debris. If there are dendrites inside the manual bins, all sorts of weird percussion issues may occur. I'd suggest zapping the percussion bus bars but in this scenario it might be a bad idea since you're using a Trek II percussion, so would not want to damage it.

[David Anderson]

On some rare occasions, the green wire inside the expression housing that loops around the pivot can cause noise if its insulation rubs against the pivot. The solution is to dress the wire in a loop that does not rub on the pivot. You should also check the pedal travel vs. the swell capacitor range, but if the swell capacitor goes too far, it usually simply grounds out the signal.

I have absolutely no idea what could link the expression pedal to the percussion unless the pedal linkage is tangled up in the wiring somehow.

[theseacowexists]

It wouldn't surprise me if that green wire was rubbing against something or some crud was jostled around when the organ was moved a couple months ago. It definitely didn't do this before the move. I remember over the summer I was having issues with the pedal being microphonic, and dressing that green wire seemed to help, but it may have repositioned itself in the move.

The Trek II unit on this organ is one I've never seen before. It mounts to the front rail, has three different settings (legato, touch and reiterate) and four percussion harmonics (8, 4, 2 2/13, and 1). I love how it's got all these additional functions! But I can't seem to find any info about it online. Looks pretty old too.

[Drawbar Dave]

Could you post a picture of the percussion unit just to satisfy my curiosity? I thought I'd seen all of the aftermarket units available!

[David Anderson]

If you're confused about a Trek II product, call Trek II. They are still in business and know everything about everything they've ever made.

[theseacowexists]

Sorry for the delay - here's pictures of the Trek II unit!

[Hamman]

Wow! That has to be one of the first percussion units they made! Maybe call them......they may want to make a trade for a newer unit just to have that old one back for their archives;-)

[muckelroy]

Might be off topic but is this a chop? Couldn't help but noticed the butchered pedal wiring harness. If so, how is the expression pedal wired up here?

[enor]

Ooo I LOVE that TREK box - wish they'd kept on making them that way. Switches, glorious switches, instead of the silly sliders on the current model!

[theseacowexists]

Enor - my thoughts exactly! Why don't they still make this unit?!

Muckleroy - yes it is a chop! A previous owner cut the legs just below the case and built a platform on top of where the legs were cut. The case just sits on this platform. The original expression pedal is intact. In order to move the organ in two pieces, the pedal rod needs to be unscrewed and removed. I can't imagine having to do that every time it goes out to a gig, which is why it's my studio organ.