I have a couple of builds (Abyss & Cobalt Drive) that pop when turned on. I thought it may be the crappy 3PDT switches I used but swapped them out for Alpha 3PDT ones and still get the pop.
I just plugged my Abyss in and played with it,
It's completely Silent, No Pop at all.
Have you switched the Pedal on & played for 30 seconds then switch it Off, Is the Pop still Present. If not, Your Electrolytic caps may have excessive Leakage.
Have you tried just turning the Footswitch On & Off half a dozen times leaving 5 seconds between switching.
If it disappears, You have leaky Input or Output Caps. Read link :
I haven't tried this myself, but this article may be very helpful for some Whether there is a pop when you bypass or un-bypass a box depends on whether the internal circuits have been carefully designed to prevent it, or if there is a flaw in the circuit that makes a formerly-quiet box now pop at...
www.harmonycentral.com
Another reason for excessive Pop can be a bad solder joint or Dry Joint.
While Pedal is switch on, Tap the pedal on the Carpet Firm but Lightly and see if the Pop is present.
If so, You need to find the faulty joint
