switch pops (i've tried everything!)

[nobodyknowswhereheis]

I have a 3pdt on/off switch that's popping on an overdrive that I built and I can't get rid of it! i've tried everything that you would usually do to eliminate it and it's still there. I built two of the pedals and one pops the other doesn't and I even tried replacing the switch. any ideas?

[foxfire]

well what exactly did you try? if you have a led, have you determined whether or not it is causing the pop? rylan

[R.G.]

Use your meter and check the output of your pedals for having a DC level over about 10mV. Anything bigger than that will cause big pops, and no amount of pulldown resistor bandaids will fix it. This is often - but not always - caused by an electrolytic capacitor at the input or output of a pedal being put in backwards.

[Mark Hammer]

As foxfire notes, with the advent of inexpensive and available 3PDT switches, many folks have been using them to implement a status LED.  Since LEDs draw current too, the sudden connection that powering up an LED provides can also create a source for audible pops, even though all the audio-related sources seem to have been dealt with.

Jack Orman has some advice about this over at his site, I believe, although there are probably multiple threads about that very topic here because it is a common concern.

[AceLuby]

What are the two pedals?  Which one pops and which one doesn't?  Schematic for each?  How are you wiring your switch?

Personally I wire my switch so that the board grounds when it is off and have a cap in my LED section between two resistors connected to ground.  The more info you can give on what you are doing the better.

[aron]

>Use your meter and check the output of your pedals for having a DC level over about 10mV. Anything bigger than that will cause big pops, and no amount of pulldown resistor bandaids will fix it. This is often - but not always - caused by an electrolytic capacitor at the input or output of a pedal being put in backwards.

This should be in the FAQ, so logical.

[nobodyknowswhereheis]

the led was the first thing I tried. but with it gone i was still popping. to answer your questions ace it's basically my own take on the tubescreamer with a gain boost and i changed around the tone stack a bit to better suit my rig. I built two, one for me and one for a friend. the one I made for myself works great but the other one pops. and I have the switch wired up according to general guitar gadgets true bypass 3pdt with led diagram. the input is grounded and so are the dc jack and battery jack. I've been over the circuit so many times everything is in it's right place and orientated correctly.
I'm trying to test the output level now but can't find a damn power supply or battery.

[R.G.]

I've been over the circuit so many times everything is in it's right place and orientated correctly.

We have a fair amount of experience with people trying to get effects to work around here.

That statement, or a variation of it, is what the vast majority of these people say - until the problem is found. It is even possible that it's true for you, unlike the others.

Going over and over your circuit often causes a kind of blindness to the faults. We're all human, eh?

[AceLuby]

Well, sorry to tell you this, but if one pops and the other doesn't, there is something different between the two.  My guess would be a backwards electrolyte cap.  Quintuple check the orientation of these.  Keep the LED wiring out of the pedal until the switch popping is figured out.

My suggestion would be to compare your two pedals and make sure everything is the same between the two first.

[any]

Just to throw my two cents in, some switches turn bad
if you heat them up for too long while soldering.
I had this happen on me once or twice and unfortunately
the switch itself was popping.
It usually doesn''t happen as much on the blue 3PDT switches
as it does on the alpha 2PDT but it does happen sometimes.
I always solder my switches as fast as possible and preferably
with a "heatsink" of some kind like a pair of tweezers attached to the lug.

[nobodyknowswhereheis]

appearently this pedal pops on some rigs but not others.. does that make sense?

[gez]

Have you measured for voltage, as was suggested earlier?

Forgive me if I'm wrong, but you haven't given any feedback on this...in which case it's a little pointless asking more questions (IMO).

[aron]

>appearently this pedal pops on some rigs but not others.. does that make sense?

Well, I have seen some tube amps that have small voltages on the grid of the input tube which cause pops in pedals.

[nobodyknowswhereheis]

yes, I have measured the voltage as suggested earlier. I got a rating of .001 volts.

[nobodyknowswhereheis]

also I've put in a new switch with still no change.

[foxfire]

have you tried both pedals on the same rigs? just to see if the one is really pop free. rylan

[gez]

yes, I have measured the voltage as suggested earlier. I got a rating of .001 volts.

Did you measure both input and output?  Also, did you take measurements with both positions of the switch?

[nobodyknowswhereheis]

no. I'll give that a try!

[Boner]

Apologies for bumping an old and dead thread, but I wanted to chime in for a second.

I didn't even think about measuring output DC before stumbling on this thread. I went ahead and measured and found I had 300mV DC at my output... this is with an electrolytic cap filtering DC at the final output..... switched to a non electrolytic and the DC offset went completely away.

This might be a stupid question, but is there a solution to leaky electrolytic caps other than "don't use electrolytic, use a smaller value"?


Glad I checked, havent gotten to the part in this circuit where I actually wire up a stomp switch

[R.G.]

Solution to leaky electros? Use new, good electros. A 1M will happily pull down an undamaged electro.