Big Muff Pi Issues

[miracle]

Hello Everyone.

I'm having issues with an NYC Big Muff Pi (resembling this one here) which I was hoping to get some guidance about here.

In the off position the clean sound comes through cleanly. When the unit is switched on the LED comes on but the majority of times the guitar can barely be heard through the amp and is not distorted. Now and then when the unit is switched on it will function normally.

All connections including GND seem good. I am assuming the problem is with the switch but the switch is not one I have come across before.

Could anyone advise as to a suitable replacement part or recommend something that I might be missing?

Thanks.

[52 Bill]

...Now and then when the unit is switched on it will function normally.

Try cleaning the switch with some Deoxit.

[Mark Hammer]

All stompswitches have little "rocker" contacts inside that pivot on their middle. During assembly, a small dab of grease is applied to that pivot point to both hold the rocker contact in place so that it doesn't fall out, and damp vibrations to avoid switch bouncing. When too much heat is applied during assembly or repair, the heat can cause the grease to flow and unintentionally coat the contacts, leading to either intermittent contact or complete switch failure. It's a bit like the way dust buildup inside older style "ball" mouses would render them unusable.

Happily, you CAN disassemble and reassemble the switch in many cases. Pry the tabs up gently, and the switch will separate into top and bottom halves. Once the switch is apart use tweezers to pull the rocker contacts out, clean 'em up good with a Q-tip or even a kleenex, and place them back in. I've rehabilitated several switches this way.

[miracle]

Thanks for the advice. I dismantled the switch and the contacts were indeed covered with grease. I cleaned this off and reassembled the switch however the unit will not work at all now. I'm unsure if I have assembled the switch correctly.

I also seem to have acquired two small pieces of silver sheet metal, about 1cm long by 0.5cm wide with two semi circlular notches in the middle which fell out the unit at some point - looks a bit like this


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I didn't see where they came from, are they part of the switch assembly?

[rockinrendell]

do you have any pix of the switch? together or apart. someone somewhere should have a replacement. trick is finding it. not impossible, just difficult maybe.

[oc disorder]

"I didn't see where they came from, are they part of the switch assembly? "

Yep they have to lay across the contacts.

It can be very fiddly ..maybe time to get a replacement foot switch.
one example
http://www.mojomusicalsupply.com/ite...797&id=4114111 - 16k -

[Mark Hammer]

Thanks for the advice. I dismantled the switch and the contacts were indeed covered with grease. I cleaned this off and reassembled the switch however the unit will not work at all now. I'm unsure if I have assembled the switch correctly.

I also seem to have acquired two small pieces of silver sheet metal, about 1cm long by 0.5cm wide with two semi circlular notches in the middle which fell out the unit at some point - looks a bit like this


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I didn't see where they came from, are they part of the switch assembly?

These are, in fact, the very rocker contacts I wanted you to clean. They should be seated back in their respective slots in the switch (and now you know why they use the grease to hold them in place!). The teeny indent in the middle is what should be in contact with the pivot point formed by the inside portion of the middle solder lug. Like I say, it's a tiny see-saw.

I can only hope that prying the tabs up to disassemble/reassemble the switch a 3rd time (once the manufacturer, twice for you) doesn't damage it.