9v problem?! Please help new builder!

[dangertheis]

Hey guys! This is my first post, and I am hoping that someone will be able to help me. I am building a pedal based on the Em drive and I am hitting a hard, crappy wall. I get a clean tone though my pedal when it is not powered (like I should) but when I plug the 9v in, whether it is a battery or the wall wart, the sound immediately cuts out. I have taken the dang thing apart a few times, bypassed the 3pdt, and have run out of ideas. Can anyone out there help me?
Thanks in andvance!
-DangerTheis

[GermanCdn]

First guess would be your ground and 9V are reversed.

[dangertheis]

Hey, thanks for the response. I have tried to reverse them to no avail. The longer 'stem' on the 9v jack is positive, right? Just for kicks I'm going to go try it again.

[alanp]

Photo might be an idea. Also, your power supply is tip ground, right?

[Clayford]

Sounds like the first place to start is your 9v connections. Center pin is Ground/Neg, with the sleeve being +9v/Positive. If you're using them backwards, you're putting +9v on every ground connection you have and that would explain your loss of sound with connection of battery or PS. Depending on the circuit - you might need to replace some parts due to this.

As has been already mentioned, clear sharp pics of the front and back of the board and your wiring will assist in troubleshooting.

[flanagan0718]

+1 on the Center positive. Make sure the 9v adapter is the right polarity as well. When i first started playing guitar I fried my dad's phase 100 hooking up the wrong wall wart (center negative).

[Clayford]

Ok - the +1ing of a positive tip and the mention of a pedal that uses AC power has me saying,
"Let's stop for a second and figure out something, What power scheme and jack are you using?"

9v DC? The standard knobikon style input power jack with a BOSS style 2.1mm with a negative center pin connection?
Looks like this?



All of the Em Drive circuits I know of should use this wiring method.
I really can't think of a reason you would wire it differently. If you're going to use a so called "positive ground" effect, the best practice would be a charge pump inside the enclosure and/or a battery unless you have a rather expensive isolated power supply, and even then building it with a charge pump ensures "standard" 9v (negative center pin) Boss style power supplies can power your pedal. These are so common even Dunlop switched over to them.


So check your power connection and if at all possible provide a link to your build documentation, and sharp clear pictures of your board (front and back) and your wiring.

Pardon my copy pasta - I'm at school not at home where I could grab pics.

remove incorrect wiring scheme

[mandrewbot3k]

http://www.madbeanpedals.com/tutorials/downloads/StandardWiring_MBP.pdf

Do you have  the battery snap hooked to the input ring like this? so that when you plug in the 9v, the battery doesnt get wasted.

[Clayford]

http://www.madbeanpedals.com/tutorials/downloads/StandardWiring_MBP.pdf

Do you have  the battery snap hooked to the input ring like this? so that when you plug in the 9v, the battery doesnt get wasted.

Almost - the power jack if wired correctly prevents the battery from being wasted when a 9v power supply is used. The wiring you pointed to prevents the battery from being drained input cable being inserted. Much better than what I had up there. Good catch!

[mandrewbot3k]

http://www.madbeanpedals.com/tutorials/downloads/StandardWiring_MBP.pdf

Do you have  the battery snap hooked to the input ring like this? so that when you plug in the 9v, the battery doesnt get wasted.

Almost - It prevents power period without an input cable being inserted. Much better than what I had up there.

I guess that was a little confusing. On my pedals when 9v is in and the input jack plugged in, they will not work, even with a battery installed. I need to unplug the 9v for the battery to kick on.

[Clayford]

I had it a touch wrong as well. The knobicon power jacks are switched. If wired correctly(Following Bean's wiring diagram) they will disconnect the 9v Battery when a power plug is inserted. If they don't - there's a problem. I've only wired up 3 of my pedals for a 9v battery - but they all function that way.