9v battery works but dc power doesn't

[macjohn]

This is my first complete pedal build: http://www.3pdt.com/products/bender-mk-ii-fuzz-pcb
all stock parts (except the dc jack which I'll explain below).  I intended to NOT use the 9v battery clip but added it on for troubleshooting.  I found that the pedal works fine with a 9v battery, but I can't even get the LED to light with the power supply.  This is a positive ground tonebender MKII fuzz.

I ordered some additional DC jacks and have swapped out the original to ensure that wasn't the problem.  I read the troubleshooting guide and have the following data with my multimeter for the 3 transistors:

Q1 E=8.95   B=3.94   C=3.76
Q2 E=8.95   B=4.84   C=4.76
Q3 E=8.47   B=4.76   C=4.66

I'd continue posting data but I confess I don't know what an IC is.  I assume it has to do with capacitors?  I measured the board in and out and they were at 8.95 and most of the other things I touched were in the 4 range.

So, if this works fine with a 9v battery, it seems like there should be something easy that I've missed.  Any help appreciated.  I can document more values if you think that'll help.

[davent]

Being a positive ground pedal and at this stage of the game i'm going to recommend going with a battery, i would think that that circuit has a very low current draw and the battery will last a very long time as long as you remember to unplug the guitar from the pedal when done using it. And no IC's to worrry about in there.

If you were to daisy chain this pedal with other pedals which are negative ground and usually the case things could go catastophic.

You need a power supply dedicated to your positive ground pedals or if not this pedal needs a charge pump (IC) and components  to create a third and negative power rail to power the positive ground circuit and play nice with the negative ground pedals in the daisy chain. All very confusing.
dave

[macjohn]

Thanks for the tips.  I don't use any daisy chaining.  I'm using a Voodoo Lab Pedal Power 2 + and have a positive center pin adapter that I use successfully with my Fulltone 69 which I think has the same power demands as this pedal.  I've also tried the stand alone fulltone 69 adapter with no luck.

Odd thing was, when I first wired this, I screwed up a couple wires (can't remember what I did) but the pedal didn't work but the light lit up with power.  I quickly realized the mistake and wired it correctly, since then it's only worked under battery.

I'm really wanting to put this on a board which would make unplugging a challenge.  Can I get a 9v adapter to plug into the battery clip and be powered like a normal pedal?

[shrubbery]

If it works with battery and is not daisy chained then only thing I can think of is swapped DC connection.  Positive ground is a relative thing, you can just swap the inputs to get negative ground if you don't daisy chain.

If battery works this means you put +9V (red) to ground in the circuit (-9V on DC input).  With DC plug there's another thing: center negative or positive (you shouldn't use center negative with metallic socket and metallic chassis or you'll short circuit!).  This depends on the DC supply you use.  Audio stuff uses center negative (+V on the ring) but you are using adapter that switches these (you will have +V on center pin).  So you need to connect ring to DC input (0V) and center pin to ground (9V).

In practice you can use multimeter to measure voltage between circuit DC input and ground while using battery and compare to you DC socket setup.  If it's the same and not inverted then it should work.

[shrubbery]

Sorry, hit quote instead of modify.

[macjohn]

I'm not doing any daisy chaining.  I'm using the fulltone 69 The FPS-2 Positive Center Pin adapter because it (I thought) has the same power requirements as this pedal.

So I'm still wondering... if I get a battery clip that'll hook onto my battery clip and power it and hook it into my Voodoo Lab PP2+, will that be the same as having a battery?  I assume I'd use a regular connection (not the positive center pin adapter I use with my fulltone 69 when not using the stand alone fulltone adapter)?