powering multiple pedals removed from cases with 1 supply?

[rasbliutto]

hello,
I'm new, been looking through this board and haven't found an answer. I hope it might be out there, but this isn't exactly a "how to build" a pedal question...

I have three pedals, two Berhinger DD400's and one DOD FX delay (or something,,, a digital delay)..removed from their original cases, and mounted together in a box, open circuit boards facing up to be played directly. They're outputs connect directly to a mixer, they do not daisy chain together.
I have them each running off of their own power supplies because every time I have tried powering them with a single source (9v, plenty of current), I just get bleed the through the mixer they all share. My thoughts are that since I have disconnected the boards from their chassis grounds, they are forced to share the terminal block ground and bleed into each others mixer channels whether the channel is muted or not. Other than this I think all  my ducks are in a row regarding ground path for each circuit.

Any thoughts from more advanced users would be greatly appreciated. I've been using this  for years, works well, not a complete newbie, but more of an artists than an engineer so I know my approach is unorthodox.

Thanks,
R

[Processaurus]

Without seeing a schematic of your mixer connections, this is just a broad solution, but I would undo all the grounds and star ground each circuit and the mixer back at the power supply minus, and decouple the power to each circuit with their own 100 ohm series resistor (between the power supply + and the + input on each effect) and then a 100uF electrolytic cap to ground, with a .1 ceramic cap in parallel with it.  That will isolate the power between the effects.

[GibsonGM]

+1 Processaurus.    Sounds like crap on the ground line.  So you need isolation.  This is accomplished thru said resistors and caps.  In extreme cases, you can go further by 'decoupling' right at the IC sockets, too, but this 'at each board' approach is a good one....see how doing the above works, and post back - always good to know if it worked out!

Next step is to diagram the mixer connections, if this isn't enough....

~Mike