noise when using dc jack?

[bagudan]

Hi. I had an old vox 847, that i modded to the great sounding axis wah from the fuzzcentral site. Yesterday I installed a dc power jack, and suddenly it became quite noisy in the toe-down position. I removed the power cable an used the battery, but still it was a bit noisy, from the power cable in my boost-pedal (earlier in the chain). When this cable is removed also, it is not noisy. My power supply is a well regulated supply...?
Is a dc jack no-go with an old v847?

[GibsonGM]

Might be a no-go...wahs, in my experience, don't eat batteries (I change mine like once every 8 mos., and play out 2-3 times a month).  But, there are schemes you could try to reduce the noise from the power supply, such as putting a cap across the power supply terminals at the DC jack (try 47pF, 150pF and so on until you get a result - or not).   This is HF noise riding in on the PS, pretty common problems.   Another thing is to add a 100R resistor in series with the + line, followed by some form of filtering cap (value TBD by experiment). 

Also, try searching "power supply noise" or "noise" on here, there should be a lot more info.

[bagudan]

thanks... I´ll try fiddling around with caps tonight

[bagudan]

Tried thousands of different cap/resistor combinations...no luck. But when using another dc cable from the power supply, suddenly the hiss/hum dissapeared. Funny thing is, that the "noisy" cable, it not at all noisy with other pedals? but hey! who cares. I have a noisefree wah
Thanks for the help though.

[aron]

This is a tricky one. When you use a battery it is still noisy? Maybe the noise was coming from an earlier pedal in the chain when the two were daisy chained off of one supply? Just guessing.

[bagudan]

I think you´re right Aron. When removing the power chord from my booster/buffer(1.st pedal in chain) the noise dissapeared(when using battery to power wah.
But somehow, with a new powercable, everything seems to be in order? The only thing that bugs me, is that theres notning wrong with the old power cable, at least not with other pedals.