Trouble with pedal powering... ground issue ?

[Thames]

Hi all,

I grabbed an old 80s Peavey CMC-1 Companded Chorus at the pawn shop for very low price. To my surprise, it has MN3007 and MN3101 chips in there, the same as used in the vintage effects from the late 70s to early 80s. Anyway. Plugged it in, it sounds great ! So Im making some room on my pedalboard, and as I went to play with it, bad humming, very low volume.... uh ? Works fine when used alone, but doesnt work with my other pedals. I think it has something to do with the ground or inputs. It uses a + 9VDC, but I tried it with a battery.

If some of you have a lil'knowledge about this possible issue, pls let me know. Thank you.

[DragonAX]

Is your pedal board made of metal or some other conductive material? I've had bad hum from a DOD Tec4 multiFX pedal and something else (can't remember what) used on wet grass coz current goes from case to case through the water. Can't remember if i was using a daisychain supply or not.

[Thames]

Is your pedal board made of metal or some other conductive material?

No. Made of wood.

[DragonAX]

So just to clarify, it does exactly the same thing when using a battery? and only when used with other pedals?

[Thames]

So just to clarify, it does exactly the same thing when using a battery? and only when used with other pedals?

Funny thing is, I plugged it again last nite and worked fine, with a battery, with other effects. Bad hum when used with PSU, but maybe it has no power filtering, which is not a bad deal.

[DragonAX]

Ah yeap, I think the CMC 1's do that, unfiltered power sounds as good a reason as any.
Odds are someone's plugged a standard -9v dc into it a few times and burnt out a resistor or something in the process.