Strange Problem with my actual build

[Harmony-Rocket]

I 've got a strange problem with my actual build (stone grey distortion).

Every time i connect the fx to power the tone comes loud and clear....
but only for a second (and only at max. gain and level) than it vanishes,
ending in a VERY small level????

I did the usual things i can do (checking the board, turned the trannies etc.) but cannot find a fault.

Thought of a capacitor (elko?) is broken but I have not much knowlewdge about electronics, so it seems  best to me to resolder everything...
(w.c.s).....

Perhaps this is an easy issue and someone can give me a quick hint ?

[Madferret]

Are you using batteries or a power adapter?  Could be a dead battery.

[Harmony-Rocket]

No batteries, just 9v power supply ( I am using a royal t-rex chamelion :O) - I think it is not dying ;)