So I sold my Ecler and since I'm now mixerless I dug out this bad boy again, needless to say the problem is still apparent.
but: I have found out some new things. the power supply is good. I sort of suspected it, it looks like its from Soviet Russia (massive piece of brown plastic).
I took an old wire (the old earth cables from my technics) and hooked them up on one end to the ground post on the mixer. Then I touched the rec outs (RCA) with the other end of the (stripped) cable. The hum instantly dissapeared, sound wise and also from both the master level meter and the PFL level meter (which was set to a mono output, sort of like the master).
Now If I took that wire and touched an rca connection with it near the master section ( main mixing channels are left and right of the master section) the hum also disappears. But If I touch an rca connection further from the master section, like channel 6 or something, the hum silences somewhat, but doesnt disappear.
Now I could rig an RCA cable so its permanently connected to the ground post and rec output, but there must be a way to fix it for good.
Another question: the capacitors look quite shoddy, with some brown goo on them. Could it be that theyre blown and they cause the problem?