hallo

a while ago i posted a thread about an audio mixer that has a faulty Schottky-diode. I replaced the diode and tested it at home and didn't noticed anything. When I went to the rehearsal room and plugged the thing in, I noticed that the enclosure started making sparks. After that the fuse of the house tripped and all power was gone.
what was the problem?
some measurements i did
the fuse of the mixer is not burned.
the chassis was connected with the ground pin of the input of the power supply
after i did this the house boss came in wondering what happened and told us that there was no ground on the electricity net in the basement (rehearsal room).
So I'm asking myself, what happened there and should we plug our instrument amplifiers on an ungrounded circuit.

i hope i made myself clear with my lousy English and looking forward to an answer

ohh and i am still alive

 

A Schottky diode is a low-voltage device. It's not likely to have to do with your current problem. Something has made a path from the mains to the chassis.

Do you have a meter? If the mixer's fuse didn't blow, the problem must be on the unprotected side. If your line cord is old, a short may be present in it, possibly where it passes through the chassis. Using a meter to look for low ohms from the line cord to the chassis may locate the problem.

If you saw sparks, there should be some signs of the problem - burn marks or bulges in the line cord.

 

If it were me, theres no way i'd be using equipment there. without a proper ground, a short or other problem can cause metal chassis, grounded stands, mic's, instruments etc to be LIVE. as in i'm holding the mic then zap i'm dead. not good.

 

The "rehearsal room" sounds like a death trap. There are multiple problems with the wiring; ie: reversed hot/neutral and no ground. Don't plug your equipment in there again until they get it fixed.