Ground Switch

[guitarfreak12]

I was helping my father-in-law fix his system in his church. He has an old Peavey pwerd mixer, the fuse was blown. I looked at the back, and there is a switch on the back. A three position rocker switch. +, -, and 0 is the middle postion, apparently someone put it on the + and it blew the fuse. OK, now the letters next to it said "ground". I've been an electronics tech for 10 years, and it's obvious now that I haven't seen everything.....What the crap is this switch? My first thought was a ground lift, which would make sense, but not a 3 pos ground lift, and one position that blows fuses!!!

 

[boingoman]

It switches which leg of the AC the neutral is hooked to, with center off. Potentially dangerous if 1) left in the center position, with the safety neutral disconnected or 2) set in the wrong way. Setting it the wrong way creates a path from positive to ground (short) through any equipment connected to it that is properly wired. That's how people get zapped by mics while holding guitars plugged into amps. Either the socket is miswired, or the switch is set wrong.

Best idea is to remove the switch, hardwire the thing correctly, and check the AC in the building to make sure it is all correct.

ps- if the mixer is not hooked to any other gear, it shouldn't blow fuses no matter what position the ground switch is in. Something is wrong with it in that case.

 

[guitarfreak12]

ok, that makes sense, but the fuse that was blown was the mixers main fuse, not anything else.