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[juancaminos]

I have a Yamaha 16 channel mixing board for live use but also use it at home. It came with a two prong plug, no ground. It actually has a box/transformer between the plug and the mixer. At one particular bar we had issues with noise thru the pa as well as shocks at the microphone. So we tried different stage plugs to no avail. Then we tried plugging everything into one outlet but that blew the breaker and pissed off the owner.

Then someone told me of this trick. I got a piece of wire with an alligator clip at each end. I would then loosen the screw that held the 120 outlet face plate on and clip one end of the wire to that. The other would clip on to a metal part of the board. It worked!

Is this good or bad? Why would Yamaha market a system with out a ground lug like that?

 

[Stumbo]

@agedhorse would know.

 

[agedhorse]

The grounded power cable is used for 2 purposes, for safety and for POSSIBLE reduction in noise.

When an ungrounded power cord is used, an additional safeguard must be designed into the power system to protect against shock in the event of a single fault type failure. This is typically called "double-insulated" construction in this application.

For noise purposes, this only works in some cases and can make the noise worse in other cases. In general, it can't hurt anything as long as the receptacle is wired correctly and the screw is really bonded to ground.