On stage live...I want to use the B205D as a personal monitor...the band uses a Yamaha EMX512SC 8 powered mixer on stage...What would be the correct connections to hear only my vocals in the B205D monitor but still be heard in the Mains.

Fixya does not sell anything. You need to contact whoever sold you the item directly to ask them about when/if it was shipped.

Because the power supply is breaking down and needs to be replaced.

An external equalizer will not help this at all. The problem is likely within the amp (feeding the main speakers), the connections from the board to the amp, or the speakers themselves. In other words, the answer would be "NO." Best of luck!

Make sure that the Player is set to iPod mode and not AUX.

Do you mean there is no sound coming from your monitors? Check whether you've accidentally diverted the main-mix signal from main-out (or whatever you have your monitors plugged into). Can you get a headphone mix?Also, dumb question, check that nothing is soloed!

Because it is solid state for one.

It is also a Class D type amplifier, so the 500 watts is only a a peak rating and not very accurate, it is not an RMS rating, there is a big difference.

Class D amps chop up the music stream so it is not a continuous signal like analog signals are. It has a generalized block diagram similar to a power inverter or an AM transmitter. You ear is not likely going to notice the difference.

Watch videos on YouTube about proper setup of a mixer/amplifier. Proper level setting at the different stages of the mixer is important to balance. You don't give us a clue as to what music you are talking about... if it is from a device plugged into the tape inputs for instance, the fault is your source is NOT providing adequate line-level to those jacks and you are trying to compensate with the master level. The master level should probably be around60% up in normal operation.

What is the make and model and i'll find you an owners manual for it

Chances are there is nothing wrong with the mixer. IF you accidentally turned on Phantom power, that would cause the problem. Phantom is ONLY used with condenser mics and a few DI boxes. Turning it on can create noise unless balanced lines are used everywhere.

That might be correct.