I have a Yamaha IM8. I had a condenser mic hooked into channel one with phantom power on. I had to leave the room for a while and when I came back, I noticed some rather severe popping in the audio. I turn off the phantom power, change to a different condenser, turn phantom back on and this mic will not pass any audio. I turn off phantom power, connect a dynamic mic and I do get audio. It sounded raspy at first, but soon smoothed out. The power supply indicates that it's 48 volt output is fine. The first condenser mic may have problems like a flaky connection across the phantom circuit. Hope the board's not damaged. Whats the word on that? Thank You.

There is really no way for a condenser mic to damage the board UNLESS you break the ground and get a static discharge into the input. That can happen with any microphone and has NOTHING to do with the phantom being on or off. As phantom power goes on and off slight bias at the input preamps can make amps non-linear causing the raspy sound you heard. The Phantom LED means NOTHING as it shows the state of the phantom switch by connecting a 12 volt source through a resistor to the LED... It shows NOTHING regarding the state of the 48 volt supply. Each input circuit has two 6.8Kohm resistors to the swinger of the phantom switch 2nd pole that either grounds those or connects them to a filtered 48 volt source. As long as you don't have a static buildup there is NO need to turn phantom power on or off while connecting a condenser microphone. At each input when using the XLR jacks are two per side 470pf capacitors for RF bypass. For the XLR's there is a 10Kohm between the signal lines and two series 10mfd/50 volt caps in series of each input to block the DC, when using phantom power, from reaching the preamp stage. These caps have to charge and discharge when changing the state of phantom power so you should AVOID having the main amps being driven while changing the state of any phantom power. Always have the fader(s) down and any monitors down to avoid a thump and also the non-linear raspy transition as the input caps charge/discharge. So fix the microphone... don't know what type you have, but DO check the cable (first) as ALL three conductors MUST be good for a condenser mic to work on phantom power. A ground leakage or noisy connection will cause your symptoms. Use a SHORT known good cable right at the board to test the mic. The 48 volts is applied through the two 6.8K resistors between both the signal lines to the shield of your XLR cable. The microphone picks off the 48 volts with a similar circuit.
Now let's cover a very important thing regarding system safety: ALL, and I do mean ALL interconnected equipment MUST be powered from the same source. Professionals run a power cord back to their mixer right alongside the snake. This is to avoid ground bounce damage due to bad building grounds or ground faults.