I've been involved with my church's sound team at different levels of responsibility for the last several years. I've always suspected power issues (due to the number of hums, buzzes and audio units requiring servicing) but could never authenticate my suspicions. I would test the wall AC outlets and everything would appear normal. However, the Furman power conditioners have a "Ground OK" LED that was not lit. Today I had one of our electrician/musician members meet me at the church to investigate a little further. What we discovered was that our two Furman power conditioners were wired out of phase. The factory plugs had been removed and in their place were Leviton plugs (off the shelf Home Depot variety). Hot was wired to neutral and vice versa. I spoke with our worship pastor to see what the deal was and how long we have had those power conditioners. The answer: at least 15 years! We've had problems with compressors and preamps going bad since I've been there. I think I know the reason why now.
We've rewired the connectors properly, the "Ground OK" LEDs are lit now. However, I'm concerned about the state of the equipment that was connected to said power conditioners (Allen & Heath GL3300, various compressors, EQs, QSC power amps, crossovers, wireless receivers). Is there anything I should be looking for / suspect of when assessing the condition of our equipment?
Just go through and make sure that things are wired correctly, patch bays, cables, adaptors etc, you wont have to do everything just a few spot checks.. open the connector up and have a look.
I recently had a job in a theatre with hum in the system ALL the XLR-XLR leads were wired with the braid of the cable on pin 2 of the connector (on a tester they checked out fine) but caused MASIVE problems.