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Really at the end of my rope here. I went to set up at the bar I do my weekly Friday night show at last night and couldn't get the tvs hooked up. Every time I hooked their coax up to my system I got a massive hum, and actually damaged my mixer, and now my video out jack on my triple tray too. Actually have an electrical current going through it when I tried to hook up. Any ideas? I tried about every configuration I could think of, but the only thing I can even begin to guess is a bad ground in the wall outlet. Any suggestions are appreciated.......Jim

Are you hooking their co-ax to a modulator? Cant understand how it damaged your mixer unless it isnt grounded and there is a voltage on the co-ax ground..

Their antenna system must not be grounded even at the dist amp. There is a tv plugged in wrong or bad and you have voltage riding on the co-ax . Dont hook up to it until they have the system checked out. Have they had problems with a hum bar floating up or down?

I would also check the outlet you are using.

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Really don't think it is coming from the coax, but using the coax for a ground. I tried eliminating the equipment one at a time but still had problems. Concerned about the outlet myself, or even the entire cicuit, because I did try another outlet.

Without more info I'm just guessing. Hum in the audio or video?  Does the modulator have a grounded plug? Is it an old bar? Have they added anything to that circuit?

Need a basic description of system and how it is hooked up.

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Don't think it hurt your mixer, but definetly eliminate any other signal source going into any video display source you are using. You can use a video game switch to block the feed, or just unplug it. Even if the cable tv is connected to a different input on the tv, it will still loop back into your system. There are filters you can buy, but this is the easiest thing to do in my opinion.

Thanks for the help guys, turned out to be a bad wall outlet with no ground (gulp!). Bar is going to replace all my fried equipment, wound up blowing up two mixers, my beloved triple tray, and my dual CD player. The live side of the outlet was in direct contact with the metal wall box, sending current through my ground line directly to my rack. A voltage tester showed 80 volts on top of my mixer, and 110 on the outside of my Furman power conditioner. Guess I can thank my lucky stars I didn't get hurt.

Older buildings are often times not wired to code with proper grounds. As big coolers etc are added the phase load can become unbalanced which causes problems with digital equpitment. HP discovered this in their IC processing labs. Any outlet in older bars should be tested with this

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Looks like something every mobile equipment operator should have with them... sure could save a heap of potential gear fry!

I had a somewhat embarasing problem last week where I did have a slight "humm" in the background. I have known about such problems caused by long wires, intererence, bad powere etc as the other posters suggest, but for me the problem turned out to be more simple.

I had an extra mic that was for the KJ to make announcements, and I had recently rearanged my setup and it was sitting next to the external hard drive unlike it was previously. Sure the hard drive was quiet, but it was close enough to the mic to amplify and pick up the noise, only after amplification through the sytem was it loud enough to be noticed. I tend to keep the KJ mic on high gain so I can talk normally for announcing, so that added to the problem. I moved the mic a grand total of 6" and the problem went away. But it took me the better part of an hour to figure out the cause.