grounding issue

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Eat Spam before it eats YOU!!!
Member Since: May 11, 2002

My church might have taken a lightening strike as we developed a number of oddities in the PA system all at once. I have it 'functional' but would like some ideas on tracking down the bad grounding.

The main concern appears to be loss of proper grounding because the left channel was playing radio stations and was remedied by adding a ground lift to the PA controller (dbx driverack) ...it plugs into a Furman PL+

Should I expect the entire building/or at least fusebox to lose ground or does this usually manifest itself in individual components? I ran a 100ft extension cable across the building to a different outlet and still had the radio stations

Is there a method for testing ground?

Some of the other problems that seemed to have shown up were
1. a bad cable out of the PA controller to a XLR wall socket
2. Crackling in one powered speaker (seems to be a very dirty volume pot)
3. one powered speaker has extremely low signal (might be a cable issue)

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The Czar of BS
Member
Since: Dec 31, 2007

Jul 15, 2009 07:37 pm

Hummm...... This is going to require some thought..

The Czar of BS
Member
Since: Dec 31, 2007

Jul 15, 2009 07:53 pm

I think that you may have the ground and neutral bonded somewhere in the building.

And the radio station has to be very close by.

If your church is using a one ground strap straight to Earth, then a lighting strike could do that.

One thing that I think that you might want to try Zek, is to find the fuse panel that your system is running from.

Remove the bonding strap, and ground wire. Cap the ground wire, and see if you can find a water pipe close to the fuse box.

Run a wire from the ground lug of the box to the water pipe. The thicker the better. At least an 8 gauge or 6.

See if that helps. Because it does sound to me that the grounding point of the building did disappear. And if it is bonded to the neutral, that would give you the antenna noise that your talking about.

The one way to test the ground, is just to meter it. Hot and ground. And compare that to the reading between hot and neutral. The reading should be the same. Any difference would indicate some ground fault.

Also read between neutral and ground. If there is anything above a half a volt, this would give you a hum or a buzz as well.

Localizing the ground should help eliminate most of your issues.

> > > grounding issue

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