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grounding advice sought


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2 replies to this topic

#1 of 3 OFFLINE   John Walker

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Posted June 09 2003 - 12:18 PM

None of my equipment is grounded; they all have just the two prong plugs. I've often thought (both this equipment and previous stuff) that it should be grounded. (I notice pretty decent static discharges when I touch the body of the receiver etc.)

I've read about "floating" grounds on IC's and I understand that is reference ground not chassis ground, but shouldn't this stuff be chassis grounded? Or should I just rely on the cable TV companies coax (foil) shield to ground all my A/V equipment (yikes!). I could add a wire from a chassis screw on the back of the receiver body to the AC ground etc (who knows there may even be a ground screw).

PS I've been reading on surge suppressors etc and the good ones make a point of monitoring line-to-ground, neutral-to-ground, and line-to-neutral. Does this still work if the suppressor is plugged into a grounded outlet but none of the appliances have three prong plugs?

Thanks in advance

John

#2 of 3 OFFLINE   Bob McElfresh

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Posted June 09 2003 - 12:25 PM

You only need a ground on POWER devices like your receiver or self-powered sub. Your line-level devices (DVD, VCR, CATV box, Sat Receiver, etc.,) dont need it.

In fact, it's a PROBLEM if you have more than one ground point because it causes a ground loop. This happens a lot with a receiver (with a 3-prong plug) and a self-powered sub. A special subwoofer cable is sometimes needed to break the connection.

Your electronics do share a common signal-ground. The 'shield' on your interconnects gives all devices a zero-volt reference.

#3 of 3 OFFLINE   Glenn Overholt

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Posted June 09 2003 - 02:59 PM

Two-pronged equipment doesn't need a ground, so don't worry about that.
However, if anything is connected to the receiver that has a ground (like any interconnect) and it goes to a piece of equipment that has a ground plug and it is not on the same circuit as the receiver, it may cause a ground-loop, as you said. This can sometimes be fixed by running a wire from the ground terminal on your receiver (just below the antennas for the radio) to a screw on the wall socket.

Do not depend on CATV grounds. They may have hooked it up to your house and put in their own ground, or none at all, and this will start up another ground loop. I have seen CATV with no ground and a 2nd ground for the house, which will make a mess of things. Of course, if everything is ok, don't touch a thing!!!

Glenn