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Groundless Laptop
Old 07-03-2008, 07:49 PM   #1
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Groundless Laptop

I've been recording online videos (e.g. Hulu - Watch your favorites. Anytime. For free.) from the computer to the DVR. There was a 60 Hz hum in the audio, and from some Googling I found that I could eliminate it by using a three-prong adapter, that is, by eliminating the ground on the plug (ground loop info).

I don't see any significant risks in running the laptop ungrounded, do you?
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Old 07-04-2008, 12:12 AM   #2
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I don't see any significant risks in running the laptop ungrounded, do you?
Ungrounded should be fine. But don't make it un-earthed, lest you be killed in a very prim and proper way
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Old 07-04-2008, 10:19 PM   #3
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One extra precaution - unplug the laptop power, then connect the video/audio cables to the video/audio system. Then plug the laptop power in.

Just a little extra insurance, in case the laptop 'floated' to a higher voltage above ground. If that happened, it would be the cable connection that would suddenly bring the laptop back to ground potential. That could put a bit of a zap into the laptop, or the audio/video system.

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Old 07-04-2008, 10:43 PM   #4
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Just dont stick it in the water

Sounds like you have a ground loop or an invalid earth ground.

Beyond that is a speculation about your cable companies installation and short and rusty ground rods.
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Old 07-05-2008, 01:56 AM   #5
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They run fine without the ground. In some places in Asia, the chargers don't even have the third (grounding) prong. I bought a Sony Vaio for DW that doesn't have one. In fact, even if it had a third prong, there are lots of buildings here that do not have a receptacles that accept the grounding prong. I'm running my US bought Compaq right now without one (using an adapter) because there is no place to plug it otherwise.
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Old 07-05-2008, 08:31 AM   #6
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Originally Posted by TromboneAl View Post
I've been recording online videos (e.g. Hulu - Watch your favorites. Anytime. For free.) from the computer to the DVR. There was a 60 Hz hum in the audio, and from some Googling I found that I could eliminate it by using a three-prong adapter, that is, by eliminating the ground on the plug (ground loop info).

I don't see any significant risks in running the laptop ungrounded, do you?
I'm assuming you wouldn't be doing this during a thunderstorm?
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Old 07-05-2008, 09:35 AM   #7
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I'm assuming you wouldn't be doing this during a thunderstorm?
Probably should avoid plugged in electronics in a thunderstorm anyhow, but not any more/less dangerous w/wo the ground on the laptop PS.

The end result here is that the laptop *is* grounded. It is grounded through the audio/video cable ground. What he is doing is avoiding two grounds, which can cause the ground loop problems he linked to.

I'd assume that T-Al has run into this problem with his band? I seem to remember that some of my old amps had a 'ground lift' switch, for this exact purpose. But you do need to make sure that no outlets have hot-neutral reversed. That can be exciting (and deadly). Hands on metal guitar strings, lips to the metal wind screen on the mic - ouch!!!!!

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Old 07-05-2008, 10:51 AM   #8
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Chasing ground loops can be frustrating, often there is a ground loop between tv, DVR, Cable from street side to equipment. A frequent help is to isolate the cable with "balun" fancy name for for a transformer. Two of the 300 Ohm to 75 TV transformers connected with their 300 Ohm leads together, connected between cable and tv will kill one ground loop.

Cheching for hot/neutral reversals is important, as noted by others. Floating a laptop from house ground should be no problem.
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