As you know I picked up a Samsung 50 inch plasma a bit ago. I have been having a ground loop problem with the set since the day I got it. Humming and ground bars scrolling through the tv. I called Comcast about the problem and they sent a tech out to look at the cause. Well they changed the ground wire on the outside of the house and still the problem exists. The tech said it's a house wiring problem and for me to figure out how to eliminate the hum.

I knew what I needed before the tech ever showed up. I ended up ordering the Axiom ground isolator. It came in today and within minutes the humming and ground bars were eliminated from the set.

It's well worth the money to get rid of that dreaded hum.

Thanks again Axiom.

sorry your having problems Rick, can't help much on advice.

free bump

I got a ground loop from my BFD and I couldn't believe how easily that problem was fixed by the isolator, when nothing else that I tried worked for about 2 hours before it.

Not any more Randy.

Oh, you know Randy's just aiming for that 10K.

He's getting close

Where does this device go? Cable feed to the home?

I put it inline on the cable feed going to the set top box.

I was going to order one from Axiom a while back until I found out that it could not be used with a satellite dish.

What was your favorite frequency of ground hum?

No more humming at Wid's house. Glad to hear that you got things fixed Rick.

Very good, Rick. Sure, it wasn't that there was something defective about the cable ground that could be corrected by changing it, but that the voltage potential beween that ground and the other ground in your system was big enough to cause a current to flow and cause hum/interference. The isolator cut the hum signal without affecting the TV signals.

Incidentally, Dr. Horse mentions a point that seems rather curious, since the claimed 1.5 GHz bandwidth would be adequate for the down-converted satellite signals. Wonder if a problem really would exist.

Hi JohnK,

The bandwidth isn't the problem with satellite signals. It's that the satellite receiver sends a voltage to the dish antenna to power the feedhorn for the dish. Axiom's ground isolator would interfere with the phantom powering of the dish's pickup.

Kind of like phantom powering of some microphones from the mike preamp in studio and remote recording.

Regards,

Alan

Thanks for the explanation, Alan. I wondered why Axiom might be limiting the sales of their excellent isolator if it could in fact pass the roughly 1 GHz incoming satellite signals. A less obvious problem, but one that still makes it unsuitable.

I have a hum I recently noticed from my bedroom SD Comcast DVR box(Pace TDC577X). I imagine the DVR has a spinning disk, but funny thing is it hums when it is OFF too. Probably totally unrelated to your issue, but since you guys were talking about humming, it reminded me of my hum.

Dave,

If you mean the whirring of the DVR's hard drive, no, that never shuts off when you turn off the DVR, only if you unplugged the unit.

If it's a ground-loop hum you are hearing through the speakers or subwoofer or the TV's speakers which is caused by the cable-TV input, that too will continue whether the DVR is on or off. That would disappear if you turned off the TV, subwoofer or AV receiver, which amplify the ground-loop.

Regards,

Alan

DVRs are notorious for spinning their disks even when "off" (standby). They can't really be off, because they need to power themselves up in order to make scheduled recordings, and also to update their guide information.