Okay. I have a cable box that is run to my projector. audio is then run from the projector to the bookshelf unit for sound. I’ve got a ground loop causing a low hum, and occasionally a horizontal bar rising up the screen. The source of the loop is the cable. I don’t want to spend money to resolve this issue. I also don’t understand any of the various sites talking about impedance, ohms, multiple earth points etc… Can someone please explain to me in plain english what is happening and a simple way to resolve the problem? It didn’t always do this either. it started randomly one night and hasn’t stopped since.
Hmm… the way we try to minimize ground loops at work is to have our circuits connected to ground at a single point. I think for a residential/electronics situation you would just want all your electronics plugged into the same circuit… Meaning, if you go to your breaker box, a single switch would cut off your TV, projector, and audio amplifier because they are all on the same circuit in your house.
They are. Everything is run on a power strip. I’m considering changing the strip to a larger, protected type box unit I have.
Carnivorous plant, I tried running a wire from the metal imputs in the manner you suggested. Nothing happened. Do i need to find another metal point to attach to?
Something I’ve done in the past is to take two baluns back-to-back to isolate an incoming cable.
This also will take care of DC on the line or floating shields - I’ve been “nipped” more than once from coax with bad grounds - they pick up stray currents and the next thing you know, there’s 60 volts on the shield waiting to bite you as soon as you unscrew it from something with a decent ground.
I suppose you could try connecting the shells of each signal cable together using alligator clips and copper wire… and if your amplifier has a ground screw on the back, you could also try connecting your shells to that.
Call your cable company - if this just started, they may have messed up a ground at a junction box.
I can confidentially say that there is no way to rectify this problem without a ground-loop eliminator (transformer) in the cable. I had this problem, and was able to reduce it substantially by driving a ground rod into the ground where the cable entered the house, and grounding the cable to it, but it didn’t fix the problem completely. The only way I was able to cure the humbars was to buy a in-line transformer.
Ah! Now that could well be the issue. When we first got the box, we got a lot of free channels we were not paying for. Now that I think about it the hum started around the time they “fixed” that little issue. (going out to check the ground connections)
Not that I know of. The house is older though and has been remodeled a few times. it could just be a function of the wire i used. I didn’t have any
large gauge copper so I used some tie wire.
best practice is to have cable tv coax (at the point of entry into the house) go into a grounding block which is connected to your house electrical grounding system (at the grounding electrode point) with 10AWG wire.
You can get a little bit of hum by a cable picking up 60Hz from the AC power wires. Both the power cords and the AC wiring in the walls of your house broadcast 60Hz, and a cable can act as an antenna to pick those up. Especially if the cable is longer, or in close proximity to power wiring. Cable shielding, twisted pair, etc. will help reduce this.
thanks guys!