T.V. Interference

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electricmanscott

electricmanscott

Senior Member
Location
Boston, MA
Just got a call about a receptacle I installed last week for a Plasma TV. Seems as though when the lights in the room are on there is a green line that moves up through the screen.

That is the description I got and I haven't seen it for myself so that's the best I can explain it.

I also don't know what kind of lights they are, or what controls them.

Any thoughts??
 
brantmacga

brantmacga

Señor Member
Location
Georgia
Occupation
Former Child
Q: Why are there translucent scrolling horizontal bars on the screen?

A: These bars are commonly known as "hum bars." One cause is that the source and monitor may not share the same electrical ground – instead, they are plugged into separate electric lines grounded on different circuits, or the cable wire itself is not grounded to the same conductor as the unit’s ground. Sometimes battery-powered images sources (camcorders, laptop computers), which share no common electrical ground with the display, introduce the hum bars. Try using the source device’s A/C adapter instead, plugged into an outlet grounded to the same conductor as the Plasmavision display's power cord.

Another cause of scrolling hum bars is signal wires run next to A/C current wires. Take care to separate these two kinds of wires. If they must approach each other, arrange the wires so the signal wire crosses at right angles to the A/C. You may need to contact your installer or qualified electrician to fix this problem.

A third cause of hum bars is a strong motor or other interference-generating, power-hungry device which shares the same electric line as the plasma set or video signal sources.
 
G

got_nailed

Member
I think it?s time for a over priced surge protect that clams to; ?Monster's PowerCentersTM featuring Clean PowerTM filters protect your components from noise for a cleaner sound and fewer video artifacts. Monster's AVS 2000 Voltage StabilizerTM delivers a steady 120 volts to your system for greater dynamics and more focused sound. Damaging surges and spikes can enter your home theater system from your video cable lines coming from an outside source. Make sure to connect them through a Monster Power? PowerCenterTM.?

http://www.monstercable.com/connection/guide_cleanpower.asp
 
brian john

brian john

Senior Member
Location
Leesburg, VA
Why is this your problem? I would tell them to call the TV manufacture...
__________________
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IMO and in my expierence this is a LOUSY approach to business. NEVER, NEVER, NEVER assume it is not your problem investigate and prove it is someones else problem. If the TV guy for what ever reason proves either through true investigative procedures or BS'ing to the customer your install is wrong, you will look like a slacker haphazard electrician and perception can be everything.

I have been hired numerous times to check out issues between electrical contractors and GC's, AV, TV and studio types, I have had to make electricians look bad as they argued in meeting with me regarding why their installation is correct. I do not like this and would never want to be on the receiving end of a lesson in electricity in front of a customer.

Check it make sure it is right and then sleep comftrably
 
quogueelectric

quogueelectric

Senior Member
Location
new york
Brian is correct

Brian is correct

brian john said:
IMO and in my expierence this is a LOUSY approach to business. NEVER, NEVER, NEVER assume it is not your problem investigate and prove it is someones else problem. If the TV guy for what ever reason proves either through true investigative procedures or BS'ing to the customer your install is wrong, you will look like a slacker haphazard electrician and perception can be everything.

I have been hired numerous times to check out issues between electrical contractors and GC's, AV, TV and studio types, I have had to make electricians look bad as they argued in meeting with me regarding why their installation is correct. I do not like this and would never want to be on the receiving end of a lesson in electricity in front of a customer.

Check it make sure it is right and then sleep comftrably
Click to expand...
Check that the component video leads are all pluged in completely they can get pulled out durring the install and cause this type of problem.
 
S

S Gordon

Member
We had a similar situation years ago and the same thing, well almost, happened. At this home* it was whenever lights controlled by any dimmer were turned on. Turn the lights off and see if the line(s) go away. If so see if the cable is ungrounded. It was at the home* we worked at. Someone had unhooked the main ground outside hooked to the electric service.

*referred to as a home and not a house because people live there. People who paid me to do work and weren't turned away when a problem arose, even though it wasn't our doing. That homeowner has had us out at least once a year for the past five years and referred tons of friends.
 
B

bakerbrotherselectric

Member
T.V. Interference

We solved this very problem a few months back. Here was our experience:
  • Clamp on ammeter on cable demarcation point ground was showing .9 Amps continuous!
  • A 1000 Watt dimmer had 1800 Watts connected to it and when in use, was hot enough to cook eggs on it.
  • There was no ground rod driven into the ground.
  • Circuit breakers were barely making contact in the panel.
  • The neutral bus bar was over loaded with many wires under each screw


Here were the steps we took that solved the problem:
  • Unburdened the 1000 Watt dimmer by replacing bulbs with lower wattage bulbs
  • Drove a ground rod
  • Replaced the faulty breakers
  • Added a neutral bus bar

We suspected the dimmer might be using the cable companies ground path which was bleeding through the AV gear. Since the neutral path was poorly done we figured at higher amperages the house was using alternate grounding paths. The over loaded dimmer was the biggest contributor to the problem. At first we thought maybe the remodeling company improperly shared neutral paths but it turned out the mega over loaded dimmer was causing most of the issue.

Hope this helps.

KB
 
D

danickstr

Senior Member
i have also noticed that if all electronics are on the same leg at the service this can eliminate weird hum issues. not necessarily the same breaker, just the same phase leg.
 
mdshunk

mdshunk

Senior Member
Location
Right here.
bakerbrotherselectric said:
We suspected the dimmer might be using the cable companies ground path which was bleeding through the AV gear.
Click to expand...
I've read this sentence three times, and I still don't understand how that could ever be.
 
brantmacga

brantmacga

Señor Member
Location
Georgia
Occupation
Former Child
i have also noticed that if all electronics are on the same leg at the service this can eliminate weird hum issues. not necessarily the same breaker, just the same phase leg.
Click to expand...

yes that is true.
 
brian john

brian john

Senior Member
Location
Leesburg, VA
Two words HOODOO VOODOO....

I just completed a grounding investigation on a massive church that had excessive hum issues. Dimmers all over the place not the issue (but with some dimmers I would not rule this out). Ground rods missing NOT THE ISSUE. I have completed numerous Grounding Investigation and to date all were related to improper neutral grounding or cross connecting neutrals from 2-different separately derived systems.

I am sure there are other issues that may cause hum, but the lack of a ground rod is NOT ONE OF THEM, in my expierence.

IMO it is prudent to have designated panels separating AV equipment from other loads as it can minimizes some problems, I have seen some electrician nightmares in major studios that worked find after the neutral ground issues were resolved.
 
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quogueelectric

quogueelectric

Senior Member
Location
new york
dimmers

dimmers

mdshunk said:
I've read this sentence three times, and I still don't understand how that could ever be.
Click to expand...
some small electronic devices like dimmers and motion sensors have such high impedence electronics that they use the ground for the return path for the electronic control ckts. This will produce small almost negligable currents on the ground wires which are all common to every wire in the electrical ckt on the return side of the loads.
 
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