[AV_Integrated]

Issue: Lines similar to a ground loop are being generated on a LG 70" plasma dispaly due to two RF controlled dimmers in the room.


The grounds were lifted from all equipment and new wiring was tested, yet the issue remained which seems to indicate that the spark noise is being fed onto a wire other than the ground.


Speaking to others, it sounds like it may be noise that is being fed to the neutral, and not the ground.


How do I fix this?


Also: Why is it when HDMI is run instead of component video the problem goes away?


This is part of a high-end installation with cable runs of about 75 feet from the equipment to the display. Running HDMI (or similar) is not a realistic solution as retroing wires in will cost several thousand dollars in faux painting work at least.


Would a UPS bring all grounds and neutrals to a common smooth sine wave free of noise? A couple of these could be relatively easily added to the system.


How about rewiring the electrical?


What would actually put this noise onto the dedicated circuit(s) that are being used for the A/V work?


Any help and insight is appreciated!

 

[Ericthemidget]

My only guess about the HDMI is that it is a digital connections and may not be effected by electrical current like an analog connection would.


For a "high end" installation, I am kind of shocked that the system is not on a dedicated circuit and that you are not using some kind of power regulation system. I don't believe those things are a magic bullet by any stretch, but they seem defacto for high end systems.

 

[jvincent]

When you say "similar to a ground loop" how similar are you talking? If the lines are rolling, then you have ground noise. Period.


"Spark noise" would look completely different.


The reason you don't see it with HDMI is probably because there is no analog reference signal in the HDMI scenario so it's immune from the ground loop.

 

[AV_Integrated]

Yes, a dedicated circuit, yes, power conditioners in place.


The ground was LIFTED from the display and was directly fed from a DVD player via component video, and the problem continued to exhibit itself as red/blue bars running up the screen which varied in relation to the current dimming level of the lights.


Not a ground loop, apparently, but related to the noise from the spark being injected onto the neutral (possibly) of the house electrics. Potentially shared neutrals - I don't know.


I did not perform the installation, but was called in for consultation... Yet it has me a bit baffled, and I don't want to say "Run HDMI!" - only to have to convert analog sources to HDMI - with the noise still exhibiting on the component lines prior to the conversion to HDMI (= no fix).

 

[tower101]

I had a similar problem after looking for it for some time (days) found out it was coming from my laptop charger. The charger still worked fine but was causing "interference", new charger fixed the problem.


Yes I was using a "line-conditioner" but it did very little to help and the charger was on a different circuit.

 

[jvincent]



Quote:
Originally Posted by AV_Integrated /forum/post/12887362


Yes, a dedicated circuit, yes, power conditioners in place.


The ground was LIFTED from the display and was directly fed from a DVD player via component video, and the problem continued to exhibit itself as red/blue bars running up the screen which varied in relation to the current dimming level of the lights.

Were the DVD player and TV plugged into the same outlet?

 

[AV_Integrated]

As with Tower - this is occurring with the rack on a dedicated circuit and still occurs when we take the display and one piece of gear, plug them in together, and do a direct feed from the device to the display with nothing else connected.


Since ground is lifted, it is NOT coming across ground.


But, neutral is a possibility. I'm not sure who has actually had to deal with something like this who has found a solution that doesn't involve replacing dimmers or running new cabling.


Since it seems like an electrical issue, I'm trying to find someone who may know enough about eletrical to come up with a solid solution (UPS?) that will normalize the sine wave across the hot and neutral lines prior to the A/V rack.