[Tex70]

Hi All


I had my home theater installed 1 year ago by a professional and everything was fine. About 3 monts ago I started experiencing the rolling bars (bottom to top). I have read this may be a ground loop. I guess about the same time this started, they did start construction on a house next to mine and they put up a temporary power pole next to my electrical box, could this be the reason? Would a power conditioner solve this problem?


My projector is ceiling mounted and the noise is coming through the receiver because if I turn off the receiver to blue screen my projector the noise goes away.


Please let me know what I need to do or start looking at.


Thanks,

Tex

 

[trekguy]

Although you say it is the receiver it may be any of the devices that are connected to it. The coax for the cable tv service is often the cause.


It may be that the workers damaged either your power grounding connection or your cable grounding connection. If you have a grounding rod for the power you can do a visual inspection, or if you are comfortable with the idea you can ease and then tighten the connection at the rod. If you have cable or sat service check the grounding block and both coax connections.


However, post hoc ergo propter hoc, as someone is alleged to have said.


It just might be that one of your HT cables is loose or no longer making good contact. Just pull each one out and reinsert while giving it a bit of a twist.


If none of these work go by the hardware store and pick up a cheap circuit checker the kind that detect ground problems, just to ensure that you don't have a problem with the ground in one of the outlets or at the panel.


These are I think all of the cheap and easy steps.

 

[DoyleS]

Just to add to Trekguy's comments. You will need to use a process of elimination to determine if there is a specific component causing the problem. The receiver is normally the reference device. As stated above, if you have Cable TV, the incoming Cable is the most notorious offender. Try disconnecting that incoming coax cable to see if that eliminates the problem. Repeat with DVD, VCR, and all other boxes going one by one. It is likely that one of these boxes is causing the problem. Check the Hum Faq for details on how to solve various problems. Ground lift plugs are often helpful in diagnosing a problem but not recommended as permanent solutions due to safety considerations.


Since this is your first post and I really don't know how comfortable you are working with electrical devices, I need to alert you to the possible problems with different grounds. There can be significant voltages between two different grounds in a home system. In your house everything is referenced to your panel. However when something like Cable TV comes into your house, its ground system is typically referenced to another ground, be that a ground stake or some other point in the cable system. If you were to put a voltmeter between the shield of that cable and the ground pin on one of your outlets, you will likely measure a voltage. Whether it is dangerous or not depends on its magnitude. The slight phase difference between that voltage and the voltage in your house can show up as rolling bars on a video picture or as 60 cycle hum in your audio system.


..Doyle