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Discussion Starter · #1 ·
I just received my new Infocus x1 from projectorpeople a couple days ago and have been playing around with it. As far as the image goes I was very impressed, the color, sharpness, and blacks are all much better than I was expecting. My problem came when I turned on my sound system to watch a movie last night.


From two of my speakers I got a loud hum even with the volume turned all the way down. In trying to find the interference I reconnected everything one connection at a time. I noticed the hum came back when I connected the coax digital out from the dvd player. I also noticed that the hum went away when I disconnected the component video that goes from the dvd directly to the projector. After some more fiddling I discovered that if the x1 is connected either directly or indirectly to any part of the sound system I get a hum from the speakers. The projector doesn't even need to be turned on, just plugged in.


Does anyone have any idea what might be causing this? It's very annoying to not be able to use the projector and the receiver at the same time :) I can't think of any other way to connect it to get around it either.


A couple interesting things I found while playing:

- The hum is also made when I just touch the outer shielding of the cables to their connectors.

- The projector is the only piece of equipment in the entire system that has a 3 prong power plug.


Does this mean there's some problem with the ground? How can I fix this?


Thanks so much in advance for any hints or ideas, I'm at a loss here.



Edit: After a couple more hours of investigation it looks like one possible culprit is that a ground loop has been created between the projector's ground and the cable TV's ground going into the vcr. I'll test this tonight when I get home and get an antenna ground loop isolator to fix it.
 

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It sounds as if you may have a ground loop problem. Try grounding the chassis of your other equipment to see if the hum disappears. I have all my equipment connected to a surge protector and I don't have this problem. Just attach a wire from a chassis screw on the back of your receiver etc to a screw holding on the faceplate of you electrical outlet. You may have to do this to all your equipment to isolate the hum.
 

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Beside what was already suggested, consider using

optical link instead of coax for digital sound out,

that should isolate better your components ?


My X1 does not generate any hum (beside its own

fan that is...)
 

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Discussion Starter · #4 ·
It turns out to be caused by a ground loop between the projector ground and the cable ground. Putting a ground loop isolator between the cable and vcr should fix it.


Thanks for the help.
 
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