M200 Hum and satellite dish

I set up my M200s for the first time last night and found this nasty hum. I worked backward from the speakers and found the hum faded about 90% when I unplugged the S-Video cable between my HT receiver and satellite dish box.

The hum remained when I pulled the power plug from the satellite and left the S-Video cable connected. So, I figure there is a ground loop issue with the sat. Question is, how do I fix it? I have found plenty of info on ground loops with cable boxes, but not for sat!

Thanks-
Xant

Is there a ground screw on the back of your reciever or 200? Try running a wire from the Sat coax cable metal sheild to the chassis ground of your receiver and see if this helps reduce the loop. Disconnect the sat coax cable also and see if the hum persists. Then you will know for sure it is a result of the coax cable and not the s-video.

Otherwise, in the Outlaw 770 manual, I know they have a section dedicated on how to remove ground loops, try those steps as well, the 200 manual might have the same data.

After a conversation with Scott, I've ordered a pair of Xantech Ground Breaker (their part # 634-00) to isolate the ground from my dish coax cable.

After a few more hours of plugging and unplugging components without luck trying to get rid of the last bit of hum, I got up and went to the kitchen for a drink. I flicked on the kitchen lights using the DIMMER switch. BOOM light goes off (in my head). So the last bit of hum is coming from the 1000W dimmer in the kitchen.

Any idea how to get rid of that hum without replacing the dimmer? When I unplug the TV, it stops. Go Figure. Guess the TV tube is the interacting with the dimmers field?

Rob

I poked around a little bit on google and found a few links , but nothing real definitive. You may be able to track down a different type of dimmer switch and eliminate or at least significantly reduce the hum it is introducing into the house electrical system

UPDATE- As per Scott's advice, I bought 2 "Xantech 634-00 Ground Breaker" isolators for $18 shipped from a buglar alarm retailer called Bass Home . Since I have two tuners on my DirecTivo, I got one for each feed.

These things are cheap as heck and work as well as those Jensen models that are 5 times the price.

I am happy now. Thanks Scott. Hope this helps someone!

Rob

Update Update- I am, again, sad now. The Xantech's not only fixed the hum, but they also stopped the sat signal cold. I didn't notice it for a day because we were watching Tivo'd programs. The live feed was dead, I found out the next morning.

Crap. Any other idea's Scott?

Best-
Rob

Hello Xanteen,

That directly contradicts the information I was given. Hang in there for a day or two and we'll figure this out.

Scott

AH! I think I know why you're not getting sat feed.... the reciever sends power (DC) back up the coax to power the LNB's... So, breaking the ground is also disconnecting the negative side....

hmm....

Do you have anything else between the dish and your reciever? (multiswitch, etc?)

Are you grounding the shield of the coax going into your house from the dish anywhere?..

Yep- I am have a grounding block inline with both runs. That's all that is between the receiver and the LNBs. So, I am guessing you are right, that the LNB's aren't getting any power. I didn't know they needed juice. I figured that LNBs were passive, but that's why I ain't no rocket scientist.
Thanks-
Rob

Bueller?

So.. what's the status of it now? Do you have the grounding blocks taken out? If you ground the shield of your coax to the lnb's do you still have a noise problem?

edit: by ground the shield of the coax going between the dish and your reciever I mean to the earth somehow (water pipe, ground rod, etc.)