DSS Ground loop?

Discussion in 'Playback Devices' started by KevinB, Mar 20, 2005.

  1. KevinB

    KevinB Stunt Coordinator

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    After a complete remodel of my home theater, I have an irritating problem. When I hook my Directv system up, I get a loud hum through the speakers. It goes away when you unplug the component cables and the satellite input cable. I have search the forum to see if the devices that work for cable (ground loop isolators) will work for DSS, but haven't seen a definitive answer. Anyone know or can tell me how to break this ground loop? Thanks, Kevin
     
  2. Kevin C Brown

    Kevin C Brown Producer

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    I will find out this Fri. [​IMG] I'm switching from cable to a dish, and one of the things I will check out before the guy leaves is for a ground loop with my system.

    Your experience echoes mine: I see all kinds of isolators for cable, but not too many that specifically say they work with a dish.
     
  3. Wayne A. Pflughaupt

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    I’m going to hazard an educated guess that your installer grounded the dish to the nearest water pipe, or whatever he could find. It needs to be grounded to the electrical ground stake at your breaker panel.

    Regards,
    Wayne A. Pflughaupt
     
  4. John S

    John S Producer

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    I find a high percentage of dish installs are plain wrong in some way on the grounding. I have actually seen several not grounded at all, inducing the same symptoms. So, my 1st advice is check their work extensively.
     
  5. Dave Miller

    Dave Miller Supporting Actor

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    How would I be able to tell if my dish is grounded? What should I look for?

    Peace,

    DM
     
  6. Kevin C Brown

    Kevin C Brown Producer

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    Turn on you audio system, and listen for a hum from your speakers. [​IMG] You might also hear a hum from the amplifier transformers themselves.
     
  7. Wayne A. Pflughaupt

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    Someone correct me if I’m wrong, but I think there’s supposed to be a heavy-gauge wire coming from the dish to the electrical ground stake. There should also be a ground wire in the coaxial line, using a gizmo like this:


    [​IMG]


    If you don’t see either one, or if the ground wires are going somewhere beside the main ground stake, then that’s what’s causing your problem.

    Regards,
    Wayne A. Pflughaupt
     
  8. Kevin C Brown

    Kevin C Brown Producer

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    Wayne- Any suggestions on finding that ground stake? I looked at my breaker box and I found the levers for the different circuits, but nothing stood out as being a connection for ground.

    One thing that might complicate things, is that the original breaker box outside looks to be unused. There was an addition to the house in '87, and they moved all the electrical stuff to a new box inside. (The original wiring was 1950 or so, and might not have even been grounded. All of the original oulets are only 2 prong. Luckily, the dude wired 20A circuits with a proper ground for the addition: the family room where my home theater is located [​IMG], and a larger kitchen.)
     
  9. John S

    John S Producer

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    You need to look at the dish itself and all leads comming off of it. Also look at where it comes into the house on the outside. Should be one of the doohickies posted on there. In the end, there should be ground leading to a main breaker box somewhere. If the one Breaker box is unused and that is where he grounded to, I'll cut the installer some slack as that is a uniqure situation, he may noth have caught.
     
  10. StephenL

    StephenL Second Unit

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    The dish mast and cable shield must be grounded to your house grounding electrode system. If a separate ground rod is used for the antenna, it must be bonded to the house grounding electrode system, becoming part of that system. This prevents a difference in ground potential between dish ground and power ground.

    National Electric Code approved grounding points
    http://www.dbsinstall.com/Whatis/Whatisgood-5.htm

    Antenna Grounding
    http://www.keohi.com/keohihdtv/hdrec...grounding.html

    http://www.mikeholt.com/technical.ph...lite%20Dish%20

    Preventing Damage Due to Ground Potential Difference
    http://www.cinergy.com/surge/ttip08.htm

    PSIHQ - Grounding Requirements
    http://www.psihq.com/iread/strpgrnd.htm

    Tower Page - see N1LO's GUYED TOWER TOPIC SUMMARY
    http://www.qsl.net/n1lo/tower.htm
     
  11. Dave Miller

    Dave Miller Supporting Actor

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    Wow, that first website is the best. Thanks so much. I will check.

    Currently, I have no humming issues, but my Dish, HDTivo & attic antenna were all installed in during the dry season back in November. Rainy season will be here soon and lightning is a real issue here in southwest Florida.

    Peace,

    DM
     
  12. Wayne A. Pflughaupt

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    Kevin,
    Are you sure it’s really grounded?

    It’s not hard to check out the new box. You can remove the cover to the breaker panel; it’s probably only 4 or so screws. With the cover removed you can see all the romex cables that come in. If you se the individuals cables break out into three wires – white, black and bare – and all the bare wires are tied to a buss bar, then the service should be grounded.

    There’s also a little plug-in gizmo you can get at the hardware store for a few bucks that will tell you in your service has a good ground.

    Regards,
    Wayne A. Pflughaupt
     
  13. Kevin C Brown

    Kevin C Brown Producer

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    Good suggestions. When we got the home inspection done when we bought, I remember the guy had one of those outlet testers. Did test OK in the addition. There is also a blanked off panel near the new breaker box too. Need to get my screwdriver out and see what I can see! Thanks.
     
  14. Kevin C Brown

    Kevin C Brown Producer

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    Wayne! [​IMG] I took off the breaker panel, and I see two "buss bar" type things. White wires go to one, bare copper to the other, and black wires go into each breaker switch. From replacing all my outlets already, the bare copper wires are the grounds, right? (Now, I wish I could figure out where that ground line goes to!)

    The Dish guy is here right now. I also found out where the cable guy did his ground: he grounded to the metal conduit going in to the old breaker box. That is *not* the same ground as what the house is grounded to now. Need to try and see what it would take to get the Dish guy to do it right, but that means probably having to go under the house, etc, ...

    >>> Added:

    OK, here's a strange one. With cable, I had a ground loop and had to put in one of those isolator things. I figured I'd let the Dish guy do his thing, and I'd worry about it later. Even though he hooked the Dish ground up to the same ground as the cable guy did, no ground loop with the Dish setup. I'm not complaining I guess! [​IMG]
     
  15. Wayne A. Pflughaupt

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    Hi Kevin,

    Mysterious for sure, but at least the noise is gone. [​IMG]

    About finding the ground for the new breaker box, there should be a heavy-gauge wire attached to the buss bar where all the bare (ground) wires are. That will be the wire going to the actual ground stake. If you can figure out where it goes, maybe you can find your ground stake.

    If not, grounding the cable and DSS services to the new breaker box will get the job done.

    Regards,
    Wayne A. Pflughaupt
     
  16. Kevin C Brown

    Kevin C Brown Producer

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    Wayne- There are three heavy duty cables that come in. Maybe 6 gauge or thicker. Really heavy. Looks like each one goes to white, black, and bare Cu. Everything disappears into the wall though so I can't tell where the ground goes from there.
     
  17. Wayne A. Pflughaupt

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    Hmm, that’s a little different from what I’m used to seeing here. Typically what you get here is three heavy-gauge cables, two blacks and one white. The two blacks are each 120 volts, and the white is the neutral. The ground cable isn’t part of the incoming service, but goes straight to the copper stake from the buss bar.

    But since this was a retro, it looks like they sent the ground to the panel from somewhere else. If you can’t find the ground stake outside the house anywhere (it may be where the phone or cable TV service comes in, or they may simply be using a water pipe for the ground), your best bet might be to get one of those little plug-in gizmos from the hardware store that will confirm if you have a good ground or not. If you can establish that you do, it will suffice to ground your sat dish or whatever directly to the breaker panel, or the ground buss bar if you’re brave enough to stick your hands in there. [​IMG]

    Regards,
    Wayne A. Pflughaupt
     
  18. Kevin C Brown

    Kevin C Brown Producer

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    Yeah, two blacks and a white, that's how you get 220V for a dryer, right?

    OK, I will continue to look. The new breaker box isn't that far from the dryer, so I should be able to trace what's going on...
     

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