Ground Loop from Dish 622

[greenemister]

I have been chasing one down for a while, finally narrowed it to the 622 HDMI output to my Yamaha A/V unit. When I disconnect the HDMI to the A/V, it goes away. I then ran a ground wire from the dish to earth, and from the DPP to earth, no bueno. Should I try to ground the 622? Isn't the 622 already grounded via the power cable?

Thanks in advance.

John

Equipment:

VIP 622
921
Series 500 DVR
DPP 44
Yamaha HTR-5990
Axiom 7.1 w/powered S/W (that is where the hum is prominent)
Pany Plasma (love that baby)
ZeroSurge Supressor

 

[Jim5506]

You must use the same common ground point for all electronics and power in the house, otherwise you may very well establish a ground loop.

 

[RockinHARD26]

Any updates on this situation? I upgraded my sound system and I have a hum that is driving me crazy.

 

[Jim5506]

It has to hum, it doesn't know the words. . . . SORRY!

 

[highdefjeff]

Jim 5506 answered your question. If you don't bond somewhere in the houses' ground system, you can create the loop...taking them to the earth is not correct.

 

[KKlare]

Buy a sub-$5 3-neon circuit tester, see any hardware store. Six years ago I found my house of then 24 years had exactly 1/2 of all circuits with neutral (white) and hot (black) reversed. So with some 2-wire applicances/electronics supplying a high-Z trickle to neutral there was a spark when connecting them to coax etc. That would give you a hum and a shock. Hope you do not have to rewire too many.
-Ken

 

[steve4810]

I have a 622 hum also and I know my electrics are OK. I've lived here since the house was built and I have done all the subsequent additions and mods to them my self.

In my case the hum is severe enough to cause a very very faint, but see-able noise bar crawl up the screen of the TV1 DVI flat panel (something I didn't think was possible... digital and all) and TV2 component video on a 27" tube job in another room.

For 30 yrs and piles and piles of electronic stuff I've not had a hum problem since my homebuilt Heathkit Stereo receiver during our first year here. (jeezz I'm old!)

I hadn't decided that it was the 622 as there is also a new HD cable box on the same desk and lots of new cable runs and switches and such but since John brings it up is it possible this could be an issue.

Just now as a test I pulled the power plug on the 622 and the hum stopped on both TVs.

 

[highdefjeff]

What no one will tell you...

steve 4810 you wrote "In my case the hum is severe enough to cause a very very faint, but see-able noise bar crawl up the screen of the TV1 DVI flat panel (something I didn't think was possible... digital and all)"

Most will disagree with what your eyes are telling you, but you've discovered the truth about digital picture.

Digital picture does vary in quality for a variety of reasons. For more on noise and digital picture quality see:

Signal and HD Quality - What no one will tell you!

 

[steve4810]

Thanks Jeff.

I found two mistakes in my post. (1.) I have TV1 connected via Component cables and (2.) TV2 by composite cable.

I understand these are both analog signals. Is that right? If so, then an HDMI would cure TV1 but TV2 and the hum would remain. Right?

 

[RockinHARD26]

My house is brand new, cost me a couple million actually. The wiring is the way it should be throughout the entire place. Would this item work for the hum:

http://www.amazon.com/dp/B00023XDYA...e=380337&creativeASIN=B00023XDYA&linkCode=asn

 

[steve4810]

My house is brand new, cost me a couple million actually. The wiring is the way it should be throughout the entire place. Would this item work for the hum:

http://www.amazon.com/dp/B00023XDYA...e=380337&creativeASIN=B00023XDYA&linkCode=asn

My point is that I had no hum before the 622. Now I do. I don't think I should need to buy a gadget to cure a problem Dish equipment caused.

Remember though it hasn't been proven yet it is the 622. It seems very unlikely. Yet at least two of us 622 owners have hum where none was before.

 

[8bitbytes]

If the ground is correct in your home, then a bad 622 would not introduce a ground loop. A proper ground eliminates that from happening to other equipment. If you had ahum from the audio out of the 622 and nothing else, you might have a case but since other items not connected to the 622 hum, then the 622 has just helped you discover that something is not right.

 

[RockinHARD26]

I just said heck with it. When 622 is connected to my big screen TV and the volumn is not turned too high, you can not hear the hum. I even had the sound system hooked up to the optical digital light port thing in the back and I still had the hum plus it was delayed a second or two. So none of the sounds matched up the screen. It made me feel as if I was watching an international film in another language. I just have the sound system hooked up to my 222 in the bedroom. No hum there. I'm going to leave this area up to the professionals cause it got me really annoyed.

 

[steve4810]

If the ground is correct in your home, then a bad 622 would not introduce a ground loop. A proper ground eliminates that from happening to other equipment. If you had ahum from the audio out of the 622 and nothing else, you might have a case but since other items not connected to the 622 hum, then the 622 has just helped you discover that something is not right.

In my case the hum is on the 622 audio only and the noise bar is only visible when the input is from the 622. OTA(not connected to the 622), cable and DVDs have no hum or noise bars. It's definitely from the 622 or is getting amplified by the 622's audio amp. But if the later is true why doesn't the cable box or DVD player amplify the hum? They are all on the same circuit.

However since I still have a rat's nest of wires on the desk I have hope that when I get time to get everything properly stowed and the wires neatly routed the hum will be gone although I've had a lot of wire rat's nests before and never had a hint of hum.

 

[8bitbytes]

Ok, one other angle - your incoming cables from the dish are not properly grounded. Check and see if the line from the dish itself is connected to a ground block anywhere and the ground block is then connected to the house ground.

 

[highdefjeff]

Thanks Jeff.

I found two mistakes in my post. (1.) I have TV1 connected via Component cables and (2.) TV2 by composite cable.

I understand these are both analog signals. Is that right? If so, then an HDMI would cure TV1 but TV2 and the hum would remain. Right?

Yes, they are both analog signals but, no, the HDMI wouldn't do it. The interference is happening before you get to those cables. Here's what a ground loop is, and how a ground loop occurs.

When a satellite system is installed without a ground, or is improperly grounded, a ground loop occurs. Period. The ground loop is caused when there is more than one ground connection path between two pieces of equipment. For example, if the dish is grounded to a copper ground rod driven into the ground, and the receiver is grounded to the houses ground through the three prong grounded outlet, a ground loop is created because of the different potential between the two grounds.

The duplicate ground paths that occur form the equivalent of a powered loop antenna which very effectively picks up interference currents. (Satellite systems power up the coaxial cables all the way back to the LNB as they back-feed voltage to the LNB to activate it for the correct transponder needed.) These currents are transformed into voltage fluctuations.

The resulting ground loop induced voltages cause the ground reference in the system to have an unstable potential, so the signals ride on the noise. The noise then becomes part of the program signal.

What is happening occurs between the receiver and the dish and all related cabling. By the time you get to the output, the noise is already merged with the output signal.

HDMI would likely produce a similar result as component or composite cable.

 

[highdefjeff]

My house is brand new, cost me a couple million actually. The wiring is the way it should be throughout the entire place. Would this item work for the hum:

http://www.amazon.com/dp/B00023XDYA...e=380337&creativeASIN=B00023XDYA&linkCode=asn

Maybe.
But the underlying cause will not be fixed.

Ground loop induced noise resulting in hum is only one symptom of a potentially greater problem. That product is like the pain killer helping the pain, but not fixing your broken arm from where the pain is originating. The ground loop interference is only one little symptom of improper grounding.

Improper grounding can result in electronic component failure, or in extreme cases, a large electrical current flowing through the cabinet of your satellite receiver. Lack of or improper grounding also DRAWS lightning to your system and doesn't allow for the draining of stray signals or static electricity from the reflector. Proper grounding also provides some protection during power surges.

While many people will not notice the effects of their ungrounded system, grounding is not just the law, it very certainly has it's place in the proper functioning of the satellite system.

 

[RockinHARD26]

Maybe.
But the underlying cause will not be fixed.

Ground loop induced noise resulting in hum is only one symptom of a potentially greater problem. That product is like the pain killer helping the pain, but not fixing your broken arm from where the pain is originating. The ground loop interference is only one little symptom of improper grounding.

Improper grounding can result in electronic component failure, or in extreme cases, a large electrical current flowing through the cabinet of your satellite receiver. Lack of or improper grounding also DRAWS lightning to your system and doesn't allow for the draining of stray signals or static electricity from the reflector. Proper grounding also provides some protection during power surges.

While many people will not notice the effects of their ungrounded system, grounding is not just the law, it very certainly has it's place in the proper functioning of the satellite system.

Its funny you say that, I'm currently on pain killers and the cause is not being fixed.

 

[charlesrshell]

How do you test basement water pipes to make sure they are grounded to the home's grounding rod? I have a muti-meter, what do I do? Thanks

 

[highdefjeff]

First answer is this...

If your copper pipe remains copper the ground, (doesn't have any PVC in the line between where it comes in the house and is contacted) then it is a proper placement and grounded correctly.

Technically, within 5 foot of entry into the building is where the pipe clamp or strap should be placed.