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· AllStar
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Discussion Starter · #1 ·
When I hook up my Olevia 747i to either my HR21, or my Stand alone Tivo via a component cable, I get moving horizontal red and green lines on my TV. I had the HR21 hooked up via HDMI and it looked fine, it's just component that results in the lines (see attached pic). I have a long component run from the HR21 in the living room into the bedroom where I just moved the 747i to. I previously had a 42" Philips in the bedroom. It (the Philips) did and still looks fine with the exact same component feed. I can literally unplug the feed from the Olevia (with lines) and plug into the Philips and not get the lines.
Here's the weird thing, if I unplug the 2 feeds from the dish to the HR21, the lines go away. There seems to be some kind of interference when the HR21 is hooked up to the dish. I have not tried unhooking the dish feed to the tivo to see if it removes the lines. I assume it would, but will check tonight.

This may not be the right forum, but it does involve an HR21 and since the problem seems to crop up ONLY when the dish is hooked up, I thought I'd run it by you guys.

Thanks for any thoughts.
John
 

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How about RFI...

How close are the coax cables to the component cables?

If "close", can they be moved apart?

And just out of curiosity, how long are those component cables?
 

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OK, just a thought...

So ground loop meaning that all devices do not have the same ground reference?

Or no ground at all?
 

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EricJRW said:
OK, just a thought...

So ground loop meaning that all devices do not have the same ground reference?

Or no ground at all?
"Somewhere" there is 60 cycles going to ground through the [analog] component cables.
This is quite common with cable TV, since their cables run for a long distance on the utility poles and it couples on to the cable feed.
A "simple" DC block, stops this.

As you move into DirecTV receivers, some don't have a three prong [grounding] plug, but if the SAT feed is grounded, then so is the receiver.
A resistive [bad] ground can cause this too, as the ground with the least resistance is where voltage "wants" to go.
 

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EricJRW said:
OK, just a thought...

So ground loop meaning that all devices do not have the same ground reference?

Or no ground at all?
Oh, this is a good one to get yourself involved in. Never heard of a "ground loop"? Neither did I until I read a couple of posts about them. And I've been an electrician for over 35 years. Got into arguments about grounding rods and how it was possible to have a different reference to ground in some instances.

I'm always willing to learn and always willing to admit I'm wrong, but all those arguments I had didn't change my mind about ground references. I had people from Michigan and Wisconsin telling me I had an eight foot grounding rod that my service was connected to. Insisted that I did not and that the grounding for my house is supplied by a block on my water pipe entry to the home. And a plumber and I found the original grounding block a couple of weeks ago while installing a new deep sink.

I finally had a D* tech put a "grounding block" on my cabling. I've installed ground blocks, bugs and lugs to copper rods and couldn't believe what D* terms a "grounding block". Which had to be wired to a real grounding block. What they do is a lot cheaper than doing the proper thing and running a ground wire to the ground block.

Some of the members are more electronically oriented than I am and they truly believe in "ground loops" and can offer up a pretty good argument for their existence. I see VOS is on this thread and will probably give you a good interpretation of "ground loops". And I guess in the world of electronics they might well exist. In the electrical world, ground is ground. What kind of different "reference" could you possibly see in ground?

Remember, there is no "Science of Electricity". There is only the Theory of Electricity and electronic devices are still electric devices first. In other words, anything is possible. I'm just not sure that "ground loops" is the correct nomenclature.

Rich
 

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My experience with different ground reference (different potentials) was this...

I was installing paging equipment (part of my "customer support" role when I was a software guy). I forget the exact problem, but basically one piece of equipment would only work if the serial port console was plugged in. Unplug the console, it would not work. Plug it in, all was well. Well one time I just happened to be plugging/unplugging, and as I held the cable in one hand and leaned against the rails in the cabinet, I got a mild electric shock... I was like, "Wow, never noticed that before." To make a long story short (no pun intended) something was not grounded and it was using the ground on the serial cable, which was connected to a device that WAS grounded, to complete the circuit. Not sure what side was fixed (isolate the other ground, or properly ground the "odd" device), but that shocking little discovery solved a BIG mystery...

Rich, have you ever installed any isolated ground duplex receptacle (like the P&S IG6300)? If you have, I'm trying to figure out the metal strap along the back... Can't find a picture, but I'll have one tomorrow. No big deal, just the construction has me curious.

Eric
 

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Discussion Starter · #10 ·
EricJRW said:
How about RFI...

How close are the coax cables to the component cables?

If "close", can they be moved apart?

And just out of curiosity, how long are those component cables?
The coax cables run up the living room wall and down the bedroom wall with the component cables...the run acroos the attic they are not next to each other. The component cable that runs thru the attic is 75 feet. The "test" cable is 50'. I know that is long, but both cables deliver a good signal to the Philips TV all the time, and to the Olevia TV when the satellite is not connected.

I am open to any alternatives to getting an HD signal to the bedroom. Can HDMI push 60 feet or so? My other choice is some sort of CAT6 and all the hardware associated with it. I'd rather not spend the $$, but would if I had to. I'd rather resolve the issue, though.

Is the consensus a ground loop issue? If so, what is the best way to resolve it. I am fairly handy, but ignorant on the specifics of how to properly ground a dish.
John
 

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veryoldschool said:
"Somewhere" there is 60 cycles going to ground through the [analog] component cables.
This is quite common with cable TV, since their cables run for a long distance on the utility poles and it couples on to the cable feed.
People reading this will find it hard to believe, but I used to work in an old chemical plant and we had armored cables buried underground that were as long as a mile. These were large cables with many separate conductors in them (lotsa wires). With both ends separated from any power source, we could always find voltages up to 120 volts and it was always AC. I asked an old electrician who I had a great deal of respect for why this happened. He said something like, "I don't know for sure, but it's like the wire wants to "be hot". We showed several electrical engineers and they couldn't come up with a truly rational reason. I still don't have any idea why it was AC voltage. No power behind it, no danger of shock, but I put a Wiggy across two conductors and felt the coil in the Wiggy vibrate. Didn't last long, seemed to drain the voltage quickly, but it was there.

As you move into DirecTV receivers, some don't have a three prong [grounding] plug, but if the SAT feed is grounded, then so is the receiver.
So, for the last six years my system was not grounded. Not one installer knew how to do it. I kept asking where the ground was and never got an answer. And all they had to do was put their "grounding block" on the cable and attach it to the ground block on my outside water faucet. Took the guy that finally did it ten minutes.

A resistive [bad] ground can cause this too, as the ground with the least resistance is where voltage "wants" to go.
I've had this happen many times and each time it was because the electrician didn't tighten the lug properly.

The way to check your grounds easily, assuming you have GFIs installed, is to put a Wiggy lead on the screw of a receptacle cover an the other lead into the smaller of the two openings on the receptacle. Should trip the GFI immediately.

That's it? Where were you when I went thru this last year with those guys from Michigan and Wisconsin? Seems like they've been chasing "ground loops" for years.

They had me going "loopy".

Rich
 

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rich584 said:
Some of the members are more electronically oriented than I am and they truly believe in "ground loops" and can offer up a pretty good argument for their existence. I see VOS is on this thread and will probably give you a good interpretation of "ground loops". And I guess in the world of electronics they might well exist. In the electrical world, ground is ground. What kind of different "reference" could you possibly see in ground?

Remember, there is no "Science of Electricity". There is only the Theory of Electricity and electronic devices are still electric devices first. In other words, anything is possible. I'm just not sure that "ground loops" is the correct nomenclature.

Rich
At the voltages you've been using, I'd say "ground is ground". It is either grounded or not.
At much smaller voltages, the resistive component of the "ground" means not all grounds are equal.
Using an oscilloscope set to millivolts, will give you a whole new view of "ground". In some test setups, "where" a box is plugged into the same power strip can affect the grounding. At this level simply the resistance "of the ground" can vary your measurements and you've already dropped yourself off "building ground" as it's way too noisy.
"I think" the term "loop" comes from one piece of equipment "looping through" another as it goes to ground, be it a shield of a cable, ground of a serial cable, etc.
 

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EricJRW said:
Rich, have you ever installed any isolated ground duplex receptacle (like the P&S IG6300)? If you have, I'm trying to figure out the metal strap along the back... Can't find a picture, but I'll have one tomorrow. No big deal, just the construction has me curious.

Eric
Haven't got a clue what that is. I shall Google it.

Rich
 

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If I'm understanding what VOS is saying (correct me if I'm wrong, I'm very interested in this), you need to make sure that:

a) Your dish is properly grounded*, and
b) [assuming TV is three prong] that the outlet it is using is also grounded (on the same ground). Something like this might help:
http://www.extech.com/instrument/products/alpha/ET15.html

Assuming it is grounded, one way would be to check for a difference (using a volt meter) between the two grounds.

By all means, what till VOS and Rich weigh in, I'm no electrician, but as an "IT guy", I have to trouble shoot this stuff way more than I would like.

* Is your dish properly installed and grounded?
Satellite Dish FAQ
 

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I have the exact same problem with my H20 in the bedroom. Component putting the red and green lines in. HDMI, no problem. Component cable is only 1 meter. This problem did not show up for over 6 months after the installation was made and is intermittent. It is not a constant. Took me quite a bit of troubleshooting to find the culprit, the component in. I was searching for ground loops, different potential grounds, cable run, etc. None of that was the problem. All of my components, H20, DVD, and Sony 40" LCD are plugged into a UPS and the AV is plugged into the same circuit as the UPS. I could not figure out what was the problem, especially since it was not a constant. My fix was HDMI from the H20 and component from the DVD. Solved the problem. The DVD has never exhibited the lines on the TV. So, for the gurus out there, figure this one out. I haven't a clue as to the cause, and if it was ground potential or loop, the DVD player should exhibit the same symptoms, should it not? All are hooked to the same components and circuit. I also have an HR20 downstairs. Will try unhooking at the ground block outside and hook the component back up upstairs and see if the lines show up. If not, it has something to do with the HR20 and H20 onnected to the common dish.
 

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rich584 said:
Haven't got a clue what that is. I shall Google it.

Rich
You guys weighed in before I was done typing... :)

Anyway, here's what the receptacle looks like:

http://www.lowes.com/lowes/lkn?action=howTo&p=Improve/IsolatGnd.html

But it's the back that has me curious... I'll have the photo tomorrow (still can't find one on-line), and unless you guys don't mind the hijack, I'll PM you.

Oh, and our on-site electrician "never really noticed the back" either, which only furthered my curiosity.

PS. Maybe I'll pull the panel cover too and see where those IG ground wires are going...

PPS. I also noticed that the ground lug the installer installed was not very tight, so I snugged it up (along with the F-type connectors) seen here. You can also see that one boot (?) is not so straight, which is what made me check the whole thing. I'm probably going to fix that drip loop too!
 

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rich584 said:
People reading this will find it hard to believe, but I used to work in an old chemical plant and we had armored cables buried underground that were as long as a mile. These were large cables with many separate conductors in them (lotsa wires). With both ends separated from any power source, we could always find voltages up to 120 volts and it was always AC. I asked an old electrician who I had a great deal of respect for why this happened. He said something like, "I don't know for sure, but it's like the wire wants to "be hot". We showed several electrical engineers and they couldn't come up with a truly rational reason. I still don't have any idea why it was AC voltage. No power behind it, no danger of shock, but I put a Wiggy across two conductors and felt the coil in the Wiggy vibrate. Didn't last long, seemed to drain the voltage quickly, but it was there.
You might need to come up with a picture of "Mr. Wiggy" [if you don't get banned for doing it] :lol:

"I'd bet" you know a thing or two about transformers, which use mutual inductance. Now picture the winding all layed out. You have a field around one wire and another wire near it [long runs of course]. Now you have the fields cycling at 60 Hz. Your "secondary winding" is going to have voltage induced in it, but little to no amps [poor transfomer].
Where were you when I went thru this last year with those guys from Michigan and Wisconsin? Seems like they've been chasing "ground loops" for years.

They had me going "loopy".

Rich
"Banned" from discussing grounds as nobody would [wanted to] listen.

"Then there was the one" where a contractor tried to have me measure my "hot leg" and neutral leg, with a volt meter and I shouldn't have more than a two volt reading. I found it just a bit hard to believe if the circuit was "live" that I wouldn't have closer to 120 volts, but "I could get it through to him".
 

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EricJRW said:
If I'm understanding what VOS is saying (correct me if I'm wrong, I'm very interested in this), you need to make sure that:

a) Your dish is properly grounded*, and
b) [assuming TV is three prong] that the outlet it is using is also grounded (on the same ground). Something like this might help:
http://www.extech.com/instrument/products/alpha/ET15.html

Assuming it is grounded, one way would be to check for a difference (using a volt meter) between the two grounds.

By all means, what till VOS and Rich weigh in, I'm no electrician, but as an "IT guy", I have to trouble shoot this stuff way more than I would like.

* Is your dish properly installed and grounded?
Satellite Dish FAQ
It seems like you have a good grasp of it.
 

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veryoldschool said:
At the voltages you've been using, I'd say "ground is ground". It is either grounded or not.
At much smaller voltages, the resistive component of the "ground" means not all grounds are equal.
Using an oscilloscope set to millivolts, will give you a whole new view of "ground". In some test setups, "where" a box is plugged into the same power strip can affect the grounding. At this level simply the resistance "of the ground" can vary your measurements and you've already dropped yourself off "building ground" as it's way too noisy.
"I think" the term "loop" comes from one piece of equipment "looping through" another as it goes to ground, be it a shield of a cable, ground of a serial cable, etc.
That's what I hated about electronics. Little bitty voltages, minuscule amps and tiny resistors. Millivolts. My God. In ten years electronics will be on a quantum level. That would solve the fuel problem. We'd be able to use solar panels for electronic appliances.

Fred says "Hi".

This actually makes sense:

From Wackypedia:

A ground loop in a medium connecting circuits designed to be at the same potential but actually at different potentials can be hazardous, or cause problems with the electrical system, because the electrical potential at different points on the surface of the Earth can vary. Such an occurrence can be hazardous, for example, to personnel working on long metal conductors.

In a floating ground system, that is, one not connected to Earth, the voltages will probably be unstable, and if some of the conductors that constitute the return circuit to the source have a relatively high resistance, or have high currents through them that produce a significant voltage (I·R) drop, they can be hazardous.

Low current wiring is particularly susceptible to ground loops. If two pieces of audio equipment are plugged into different power outlets, there will often be a difference in their respective ground potentials. If a signal is passed from one to the other via an audio connection with the ground wire intact, this potential difference causes a spurious current through the cables, e.g.: creating an audible buzz at the AC mains base frequency (50 or 60 Hz) and the harmonics thereof (120 Hz, 240 Hz, and so on), called mains hum. Sometimes, performers remove the grounding pin from the cord connecting an appliance to the power outlet, however, this creates an electrocution risk. The first solution is to ensure that all metal chassis are interconnected, then to the electrical distribution system at one point (often referred to as a "single-point ground"). The next is to have shielded cables for the low currents, with the shield connected only at the source end. Another solution is to use isolation transformers, opto-isolators or baluns to avoid a direct electrical connection between the different grounds. However, bandwidth of such is of consideration. The better isolation transformers have grounded shields between the two sets of windings. In circuits having high frequencies, such as computer monitors, chokes are placed at the end of the cables just before the termination to the next appliance, e.g. the computer. These chokes are most often called ferrite core devices.

In video, ground loops can be seen as hum bars (bands of slightly different brightness) scrolling vertically up the screen. These are frequently seen with Video projectors where the display device has its case grounded via a 3-prong plug, and the other components have a floating ground connected to the CATV coax. In this case the video cable is grounded at the projector end to the home electrical system, and at the other end to the cable TV's ground, inducing a current through the cable which distorts the picture. As with audio ground loops, this problem can be solved by placing an isolation transformer on the cable-tv coax. Alternatively, one can use a surge protector that includes coax protection. If the cable is routed through the same surge protector as the three-prong device, both will be regrounded to the surge protector.

Ground loop issues with television coaxial cable can also affect any connected audio devices such as a receiver. Even if all of the audio and video equipment in for example a home theater system is plugged into the same power outlet, and thus all share the same ground, the coaxial cable entering the TV is actually grounded at the cable company. The potential of this ground is likely to differ slightly from the potential of the house's ground, so a ground loop occurs, causing undesirable mains hum in the system's speakers. A cheap way to resolve this problem is to buy a 75-Ohm Coax Combiner-Splitter and a "Matching Transformer". The 75-Ohm Coax Combiner/Splitter converts the impedance from 75 ohms to 300 ohms and the "Matching Transformer" converts the impedance from 300 ohms to 75 ohms. Both parts connected together will act as a "poor man's" isolation transformer.

Ground and ground loops are also important in designing circuits. In many circuits, large currents may exist through the ground plane, leading to voltage differences of the ground reference in different parts of the circuit, leading to hum and other problems. Several techniques should be used to avoid ground loops, and otherwise, guarantee good grounding:

Rich
 

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HD AV said:
I have the exact same problem with my H20 in the bedroom. Component putting the red and green lines in. HDMI, no problem. Component cable is only 1 meter. This problem did not show up for over 6 months after the installation was made and is intermittent. It is not a constant. Took me quite a bit of troubleshooting to find the culprit, the component in. I was searching for ground loops, different potential grounds, cable run, etc. None of that was the problem. All of my components, H20, DVD, and Sony 40" LCD are plugged into a UPS and the AV is plugged into the same circuit as the UPS. I could not figure out what was the problem, especially since it was not a constant. My fix was HDMI from the H20 and component from the DVD. Solved the problem. The DVD has never exhibited the lines on the TV. So, for the gurus out there, figure this one out. I haven't a clue as to the cause, and if it was ground potential or loop, the DVD player should exhibit the same symptoms, should it not? All are hooked to the same components and circuit. I also have an HR20 downstairs. Will try unhooking at the ground block outside and hook the component back up upstairs and see if the lines show up. If not, it has something to do with the HR20 and H20 onnected to the common dish.
As Rich has posted: grounds can make/drive you loopy.
Once you go digital, the [small] 60 cycles is still there but below the "ones & zeros" threshold so it doesn't care [ignores it].
To get into your "why" would take much more info about your system, setup, etc.
 
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