I suffer from 'ground loop' ~

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pEtRa

pEtRa

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Hi all.

Yes, my 42" plasma suffer from this notorious problem, wherein I get this huge lines running from top to bottom of screen with a loud humming noise whenever I connect my STB to my TV. I had to find out what this problem is myself in google after many visits by panasonic service guys and cable guys and an electrician, they were just blaming each others components for this, got fed up.

I have a surge strip to which my amp, cdp and tv are connected.

I just don't know how to arrest this lines and hum noise. I found in net something called 'ground isolators' are available, where and how to fit it, i just don't know.

Please help, please.
 
i suppose you need a power conditioner. no idea where to get hold of it in your city though
 
6pack said:
do you get a tingling sensation when touching the stb cover (non plastic part)? if you do, i think your stb is not grounded properly.
Click to expand...

Yes I do, so how to ground them, pls help. I just read that a 'ground isolator' connected between the tv cable feed and the input of the STB will arrest hum noise and the annoying lines. Do they sell this in Richie Street in Chennai at all.

Pls help, i need to stop this hum and lines once and for all today itself.

I can't watch anymore those free channels from cable feed to my plasma tv.:(
 
^^ sorry for editing my post, it looked silly when i read it twice.

my updated post is more helpfull i think.
 
Please draw a picture of the way you're connecting everything to the electrical outlet, and to each other.

A simple drawing in Paint will do, and indicate which components have an earthing connection (3-pin plugs).

At a very basic level, removing the safety earth should help but is dangerous as everything will be live in case of a defect. This involves cutting off the earth pin of a 3-pin plug, or converting it to a 2-pin plug.

I would point the finger of suspicion at the STB first. A quick way to check this out is to connect the audio output of your CDP to the TV and power it off the same socket as the STB. If there's no disturbance, the grounds are fine. The audio and video ground in a TV set is usually the same point so it does not make a difference if you're using the video or audio input.

A diagram would really, really help.
 
I have same problem.

I get buzzing sound whenever connect my tata sky with onkyo and tv.

TV gets the lines which looks like old TV less voltage framin crap.

Onkyo gets humming sound...sometimes i slap tata sky and the sound goes..lol

I do need final solution, mate if you find any do let me knowww
 
sangram said:
Please draw a picture of the way you're connecting everything to the electrical outlet, and to each other.

A simple drawing in Paint will do, and indicate which components have an earthing connection (3-pin plugs).

At a very basic level, removing the safety earth should help but is dangerous as everything will be live in case of a defect. This involves cutting off the earth pin of a 3-pin plug, or converting it to a 2-pin plug.

I would point the finger of suspicion at the STB first. A quick way to check this out is to connect the audio output of your CDP to the TV and power it off the same socket as the STB. If there's no disturbance, the grounds are fine. The audio and video ground in a TV set is usually the same point so it does not make a difference if you're using the video or audio input.

A diagram would really, really help.
Click to expand...

Thank you for sharing. Here is the diagram you asked for.

MAP on Flickr - Photo Sharing!
 
1. Disconnect the cable input from the STB and check if the problem persists.

2. Use a spike strip without the 'noise filter'. This usually increases the line impedance and can actually make matters worse.

3. You've not yet indicated which of these have 3-pin plugs and which have 2-pin.

4. Did you try disconnecting the STB and using a ground check with the CDP? It may be a TV issue if that is the case, and (most likely) switching the ground out from the TV may sort out the issue.

5. When connecting the cable feed directly to the TV, do you get ANY interference or is it rock-stable?
 
sangram said:
1. Disconnect the cable input from the STB and check if the problem persists.

2. Use a spike strip without the 'noise filter'. This usually increases the line impedance and can actually make matters worse.

3. You've not yet indicated which of these have 3-pin plugs and which have 2-pin.

4. Did you try disconnecting the STB and using a ground check with the CDP? It may be a TV issue if that is the case, and (most likely) switching the ground out from the TV may sort out the issue.

5. When connecting the cable feed directly to the TV, do you get ANY interference or is it rock-stable?
Click to expand...

Hi:

1. Yeah did. Without cable feed and only the STB connected thru RCA to TV, no problem at all.

2. So, should I buy a new one?

3. Ok. TV has three pins. Amp has three pins. Cdp has three pins. DVD has two pins. STB has two pins. (hope thats what u mean)

4. I haven't tried it. But when connecting only DVD player to TV thru RCA cables, picture is stunning and no humming at all.

5. Yeah been watching till now that only, picture is too good to be true and sound is excellent.

Please help. I'm counting only you in the whole world mate to solve the issue.
 
I can't guarantee it'll work, but try this:

Get an extension cord, with a two-pin cable and at least one 3-pin socket. These are commonly available at your friendly neighborhood electrician, for under a hundred rupees.

Disconnect the spike strip from the wall outlet.

Plug in this extension cable into the wall.

Into the 3-pin socket, plug the TV. Into one of the 2-pin sockets, plug in the STB. Now connect the cable input to the STB, and the STB to the TV.

[WARNING] Because of the earth disconnect, any live voltage at the chassis will electrocute anybody who touches it. This is only a troubleshooting method, NOT a cure[/WARNING]

Ensure you switch off the mains when the system is not in use, and that no human being or animal is near the TV when it's operated like this. Also, I cannot guarantee your equipment will like this way of operating, and may refuse to operate or totally malfunction.

Report back, then we'll take it from there. So far:

1. Cable connection is fine, so there is no ground loop between the cable system ground and the TV, which is normally the cause.

2. STB is the only system not grounded to safety earth, so it is most probably the culprit here. I don't know what to recommend: Tata Sky or similar may not have these problems. You can force a safety earth to the STB chassis, but it's not recommended as there may be a high enough voltage on it to transfer live voltages to everything else.

This test will tell you if the defect is the STB or the electrical supply. If your problem is cured by this, the issue is the STB. If it is not, there's something wrong with your electrical system (such as reversed line/neutral or earth/neutral).

Once I tried, with no success, to troubleshoot a spike strip which was giving me a wonky reading - indicating that line/neutral was reversed. I struggled with it and went through three spike strips with the exact same issue. After four days it dawned on me that I had in fact connected the live and neutral the other way, as I was using the lower half of a multi-way mains splitter, which essentially inverts the plug orientation. So don't overlook anything.
 
sangram,

my tatasky have this problem.

it always sending humming, even onkyo engineer checked it. But still haven't found any solution, because this happens only sometimes.
 
sangram said:
I can't guarantee it'll work, but try this:

Get an extension cord, with a two-pin cable and at least one 3-pin socket. These are commonly available at your friendly neighborhood electrician, for under a hundred rupees.

Disconnect the spike strip from the wall outlet.

Plug in this extension cable into the wall.

Into the 3-pin socket, plug the TV. Into one of the 2-pin sockets, plug in the STB. Now connect the cable input to the STB, and the STB to the TV.

[WARNING] Because of the earth disconnect, any live voltage at the chassis will electrocute anybody who touches it. This is only a troubleshooting method, NOT a cure[/WARNING]

Ensure you switch off the mains when the system is not in use, and that no human being or animal is near the TV when it's operated like this. Also, I cannot guarantee your equipment will like this way of operating, and may refuse to operate or totally malfunction.

Report back, then we'll take it from there. So far:

1. Cable connection is fine, so there is no ground loop between the cable system ground and the TV, which is normally the cause.

2. STB is the only system not grounded to safety earth, so it is most probably the culprit here. I don't know what to recommend: Tata Sky or similar may not have these problems. You can force a safety earth to the STB chassis, but it's not recommended as there may be a high enough voltage on it to transfer live voltages to everything else.

This test will tell you if the defect is the STB or the electrical supply. If your problem is cured by this, the issue is the STB. If it is not, there's something wrong with your electrical system (such as reversed line/neutral or earth/neutral).

Once I tried, with no success, to troubleshoot a spike strip which was giving me a wonky reading - indicating that line/neutral was reversed. I struggled with it and went through three spike strips with the exact same issue. After four days it dawned on me that I had in fact connected the live and neutral the other way, as I was using the lower half of a multi-way mains splitter, which essentially inverts the plug orientation. So don't overlook anything.
Click to expand...

Hi:

I do have a spare extension box. So, what I did was, first, remove the surge protector plug from the mains. Then, I connected the two-pin plug of the extension cable to the mains. Now, in the two-pin socket of the extension box i plugged in the STB, and to the three-pin socket i connected the three-pin plug of plasma TV (till now i did not connect the cable TV feed to the STB). Now, I turned the power on, switched on the TV, no running lines and no humming. Then, I gingerly connected the cable TV feed to the STB, and they're back, running lines and humming noise.

Please am being fired from all quarters in house, i loved this TV very much, that's why I bought this for all household to enjoy, I cannot take this anymore. I know now that nobody can help except this forum. I cannot buy a new STB, please.

Please help me. Please.
 
Hmm.

First of all, relax. You can't fix everything in the world.

Try pulling the power from another outlet.

Go back to your original earthed spike, we've eliminated it as the source of the problem.

We still have to check with another STB, as well as for reversed line/neutral.

I do know that I had said that this would eliminate the STB, but it does not, as there may an issue with the SMPS bleeding into the chassis ground. Ask your cable guy to get another box (maybe another type of box, they usually have a few).

@raghav, thanks for that. Good (or not) to know that even a Satellite box has these issues.
 
even dish tv stb's have this issue of small current passing though the stb body. i think best way would be to ground the stb to a different earth rather than use it through an extension box together with the tv. tv and stb ideally should use different sockets and not share one socket imo.

(i'm guessing the reason for the excess power is the dish on top is not grounded by the installation people.)

@sangram, would grounding the cable wire from stb help to remove the problem? or maybe just taping a wire to a metal part of stb and attaching it to a three pin plug ground in different socket (Live and neutral no wires used) should remove the problem.
 
did u tried connecting the cable directly to the rf input of tv (without using stb).if u r still getting the problem then its because ur tv and cable have different grounds.. u need Cable TV RF Isolator..something like

JENSEN TRANSFORMERS, INC. - ISO-MAX® Audio Isolator Products

even i have same problem with local cable and my lcd tv..am thinkin about getting dth , hoping that then these devices share the common ground of my home,thus eliminating the ground loop problem
 
@6pack: It could help, I don't really know. It's not going to hurt to try, and if it solves the problem, nothing like it.

@Greenie: That might be the most sensible way out, if not the cheapest.

There is a last resort for ground lift, but it requires construction, you have to build a small device that will isolate the ground and live signal, using a 1:1 matching transformer in the cable line. Ask your cable guy to get you a ground lifter if he can, it's basically a 75:75 ohm isolator. They use these things all the time.
 
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