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-   -   Ground Loop Issue (https://www.digitalhome.ca/forum/66-cogeco/272657-ground-loop-issue.html)

taylormade 2017-04-04 02:22 PM

Ground Loop Issue
 
Hi,

Cogeco just hooked up my Tivo and as soon as they connected the receiver I get a loud buzz (ground loop) from my 60,000.00 system. This is the first time I have had Cogeco TV and have not had ground loop problems with any other equipment. They tried two boxes and both create the hum, any idea if it is my responsibility to fix it or Cogeco's? I would like to get Cogeco as it is my only way to get 4k and nobody I have talked to at Cogeco (6 people now) even know what a ground loop is.

JamesK 2017-04-04 03:07 PM

First off, make sure all the equipment is connected to the same AC outlet. Also, the cable *MUST* be connected to the house ground at the same point as the power.

ExDilbert 2017-04-04 03:24 PM

The first thing to check is that the Cogeco RG6 cable is properly grounded where it enters the house. If the ground loop is caused by the incoming cable (the most likely cause in this case) it may fix the problem. That is accomplished by running a minimum #10 wire from a grounding block on the cable to the household common ground used by the house panel (not the panel itself.) That is Cogeco's responsibility. Failure to do so is against the Canadian Electrical Code and could cause injury and property damage.

Beyond that, it is your responsibility to track down ground loops inside the house. The best way to remedy is with equipment isolation. That may be done by inserting a 75 ohm isolating transformer on the incoming cable, after the grounding block. That may affect the cable signal if it is not a good quality device. Cogeco may be able to supply one.

The loud hum is caused by the 60Hz ground loop signal entering cables or equipment. Poor quality analog audio cables are easily replaced with heavy gauge cables but better quality equipment can be expensive. One remedy is to use fibre optical cables where possible. That can be done with many audio devices. Unfortunately, the common use of HDMI for video and audio does not allow that with other devices. Bonding equipment to a common ground is another solution. That can be done by using a common power bar or common panel circuit for all devices. Another way is by using a heavy gauge cable or connecting a grounding conductor between the problematic devices. In some cases, ground loops can be caused by faulty household wiring. That should be tracked down and corrected by a qualified person.

taylormade 2017-04-04 03:47 PM

Thanks for the replies, they tied the cable ground wire to the pipe going down from my main power meter, maybe I need to sand it to get a better connection or get them to run the ground into the house and use the one by the main panel?, too bad I can't show a picture on here, as for all equipment being on the same outlet, I have 6 separate dedicated outlets and two power conditioners full of devices plugged into them, plus my 4 amps that use dedicated lines. If all else fails is a ground loop isolator a possible solution?

ExDilbert 2017-04-04 04:03 PM

I used one on the incoming TV cable some 15 years ago to resolve a ground loop issue. Don't know if they are still available but they do work.

JamesK 2017-04-04 04:06 PM

Quote:

they tied the cable ground wire to the pipe going down from my main power meter
I have seen another company tie the ground wire to the meter conduit, right over paint, so there was no good connection. It should be connected to the same ground point as the power, phone line, etc.. There is supposed to be only a single common ground point used.

taylormade 2017-04-04 04:24 PM

Ah ha, looks like there is paint on the pipe, I'll scrap that off and see what happens, thanks again guys, appreciate the quick responses.

JamesK 2017-04-04 04:59 PM

^^^^
There are a lot of "techs" who really don't understand the principles of what they're doing. On a project I was working on recently, where shielded Ethernet cable was used, another guy didn't know that the shield has to be grounded to be effective. Over the years, I have seen a lot of that sort of lack of knowledge.

57 2017-04-04 06:49 PM

Quote:

Originally Posted by taylormade (Post 2903465)
...too bad I can't show a picture on here...

Actually you can, see the bottom of the first post in the link below:

http://www.digitalhome.ca/forum/52-d...tal-forum.html

There are plenty of previous ground loop discussions and as mentioned in previous posts, it's usually a poor grounding on the incoming cable.

taylormade 2017-04-04 08:57 PM

Thanks I'll figure that out later, nothing I did changed anything, actually disconnecting the ground altogether did nothing. Thinking when the guy made his own end connectors, maybe he screwed something up then I will start with all of ExDilbert's suggestions, but it has to be the cable coming in as it only started happening when I got cable tv and no other devices produce the hum.

Something interesting, the receiver still creates the buzz when not plugged in.

taylormade 2017-04-04 10:56 PM

I have fixed my issue, I had coax input and outputs on the back of one of my power conditioners, ran the cables through it and all is good now. Whew, thanks again all.

denben73 2017-04-04 11:04 PM

:smile

Good to hear! Enjoy!

taylormade 2017-04-04 11:25 PM

You sure get around :)

denben73 2017-04-04 11:25 PM

:grin

Back at ya.

57 2017-04-04 11:58 PM

Quote:

Originally Posted by taylormade (Post 2903713)
I have fixed my issue, I had coax input and outputs on the back of one of my power conditioners, ran the cables through it and all is good now. Whew, thanks again all.

I always consider that a bandaid solution and you should really find the source of the problem instead of putting on a bandaid. Especially with your equipment - it's like putting on headphones, or turning up the radio, so you don't hear a potentially expensive/damaging noise in a vehicle.

Some of these items (conditioners, UPS, etc) can interfere with the cable signal - especially the return signal required for Cogeco monitoring, for On-demand, SDV channels if applicable, firmware downloads, etc.

Most service providers and most audio/video-philes will advise you not to go "through" such a device with RF-coax.


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