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Guest Message by DevFuse


Odd interaction between phone, lights, and HR21-100


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4 replies to this topic

#1 OFFLINE   fleckrj



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Posted 09 February 2012 - 12:04 PM

Here is a strange situation. When the telephone line is connected to my HR21-100 AND the LED pot lights in the TV room are on, there is a hum (60 Hz) on the telephone line. If I disconnect phone line from the HR21-100, there is no hum, regardless of whether the lights are on. If I turn off the lights, there is no hum regardless of whether the HR21 is connected to the phone line. The hum is only present when the HR21 is connected to the phone line and the lights are on.

I thought that the phone line itself might be acting as an antenna to pick up RF interference from the lights, but if I leave the line connected at the wall and disconnect it from the HR21, the hum goes away. I have tried using phone cables of different lengths in an attempt to find a length that is not a harmonic of the interference, but that had no effect on the hum. I have tried routing the phone line through a surge protector and without the surge protector with no change.

If it was a grounding problem with the HR21, I would expect the hum to be independent of whether the lights were on. The lights and the HR21 are on different electrical circuits, but both are from the same service panel and both are grounded properly.

The only thing I have not yet tried is using a shielded phone cable that is designed for use with ADSL modems, but since the hum is not present when the existing cable is attached to the wall but not to the HR21, I doubt this will solve the problem.

Does anyone have any ideas?

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#2 OFFLINE   caseyf5



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Posted 09 February 2012 - 03:35 PM

Hello fleckrj,

One thing comes to mind. Have you installed the telephone line filter for the ADSL modem? If it is installed try to substitute another one. Removing the filter works some of the time also. If these suggestions do not work then try another receiver/dvr in the tv room if you have one and put the HR21-100 where the other unit was located. Best of luck in resolving your problem. If it persists then I am sure that other people are willing to assist you.


#3 OFFLINE   azarby


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Posted 09 February 2012 - 04:38 PM

The problem actualy stems from the light controller. They use a switching circuit that pulsates the power to the light bulb. Because of the way they designed the circuit ( low cost mass produced) , these pulses are being induced back into the power and neutral. A good power line filter may take care of the problem, otherwise a different controler is required. The reason that you see the problem with the phone and DTV is that they did a poor job of isolating the power line form the phone circuitry. Probably again to keep costs down. If you are connected to the internet, I would just not use the phone line. You won't have CID, but in my experience, DTVs CID is hit or miss anyhow.

#4 OFFLINE   fleckrj



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Posted 10 February 2012 - 07:28 AM

Thanks for the replies. I already have the HR21, TV, AVR, and blu-ray player plugged into a Panamax Power Conditioner/Surge Protector. I did have the phone line running through that, too. In an attempt to eliminate the hum, I ran the phone line directly from the wall to the HR21 with no change in the hum.

I do have a DSL filter on the phone line. I do not remember if I checked for the hum without the filter, but I can try that. I also have two more DSL filters that have never been used. I can try one of those.

I do not use CID, so the only reason the phone line is connected to the HR21 is to order PPV. The HR21 is not connected to the internet, but I do have a 802.11(n) router. Line of sight from the router to the HR21 is only about 18 feet with no walls in the way, but it would be extremely difficult to run an ethernet cable from the router to the HR21. I know that USB wireless transmitters do not work on the HR21.

What is the best way to connect the HR21 to the internet wirelessly?

#5 OFFLINE   veryoldschool


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Posted 10 February 2012 - 09:32 AM

What is the best way to connect the HR21 to the internet wirelessly?

DirecTV offers a wireless CCK:


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