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Ask Anthony F. Your Own Question
Anthony F.
Anthony F., Owner of TV Service Center
Category: TV
Satisfied Customers: 9830
Experience:  20+ yrs. of experience in TV repair, TV production and engineering as owner of TV service center.
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i have a humming noise when i hook up my digital cable box

This answer was rated:

i have a humming noise when i hook up my digital cable box to my LCD tv through rca composite cables.

Anthony's TV :

Hello JA Customer I have been fixing Tv and Electronics since I was 5 years old With better than 20 years experience and 17 years in business

Anthony's TV :

the most likely cause is you have confused the RED audio wire with the RED Component wire

Anthony's TV :

and you are feeding video into your audio jacks

Customer:

i'm not running component cables. just the red/white/yellow composite cables. little background on what i'm doing. i mounted a tv on the wall above my fireplace. on both sides of the fireplace, there are book shelves from floor to ceiling. i took all the wood off the wall above the fireplace to be able to run my wires inside the wall to one side of the fireplace where i have the digital box and dvd player. so the cables i have ran are 2 hdmi cables, one component cable, one composite cable, and one coaxail cable. to hook up my digital box from my cable company, my initial problem was that when i ran the coaxail from the outside to the digital box, then output the signal via coaxial to the tv, the tv said there was no signal and didn't work. i would think it should... should it not?? to get around this i just plugged in the composite(red,white,yellow wires) from the digital box to the tv instead. this worked but gave me the humming. for fun, i took a second set of composites and ran them from the box to tv(not through the wall). that fixed my problem and the humming when away. but obviously not what i want as its not in the wall. the composite cable is brand new so i'd think it shouldn't be the problem. the composite cable in the wall has a yellow video cable that is like twice the size as the audio white/red cables where the other set(that works ok) are all the same size. could that give me a potential issue?

Customer:

when the humming is going on, there are also lines in the screen that seem to move from the bottom of the screen to the top. kind of hard to see, but if you look fairly closely, you can see them.

Customer:

they go away too when i switch composite lines.

Anthony's TV :

You have a ground loop

Anthony's TV :

what uses 2 prong AC power and What uses 3 prong AC power?

Anthony's TV :

use a 3 to 2 prong AC power adapter on the 3 prong device (TV?) to break the loop

Customer:

the digital box is 2 prong. the tv is 3. how does that make a difference if when i switch the composite cables to a different set, the humming noise goes away? i'm still using the same devices as before. just different cables. if that works, great, by all means i'll try. just curious why that will work.

Anthony's TV :

ok let me know

Customer:

Ok, so that seemed to work out well. problem seems to be solved. but i'm still curious as to why that worked. can you explain a bit? why was it that with one set of composite cables i had a humming noise, and when i switched them out without changing anything else, that fixed the problem. and then when i switched back to the original composite cables that were humming, and i put the 3/2 adapter in the tv, that also fixed it.

Anthony's TV :

it sounds like you have a problem with the electrical ground in your house

Anthony's TV :

Please have an electricain check it at the at the 2 points you are getting power

Anthony's TV :

As an Engineer for a film studio I deal with this type of issue on set all the time

Anthony's TV :

so i am framillar with it when a lot of techs might not be

Customer:

so are you saying the 3/2 adapter was just a quick check to see what the problem could be? or is this a solution i can use going forward?

Anthony's TV :

It is a solution you can use going forward it breaks the ground loop

Anthony's TV :

but if your house was properly grounded you should nopt have a ground loop[

Customer:

appreciate the help! thanks!

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