Ground Loop Diagnosis

[John Denison]

Can you diagnose a possible ground loop problem with one of those little 3 prong wall plug electrical testers that you plug into the wall and has the 3 lights across the top? I'm working on a sub woofer hum issue.

 

[roberto]

Can you diagnose a possible ground loop problem with one of those little 3 prong wall plug electrical testers that you plug into the wall and has the 3 lights across the top? I'm working on a sub woofer hum issue.

Hola John. Usually the ground loop problem is due to the cable antenna ground connection and your home ground. Just a tinny potencial difference at the cables in the ground, 60Hz are induced. Disconnect the cable antenna from your tv and listen if the hum goes away. If it does, then you can use a special device that it is connected between your cable signal and your tv. This will put away the hum. Using a cheater plug (the plug that converts three pins in two) sometimes helps. Try is first at your TV. Perhaps this can help...happy listening,
Roberto.

 

[risabet]

Can you diagnose a possible ground loop problem with one of those little 3 prong wall plug electrical testers that you plug into the wall and has the 3 lights across the top? I'm working on a sub woofer hum issue.

No, a circuit tester will tell you if the outlet is wired improperly, hot and neutral reversed, ground not attached, but not if there is a ground loop. If a video system is connected than Roberto gives good advice. Unhook the cable and see if the hum goes away. If so, than a Jensen VRD-1FF Cable TV Ground Loop Isolator http://www.jensen-transformers.com/ is the way to go. You can also try floating the 3 pin power cords using a cheater plug.

 

[Spike]

Another (cheaper) option

Parts Express carry a cheaper isolation transformer which works well to eliminate hum: Dayton Isolation Transformer.

Spike

 

[beefchowmein]

maybe slightly off topic of the original poster. Just curious maybe someone here might know. My house is old and as far as I know it doesn't have the ground. All outlets are 2 prong. Does that mean I would potentially get a better sound with less interference? I know it's probably not safe without the ground in the house. It's on the to do to get all the wiring replaced.

 

[aliveatfive]

If your house uses metal shielded (bx) cable, you may use grounded outlets in which the ground may be connected to the outlet box. There are some duplex outlets which make that connection just by screwing them into the existing box. BTW, some of those isolation transformers will not pass a high-definition tv signal.