Home intercom continuously buzzing?

Question

The doorbell at the front of the house is an intercom system. The speaker at the front is always buzzing, like there is electrical interference. Have dismantled front panel to no avail. How can I check the wiring, or should I get an electrician

Answer 1

An intercom system such as yours usually has the amplifier in a central location such as the kitchen. The cables that run from the amplifier to each speaker include two conductors for the speaker and several others for the control circuit. The speaker conductors do not necessarily need to be shielded or twisted pair because the impedance is low and the coupling is minimal. I have a Nutone intercom system, which uses a flat ribbon cable. Nothing is shielded or twisted.

Each speaker connected to the amplifier also serves as a microphone when the push-to-talk switch is depressed. Coupling is more of a problem in the microphone mode because the signal level is low. But in the speaker mode, which is most of the time, it is nearly impossible for interference to be the cause for your buzzing.

It is much more likely that the buzzing is coming from your amplifier. A good electronics technician will look for several things. There is first the question whether the intercom has always been buzzing, or is it something that cropped up recently, indicating a component failure.

Second, what is the frequency of the buzzing? If it is 60 Hz, it may well be coupling from a power line. If it is 120 Hz, it is probably a failure in the power supply of the amplifier. If it is another frequency, it would be some other failure in the amplifier.

Third, if your intercom has more than one speaker, does every speaker have the buzzing? Or is it only the front door?

Not all electricians are knowledgeable in electronics. You might be better off to look in the yellow pages for a TV repairman.

Answer 2

Is it an old intercom system? If so, the components of the system might be breaking down and 'leaking'- a condition where transformers and capacitors aren't working efficiently anymore, which causes the buzz you hear. Is the doorbell running off AC? If so, suspect the transformer for the doorbell. A quick drive to Home Depot for a new one will fix that. It usually runs off two wires, but be sure to trip the breaker for that circuit- you're working with line voltage there! If the doorbell is integrated into the intercom system and runs off DC (another design option used), then I would consider the 'old system' for a replacement. Hope that helps!

Answer 3

Electron Intercom

Answer 4

Nutone Intercom Troubleshooting

Answer 5

It sounds like EMI or electromagnetic interference. I would consult with a home stereo system company. They deal with this a lot. You will most likely need a filter of sorts. They are relatively in expensive. You may also need thicker shielding on your speaker wire. This would mean running a new wire. If this isn't practical consider perhaps a wireless intercom. Good luck.

Answer 6

Make sure the wires you are using are shielded and also grounded on one end. If they are grounded on both ends, you may have what's called a "ground loop" which allows electromagnetic interference from nearby transformers, light ballasts or electrical wiring to enter into the intercom wiring.

Answer 7

Get a qualified technician to look at it. Intercoms are complex systems and you don't want to mess with the circuitry yourself or you could end up with a dead unit. Call support if you are still covered by a warranty.

Answer 8

mm i agree with you there is electrical interference. you may need to check out what other electrical products are near the base or reciever

if this does not help check with a sparkie

cheers and hope it helps

Answer 9

more than likely it wasn't installed with twisted pair wire. The other answers were almost correct. It doesn't do any good if the wire is shielded but not twisted pair. shielded twisted pair wire would be the correct wire to use.