A broken doorbell may mean missing out on strangers coming to see you who may be the deliverers of a sweepstakes or a gift. Doorbells also can announce visitors from whom you maybe want to hide. Troubleshooting a broken doorbell can take up a good chunk of time if you aren't used to working with wires and voltage testing equipment, but most homeowners should be able to get the job done fairly easily.
Unscrew the facing on the exterior button that causes the bell to chime. Locate the two connecting wires and check for signs of corrosion or looseness in the wiring itself. Remove one of the two wires from the terminal and press it against either the other wire or the terminal. If the bell rings, you need to replace the button.
Turn off the electricity and clean the metal contacts if there is no immediate wiring cause for the doorbell to stop ringing. Use an old toothbrush to rub the contact points so that they are clean of dirt, dust, grime or oil.
Locate the rubber grommets that are used for suspending the tone bar if the doorbell tone begins to sound strangely dull. The grommets are rubber parts for making the doorbell tone. Although small, they are essential for the doorbell being able to create its proper tone. Over time they can become brittle or even broken. Replace the old grommets with a new one if damaged.
Check the electrical circuits at the transformer that provides power to the bell system. You'll find the transformer attached to 120-volt junction box. Use a continuity tester capable of reading low voltages or expose each end of the copper wires and press one against the exposed terminal screw on the transformer while touching the other bare wire across the terminal screw. If you see a small spark, it means the transformer is good. If the transformer does not test positive for electrical current, cut the power to the junction box, remove the wire leads and install a new transformer.
Remove the chime's cover and pull the wiring free so you can test it using a multi-tester set to the 50-volt AC range to troubleshoot a door chime. Do this.by touching one probe to the transformer and the other to the non-working front or rear terminal. Failure of the test means a wiring problem that needs to be fixed.