Doorbells

Doorbells are simple electrical systems. Repairing one is normally easy and a good lesson in basic electricity—as long as you can find the key components. Because buttons, buzzers, and transformers are relatively inexpensive, replacing these faulty components usually makes more sense than trying to make involved repairs on them.

If you do try to repair your doorbell try the following:

If, when you push the doorbell button, you do not hear a bell, a hum, or even a click, it often means that electricity is not being delivered through the system.

1) Check for a tripped circuit breaker.

2) Check for a burned-out transformer. Turn off the power to the circuit before working on the transformer.

3) Be sure all wires are connected securely at transformer, bell, and button.

4) Remove and check the button. Because the button is the primary moving part of the system, this tends to be the most likely component to fail. To do this, remove the button's attachment screws and gently pull the button out.

Be sure the two wires are connected securely to the screw terminals. Then touch a screwdriver blade across both terminals (or remove the two wires and touch them together).

If the bell sounds, you are in luck; this is a very easy, inexpensive repair. Remove the wires, and clean corrosion from the button's contacts and wire ends with fine sandpaper or electrical contact cleaner.
Reconnect the wires. If the button still does not work, just remove and replace the button (available at hardware stores).

This button test will work if the power circuit is functional. If the button is faulty AND there is an additional problem, it won't. If the simple button test fails to ring the bell, you can make sure the button is faulty by doing a continuity test with an ohmmeter (set on ohms ).
Hold one of the meter's probes on each of the button's contacts, and then push and release the button. The meter's needle should bounce up when the button is pushed and drop flat when it is released. If it doesn't, the button should be replaced