Problem: The doorbell doesn’t ring at all, works only occasionally, or rings continuously.
Background: In most all cases the doorbell will be powered with low voltage, fed from a transformer that converts 120-volt household current to the 6- to 8-volt range for older systems, or to a 12- to 14-volt range for newer systems. The low-voltage power supply wire is interrupted by the push button switch at the door. When the button is pushed, the power is fed through to the bell. Weather can corrode outdoor switch contacts, and vibration can loosen connections at the bell.
What to do: Possible causes for the failure include a faulty switch, wiring, transformer, or the bell itself. Chances are best that the switch may be bad, so start there. Unscrew the push button and check to see that the wires are making good contact under the 2 screws behind the switch. If the connections are good, touch a screwdriver between the 2 screws or remove the 2 wires and touch them together. (Normally low-voltage wiring does not carry enough cur rent to be dangerous except at the transformer.) If the doorbell rings, the problem is the pushbutton. Clean its terminals with sandpaper or electrical contact cleaner. If that doesn’t work, replace it; replacements are low cost and readily available.
If, when the wires are touched together, the bell doesn’t ring but the transformer hums, suspect a wiring defect or the bell itself. If the transformer doesn’t hum, suspect defective wiring or a burned-out transformer. Check all wires from the transformer to the push button and back to the bell, making sure connections are good. Inside some bells you may be able to clean the contact breaker points with fine sandpaper or emery cloth. The gong should touch the bell when the con tact points are closed; if not, bend the hammer slightly.
Special advice: If the transformer is suspected, be sure to turn off the master electrical switch before disconnecting because the wires feeding the transformer will be 120 volts. If you are not positive the transformer is bad, have it tested at an electrical supply dealer before buying a re placement.
Helpful hint: To assure your safety in case the transformer has gone bad and is not reducing power to low voltage, use a tester and touch its leads to the 2 screws on the push button switch. A 120-volt tester will not light up if the transformer is reducing the power to low voltage.