In older homes, doorbells are hardwired into the door frame or very near it. They usually don’t present problems for years. But, inevitably, they no longer work and you have to take them apart to repair them.
Wired doorbells have a bell, a junction box with a transformer on it, and the button at the door. Ringing the bell connects the ground wire together, which activates the circuit. But several things can go wrong: loose wires, button defects, short circuits or a power failure, corroded connections, an accumulation of dirt on parts, and malfunctioning bells or transformers. You need pliers, screwdrivers, wire strippers, electrical contact cleaner, fine sandpaper, isopropyl (rubbing) alcohol, and a cotton swab or old toothbrush.
Although doorbells don’t emit much voltage, the transformer is connected to a 120-volt wire in the house. Turn off the power before you start working on the doorbell.
When the bell doesn’t ring, look at the circuit breaker or fuse box. If it hasn’t tripped, turn off power to the doorbell. Now follow these steps:
Check the wires behind the button, in the junction box, and on the transformer.
They may be damaged or loose. If they’re loose, tighten them; if damaged, go to Step 2.
Cut out the damaged area.
If the wires are sound, look for corroded terminals. Remove the plate from the button and look at the terminals.
Strip 1 inch of insulation off the ends of both wires so you can twist them together and then tape them.
If necessary, clean them with electrical contact cleaner. You can also take the screws off the wires and sand off the corrosion using fine sandpaper.
If it chimes continuously, remove the button plate.
Make sure the wires aren’t pinched or touching.
Tighten the screws. Be sure to keep the wires separate.
If the bell sounds as though it’s buried under blankets, it probably needs cleaning. Use a cotton swab or soft toothbrush dipped in isopropyl (rubbing) alcohol to clean it.
Never oil any part of the bell or chime. It will only make the sound worse and may even cause the device to collect more dirt.
The grommets holding the chimes can deteriorate when they get old, causing a muffled sound. Get some new ones and replace the old ones. Also look at the hammer to see whether it’s bent. If so, straighten it out by using pliers. Be careful not to damage it.