Doorbell Repair

“Hey, your doorbell doesn’t work!” “I know! I know! I was going to fix it this weekend.” This Fix-It Guide on doorbell repair tells how a doorbell works, what often goes wrong, how to identify a doorbell problem, and what parts and tools you will need to fix it. It then gives simple step-by-step instructions for how to test the doorbell push button, how to test and replace a doorbell sounding device, and how to test a doorbell transformer.

How Does a Doorbell Work?

A doorbell is a small electric device that signals residents inside when someone outside the door pushes a button. When the button is pushed, it completes a circuit with a transformer, letting electricity through to sound the bell or chime. Some doorbells use a small radio transmitter or a remote controller to activate the bell without wires.

What Can Go Wrong with a Doorbell?

Doorbell Repair

You can test a doorbell with a multimeter.

Loose wiring and faulty buttons are the most common doorbell problem. Power to the circuit may fail. Connection terminals may be corroded. The chime, or transformer may fail. The sounding mechanism may be dirty or the grommets (mechanical chimes only) may deteriorate. The hammer arm may be bent (bells only). The unit may short circuit.


Be careful when working on a doorbell. It may use only low voltage, but the transformer has a 120-volt connection to the house wiring.

How Can I Identify a Doorbell Problem?

  • If there is no sound when the button is pushed, check the electrical service panel for a tripped breaker or blown fuse. Tighten all wire connections behind the button, inside the signaling unit, and at the transformer. Look for damaged wires and splice any breaks by stripping both ends of the wire and joining them with a wire connector. Remove the button plate and look for corrosion around the terminals and clean with electrical contact cleaner or remove the wires from the screws and sand off any corrosion with fine sandpaper. Remove the plate and test the push button (see below). Test the sounding device (see below). Test the transformer (see below).
  • If the bell or chime sounds continuously, remove the button plate and look for touching or pinched wires. Tighten the screws and make sure all the wires are separated.
  • If the signal sounds muffled or faint, clean the sounding mechanism with a cotton swab or old toothbrush dampened with rubbing alcohol (do not lubricate the mechanism). On mechanical chimes, inspect for old or deteriorated grommets that support the metal chime plates. Replace grommets if they are worn. Reshape a bent hammer arm on a bell using pliers gently.

What Do I Need for Doorbell Repair?

Exact replacement parts are available from local home improvement stores, electrical supply outlets, and hardware stores. The tools you will need to fix a doorbell may include these:

  • Screwdrivers
  • Wire strippers
  • Wire connectors
  • Electrical contact cleaner
  • Fine sandpaper
  • Multimeter
  • Rubbing alcohol
  • Cotton swab or old toothbrush
  • Pliers

What Are the Steps to Doorbell Repair?

Fix-It Tip

The first thing to check with a faulty doorbell is the button, especially one that is exposed to the elements. If needed, clean it with alcohol and a cotton swab.

Test the doorbell push button:

  1. Loosen the screws that secure the push button plate. If the plate has clips rather than screws holding it in place, carefully use a flat screwdriver to pry it up.
  2. To test the button, hold the blade of a screwdriver across the terminals. If the sounding device sounds, the button is defective and needs to be replaced (continue with step 3). If there is no sound, test the other components.
  3. Turn off power at the electrical service panel, and disconnect the wires from the switch terminals.
  4. Install the replacement switch by looping the end of each wire clockwise around its terminal screw and tightening the screw. Press the button to test.

Test and replace a doorbell sounding device:

  1. Remove the transformer from its terminal in the unit.
  2. Set a multimeter on RX100 (resistance times 100). Probe the transformer terminal and each button terminal in turn. A reading of infinity or zero ohms means the sounding device is defective and should be replaced.
  3. Turn off power to the doorbell at the electrical service panel.
  4. Loosen the terminal screws, remove the wires, and unscrew the sounding device from the wall.
  5. Insert the wires through the back of the new chime assembly and attach the chime to the wall.
  6. Attach each wire by looping the end clockwise around its terminal screw and tightening the screws.
  7. Install the chime cover, restore power at the electrical service panel, and test the new unit.

Test the doorbell transformer:

  1. With power to the doorbell on, set a multimeter on ACV, 50-volt range.
  2. Attach the tester probes to the terminal screws holding the signaling system wires. If the reading is less than 6 volts or over 24 volts the transformer should be replaced with one of equal voltage.
  3. To replace the transformer, first shut off power to the circuit at the electrical service panel.
  4. Disconnect the signaling system and the house cable wires from the transformer. Install the new transformer leads through the hole in the panel and reattach all wires.