When your doorbell or door chime doesn't ring, the fault could be in any part of the circuitry -- the button, the bell or chime, or the transformer. The transformer is the electrical component that steps down the 110-120-volt current to the 10 to 18 volts at which doorbells and chimes operate. You can work safely on all parts of a doorbell circuit except the transformer without disconnecting the power.
Head over to the next page for the first step.
Remove the Screws
Remove screws that hold doorbell push button to your house.
Remove the Button
Pull out button as far as circuit wires allow, then detach wires by loosening terminal screws on button. Bring the two bare wire ends together. If bell rings, you know fault is in button. Install new one by connecting the two wires to terminal screws of new button and reattaching button to your house. Doorbell button is a single-pole switch (two wires attached), and you can place either wire under either screw.
Check Other Problem Areas
If bell doesn't ring when you bring the two bare wire ends together, fault lies elsewhere -- in bell or chime assembly, wiring, or transformer. Remove snap-on cover of bell or chime. Removal may be harder than you expect; there are several different types of covers, and you may have to try several procedures. Try lifting cover slightly upward and then pulling it out. If this doesn't work, pull it straight out without first lifting it up. Or look to see whether snap-on cover is held to bell or chime assembly with prongs; if so, depress prongs and pull cover to release it. Whatever you do, never pull so hard that you risk damaging decorative cover.
Test the Wires
Once cover is removed, look for two, three, or more terminals and wires, depending on how many tones ring in your doorbell system. A standard bell or buzzer has two wires. Detach wires by loosening terminal screws, then connect them to 12-volt circuit tester, or attach them to terminal screws on substitute bell or chime. An inexpensive bell or buzzer or a 12-volt car lamp bulb in a socket with two wires can be used for testing purposes. If test bell or buzzer sounds or bulb lights when you push doorbell button, you will have to install new bell or chime.
Test the Terminals
If you have a chime assembly with three or more wires, tag them with masking tape: "T" for transformer, "2" for front door chime, and "1" for the back door chime. Loosen terminal screws, remove all wires, and connect wires labeled "T" and "2" to screw terminals on test bell or bulb. If test bell rings or bulb lights when you push front door button, old chime set is faulty. To check this conclusion, connect wires labeled "T" and "1" to screw terminals on test bell. If bell rings when you push back door button, then you're certain chimes must be replaced.
Check the Transformer
If bell doesn't ring or bulb doesn't light at button or bell box, both are okay. By process of elimination, you now know problem must be in transformer or wiring. You'll usually find transformer mounted on electrical junction box, subpanel, or main entrance panel. Bell wires are attached to exposed terminal screws on transformer. Connect test bell directly to exposed low-voltage transformer terminals; don't touch any other screws. If bell doesn't ring, transformer is defective or not getting power. Caution: Transformer is connected directly to power supply, and it carries current that can hurt you. Before working on transformer, deenergize branch circuit that supplies power to transformer. Remove appropriate fuse, trip correct circuit breaker, or throw main switch to shut off all electricity in your home.
Check the Transformer Power
Before replacing transformer, check to make sure it's getting power from the 110-120-volt circuit. With circuit deenergized, disconnect transformer from line wires. Then turn circuit back on again and touch probes of 110-120-volt circuit tester to bare wire ends. If tester light glows or indicator reads 110-120 volts, circuit is okay.
Remove the Faulty Transformer
If transformer is defective, deenergize circuit, and remove transformer. Buy replacement transformer of the same voltage and wattage. You can find electrical information stamped on transformer, and you should find installation instructions on package. Follow instructions carefully. Use crimp-on connectors or wirenuts to attach new transformer to circuit line wires of your electrical system. Then connect bell wires to low-voltage screw terminals on transformer, turn power back on, and press doorbell button. If you've installed transformer properly, you should hear bell or chime.
Check the Bell Wiring
If transformer and its power circuit prove to be working, the only possibility left is a break or loose connection somewhere in bell wiring. Trace bell circuit from transformer to bell or chime to push buttons, searching for loose terminal screw or wire joint. If this proves unsuccessful, you'll have to check each segment of circuit with continuity tester.
Check the Bell Circuit
To test each segment of circuit, disconnect bell wires at transformer to deenergize bell circuit. A continuity tester can never be used on an energized circuit. Disconnect transformer wires at bell or chime, and twist them together so they make contact with one another. Go back to transformer and touch probe leads of continuity tester to bare ends of bell wires. If tester lights up or you get a reading on meter dial, circuit has continuity and there are no breaks or loose connections in line. That part of the circuit is all right. If tester does not register, there's a break somewhere. If that segment is fault-free, go on to next segment and check it the same way.
Reasseble the Doorbell
If there is a break, you must try to locate it and make repairs. Sometimes, however, especially where much of the bell circuit wiring is hidden within walls or is otherwise inaccessible, the easiest course of action is to run new segment of bell wire along whatever path is easiest and forget about old wiring segment.
Old houses have an undeniable charm, but there are inherent issues that can turn owning one into a nightmare. Knowing what to watch for is key.