A humming doorbell is a common problem that is easy to fix. Since the button is used so often, it can get damaged or partially stuck in the contact position. The humming is usually caused by the button being stuck in the contact position. You can stop the humming by replacing the button. You do not have to be familiar with electrical systems to replace the button.
Make sure you purchase the same button you are replacing. The new button should include a faceplate and screws. It is important to buy the same button assembly to avoid having to drill new holes into your house. Bring a photo of your current doorbell with you to the hardware store for comparison. If you still aren't sure, follow the steps below but stop after you have removed the button, then bring it to the store with you.
Step 1 - Turn Off the Power
If you know which breaker controls the power to your doorbell, turn it off. If you are unsure, you can either turn off the main breaker or test which breaker controls which room until you find the right one. The voltage used by the transformer for a doorbell is low and safe for human contact, but you have no way of knowing the voltage being used, so it is better to be safe by turning the power off.
Step 2 - Unscrew the Plate
Using the appropriate screwdriver, loosen the screws on the plate of the doorbell. The plate has 2 screws, one above the button and one below.
Step 3 - Remove the Plate and Button
Pull the plate out gently. The button will come out with the plate. Turn the plate over. The wires that connect the plate to the transformer or terminal may be wrapped around screws. Loosen the screws and remove the wires. If the wires are clipped in, cut them using the wire cutter.
Step 4 - Strip the Wires
If you cut the wires in Step 3, you need to strip the ends about ½ inch to prepare for installation of the new button. If the wires were wrapped around the screws on the old plate, you do not need to strip the wires unless they seem damaged or broken.
Step 5 - Connect the Wires
Take your new button and plate and turn it over. The wires need to be attached how they were on the old one. Use the new screws that came with your replacement doorbell button. If the wires were wrapped around the screws, place the screws in the holes and wrap the wire around them. Then tighten the screws until the wires are secure. If the wires were clipped in, clip the exposed wire in the same place. You may need to use pliers to wrap or clip the wires.
Step 6 - Replace the Button
Screw the wired faceplate on the house.
Step 7 - Turn Power On and Test
Turn the power back on. Listen to the doorbell before you push it. You should no longer hear the humming sound. Push the doorbell to make sure it works. If you don't get any power, test the transformer to see if it's getting any power.