Home Repair Tips – Doorbells

Filed Under: DIY Outdoor, Do it yourself, Electrical, Home repair    by: ITC

The doorbell system has four working parts:

• Push button


Electromagnet and striker

• Bell or chime

A doorbell push button is simply a switch with a spring inside. Pressing down on the button completes the circuit. When you release the button, the spring pushes the contacts open and cuts off electrical flow.

A transformer is a device that changes voltage. There are two basic types of transformers:

• A step-up transformer, which increases voltage

• A step-down transformer, which cuts down voltage

A doorbell transformer is the step-down type. It takes 110-volt current and reduces it to a low voltage of 8 to 20 volts. This low voltage output operates the doorbell. Eight to 20 volts is relatively safe. The high voltage wired into the other side of the trails- former is dangerous.

When you push the doorbell button, electricity flows through an electromagnet which attracts a striker. As the striker moves, it hits the bell or chime.

If the doorbell is not working, first inspect the wiring. Splice any broken wire or replace it with No. 18 bell wire.

Probably the most common problem with doorbells is the push button because it must stand up under constant use and weather conditions. To check it, remove the mounting screws and inspect the back. Clamp a piece of wire with alligator clips across the contacts. If you don’t have alligator clips, hold a piece of wire by the insulation and touch the bare ends of the wire to the contacts. If the doorbell rings, the push button is faulty. First try cleaning the contacts with steel wool or fine sandpaper. If that doesn’t work, replace the push button.

When you bypass the switch and the doorbell still does not ring, the problem is somewhere else in the circuit. Next test the transformer at the low voltage side. This is the side connected to the wires that run to the push button and the bell. Test it with a low voltage circuit tester. A 110-volt tester will not work. If the circuit tester lights, the transformer is working and the problem is with the doorbell or chime itself. If the tester does not light the transformer is bad and must be replaced with one of the same voltage. Turn off the electricity. Loosen and remove the locknut behind the transformer. Replace the trans voltage. Remove the wires and attach the new transformer in the same way the old one was attached.

If the doorbell or chime itself is the problem, you may be able to fix it. Check the wires connected to the bell or chime unit to make sure they haven’t come loose. You may have to bend the striker slightly so that it will make contact with the bell. If the chime unit has a plunger, cleaning the plunger may help it move more freely. Do not oil the plunger because oil will attract dust, and before long the plunger will be sticking again. Lubricate with silicone spray or graphite. If you cannot repair the chime or bell, it is easy and economical to replace it.

There is a locknut at the back of the transformer. After you have turned off the electricity, loosen the locknut by tapping with a hammer and screwdriver. Then unthread the locknut by hand. Be sure the replacement transformer has the same voltage.

Doorbells and chimes have the same basic working parts. A bell, though, also has a set of contact points that are pulled apart each time the electromagnet draws the striker. This opens the circuit. A spring pulls the contacts together again and the cycle repeats as long as the pushbutton is held. This is why doorbells keep ringing and chimes only sound once.

The input side of a transformer is connected to the 110-volt house current. The two contacts on the output side give 8 to 20 volts to operate the doorbell.

The doorbell push button is a spring switch kept in the open position. Pushing down on the button completes the circuit and sounds the bell or chime. Doorbell push buttons are for low voltage. Do not use a doorbell push button in a high voltage circuit. Ithom can arc and start a fire.

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