How to Check Your Doorbell Transformer

Introduction:

Doorbells seem to work forever but they do fail from time to time. Many homeowners just ignore the doorbell when it fails, leaving visitors to just rap on the door to announce their arrival. That will work if you are expecting company but if you are not, you may be somewhere in the house where you can’t hear someone rapping at your door.

Repairing your doorbell is an easy DIY task. In most cases when the doorbell fails, it is because the transformer has failed. If there is no light on in the doorbell button then it is almost certain that the transformer has failed. The first step in the repair process is to find the transformer and determine if it is still supplying power to the doorbell.

How to check your doorbell transformer:

Finding the doorbell transformer can be a challenge. In most houses, it is located on the main electrical panel; however, in some cases it is internal to the doorbell chimes box or bell enclosure. If the transformer is not located on the electrical panel, trace the doorbell wires back to find the transformer’s location. It may be mounted on a floor joist in the basement, in a closet or in the attic.   

The voltage rating should be stamped on the transformer or on the data plate of the doorbell mechanism. In most cases it will be 16 volts, however, older transformers may be only 12 volts.

How to check the transformer:

1.    Set a volt-ohm meter scale to 25 VAC.

2.    Attach the two probes to the two flat screws on the transformer where the small-gauge doorbell wires are attached to the transformer.

3.    Compare the voltage reading to the device’s voltage requirements. If it reads 0 or exceeds 16 volts the transformer needs replacing.

4.    Shut off the power to the transformer by turning the circuit breaker off before performing anymore work on the doorbell system.

Replace the transformer with a new one. Doorbell transformers are readily available at most home supply centers.

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