just installed my pro 2 and it's making a loud, constant buzzing or humming sound from the chime inside my house

Diagnosis

The mechanical chime is vibrating because the Pro 2's power kit is not properly installed or is incompatible with your specific chime type.

How to Fix It

Reinstall the power kit correctly for your chime.

1. Turn off power at the breaker.
2. Identify your chime: it's either a mechanical (has a physical plunger that strikes a bell) or digital (makes a digital tone).
3. For a mechanical chime: the power kit's two wires must be connected to the 'Front' and 'Trans' terminals on the chime. The doorbell's wires go to 'Front' and the transformer terminal.
4. For a digital chime: you must use the bypass cable that comes in the box instead of the power kit. Connect the bypass cable between the two chime terminals.

If That Didn't Work

The buzzing could be from a failing or overloaded doorbell transformer. Even if it's the right rating, the transformer itself could be faulty. Try a new, high-quality 30VA transformer.

Heads Up

Never install the power kit on a digital chime. The buzzing can damage the chime's electronics. If you have a digital chime, the bypass cable is mandatory.