This article explains how to configure a mechanical chime on a video doorbell BEFORE it is online / connected to WIFI. Most doorbells ship with no chime enabled by default, so the use-case for this is an installer that wants to doorbell to ding-dong before the unit is occupied and added to a wifi network.
1. Place the doorbell in AP mode (flashing white LED) by holding down the button for approximately 35 seconds
2. On your phone, connect to the wifi network created by the doorbell: ADC-VDB750 (XX:XX:XX) where XX is the last six digits of the MAC address on the doorbell and packaging.
3. Once connected, open a web browser and go to http://vdb750install (or http://vdb775install if that model), or 192.168.1.1.
4. Click on drop down to show Mechanical chime, then Save. This should program the doorbell to ring the chime. 