VDB770 failure after power outage

I had an odd power outage today where the power dropped to a level that most devices shut off but some low voltage devices (night light, alarm panel, and doorbell) remained on. This was followed by a complete outage.

After the power came back on, my doorbell did not. I went through the troubleshooting steps of holding down the button for 40 seconds and resetting the breaker, none of which brought it back to life.

Finally I removed the doorbell and connected it to microUsb. Voila, it came on. When I put it back in place everything worked normally.

What could have gone wrong here and what can I do to prevent this in the future? Of course, if I’m away for some extended period and this were to happen, I need it to come back online.


It is very difficult to anticipate unexpected errors due to unusual home power fluctuations. There is not really anything that you can do in terms of the doorbell product or settings to handle power surges differently.

One thing that can be done is to try and isolate the power supply from the fluctuations. You could potentially use a plug-in transformer with the same electrical specs for doorbell power and use an UPS for a more stable power application and power loss when fluctuations occur.

Thanks. One potential issue is that I noticed I’m still using the power module from a previous smart doorbell. I don’t think this is what caused this issue, but could you provide guidance on how I can replace this with the ADC module?

My 2nd chime does not have a power module and it seems that ADC requires one on all chimes. What should I do about that? Will I be fine without a power module on that chime? The previous doorbell was professionally installed so I would assume this configuration is ok?

Chime 1:

Chime 2:

Yes, you will need to use the Alarm.com VDB770 power module, and if you have two chimes connected to it there are specific instructions and two modules are required. See below for instructions on how to wire it: