I recently installed my ADC VDB750 doorbell with a 16V 30VA doorbelll transformer, and all was fine and working for a week and a half. I wasn’t getting a chime notification from the IQ4 panel, so I tried changing the doorbell chime settings in the Alarm.com app and testing the doorbell by pushing the doorbell button.
After the second doorbell button press, the doorbell was no longer powered. I felt the doorbell transformer and it was super warm, so I figured it was a bad transformer and got burnt up. I bought a new 16V 30VA transformer, and tried to reconnect the doorbell, but immediately the transformer got super hot and no longer output any voltage.
I powered the doorbell via the micro usb cable, and it powered on correctly, so I undid the settings changes to the doorbell. I bought another transformer (different brand) and tried again. Before reconnecting the doorbell, I verified the voltage was 18V out of the transformer and also 18V at the doorbell panel. The same issue occurred that within 10 seconds of re-installing the doorbell, the transformer no longer was outputting 18V and now read basically 0V.
Do I just need a new doorbell camera? I find it hard to believe that changing the doorbell settings and ringing the doorbell would cause a short like this, but I don’t have any other ideas of what could be wrong.
I actually don’t have a chime connected currently, which is why it was set to no chime. I was trying to get the IQ4 panel to chime instead, but I guess changing the settings somehow shorted the doorbell? It’s just the 2 transformer wires connected to the doorbell.
Following the thread’s suggestions here ( Doorbell Chime options - #3 by jwcsurety ), I enabled the live stream to the iq4 panel. That seemed to work fine, but the chime still didn’t play. After troubleshooting more, I tried changing the doorbell chime setting itself to a digital chime, and that’s when the doorbell was no longer powered.
Changing the chime settings on the doorbell changes how it behaves. I’m not familar with the exact changes; however, digital chimes require an extra module to regulate the power going to the speaker on the chime, so that could be a factor.
I’ll need to reach out to Alarm.com tomorrow to help determine what kind of effect this would have on the doorbell itself, but if it continues to burn up transformers despite the settings being changed back, then the doorbell itself might have experienced damage at the hardware level.
If you’re using an Alarm.com Smart Chime or the panel for chime notifications, then you would select the no chime option.
You can enable doorbell chime notifications for the panel in Alarm.com. It is found in Video > Settings > Select the video doorbell > General Settings. Select the Panel Button Press Notifications option to enable it.
What is the VA rating of the 2nd transformer you put in? The power requirements for an ADC-VDB750 are 16-24 VAC, 10-40VA for AC transformers and 15-24 VDC, 6-20W for DC transformers. If the transformer meets the power requirements, then the issue may be with either the doorbell itself or the wiring leading to the doorbell.
Would you be able to power the doorbell on via micro USB and connect it to Wi-Fi so that Alarm.com can run some diagnostic tests on it?
All the transformers were 16 VAC 30 VA AC transformers. The wiring was newly run 18/2 wiring, approximately 10 feet long. The input to the transformers was tested to ensure it was properly grounded via the ground wire in the 12/2 romex.
Transformers (unsure if external links are allowed, but this should let you find them):
2x Defiant Wired 16VAC/30VA Doorbell Transformer Model # 18000044
1x Heath Zenith Silver Metal Wired Door Chime Transformer Item # 3004016
I’ve powered the doorbell via the micro USB and it’s connected to the Wifi. I can see the camera feed through the Alarm.com app. Let me know if you need any additional information.
Could you post a photo of the wiring at and behind the doorbell? What is being described sounds like a physical short circuit.
Installing and pressing the doorbell button may be placing pressure on the wires and falicitating that short, depending on how they are routed behind the doorbell.
The shorting of the transformers/doorbell didn’t start until after changing the settings. The doorbell was rung at time of installation multiple times and on a few days after by delivery drivers.
Is there any way to fix the doorbell without ordering a new one, or confirming what the issue is without burning up another transformer?
Thanks, yes that shows plenty to verify it is not likely wiring related. I wanted to be sure we rule that out.
Changing the doorbell chime setting to Digital unfortunately would be the cause. When you do that it results in the expectation that there is:
An appropriate chime load wired to the circuit
The power module connected to regulate the power.
If the doorbell expects a chime and there is no chime connected, then the doorbell button is just shorting the transformer wires when pressed. There is no load in between the two sides of the circuit in that scenario, both wires just lead directly back to the transformer.
so I undid the settings changes to the doorbell. I bought another transformer (different brand) and tried again. Before reconnecting the doorbell, I verified the voltage was 18V out of the transformer and also 18V at the doorbell panel. The same issue occurred that within 10 seconds of re-installing the doorbell, the transformer no longer was outputting 18V and now read basically 0V.
I do see that the doorbell last reported No Chime selected in settings, so if the behavior continues with new transformers and the correct setting selected, even without pressing the doorbell button, and there are no physical wiring issues, that suggests that the doorbell’s internal power circuit has been damaged by the heat build up before the transformer failed, causing a short somewhere on the board.
Unfortunately there would not be a fix for that condition. That doorbell should be discarded as it may be a fire hazard if reconnected, and a new doorbell would be required.
This is an unusual circumstance but your description sounds like this may be what happened.
