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doorbell, transformer, and chime troubleshooting with a multimeter

doorbell, transformer, and chime troubleshooting with a multimeter

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  #1  
Old 08-31-20, 07:44 PM
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doorbell, transformer, and chime troubleshooting with a multimeter

Hi Doityourselfer's!

I have a couple of questions related to fixing an unresponsive doorbell and hoping someone can help. My Ring video doorbell, which I installed a couple of years ago, worked fine up until a couple of weeks ago when it abruptly stopped working and is no longer getting any power. I'll include some pics which might help. Please feel free to ask me any questions if you need any clarification, and thanks in advance for any help!

So, I suspect that one of three things is happening with the doorbell. Either the doorbell is dead, the transformer is dead, or there is a problem with the chime. In troubleshooting I first detached the doorbell and after switching my multimeter to the 200 V~ setting, touched each probe to each doorbell wire and got a 0 reading, leading me to believe there was no power coming through the wires. So, I surmised there may be a problem with the transformer. I tested the screws on the transformer and also got a 0 reading. So, I switched off the circuit feeding power there and disconnected the transformer, which is rated at 16V. I then switched the multimeter to the continuity setting and did get a sound when I touched each probe to each transformer screw. Hmm, so maybe the transformer is fine?

Next, since I have a second doorbell that I also want to power, and I know the Ring can take a lot of power, I bought a new transformer which is 24V in order to make sure it can easily power both doorbells. This leads me to my questions. First, before installing the new transformer, I wanted to verify that there was indeed 120V coming from the house wires where the transfomer gets installed. With the power off I separated all the wires (ground, black and white) and after switching the power back on I used the 200 V~ setting on the multimeter to touch the black probe to the copper ground wire and the red probe to the white wire and then the black wire. Mostly the multimeter read 00.0 but at times would briefly read 00.1 or 00.2. Is this normal? I was expecting 120 and didn't know what to make of the readings I got. What am I doing wrong? I know the multimeter works because I was able to successfully get a 120 reading be testing an outlet.


trying to test voltage of house wires which connect to the doorbell transformer


I was getting either 00.0 or 00.1 or 00.2 when testing the house wires using the 200 V~ setting on my multimeter


My next two questions relate to the doorbell chime. Thinking that since the 16V transformer continuity test checked out, perhaps the problem was with the chime? So, I checked it and noticed one of the chime wires seemed loose. Unfortunately, when I removed some of the electrical tape that was keeping things in place, it became unclear which doorbell wire (front or rear) went to which chime connector. Is there a way I can test to see which wire goes to which doorbell and also verify which is the correct wire to go back to the transformer?



This is a Broan-NuTone BK125LWH-1 16VAC doorbell chime.

Finally, I see the chime is rated at 16VAC, but would it be safe to connect it to the new 24V transformer I bought (which is this transformer -> https://www.amazon.com/gp/product/B07Q4PPKQ8)? I got a 24V one because I read it was recommendeded to make sure it can power both the Ring doorbell and my other doorbell as well. I'd like to avoid having to get a new chime if it isn't necessary.

This little bit of troubleshooting has turned into a bit of a project. Hoping someone can help. Thank you.
 

Last edited by PJmax; 08-31-20 at 08:00 PM. Reason: resized pics
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  #2  
Old 08-31-20, 07:51 PM
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Welcome to the forums.

Your transformer was probably cold.

There are two windings...... the 120v primary and the 16.5v secondary.
You checked the secondary and it had continuity.
More that likely the 120v primary was open due to a line surge or spike on the AC wiring.

When you check for AC power...... one lead to black and the other to white.
There is no polarity to the leads as it's AC.
.1 on the meter is a miscellaneous or ghost voltage common with sensitive digital meters in AC mode
In your case..... it was equivalent to 0v.

25v is a little large for the chimes. Are you running two chimes off of one Ring ?

It looks like red should be TRANS on the chime. You'd have to try the front and rear experimentally.
 
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Old 09-01-20, 11:24 AM
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Hi Pete,

Thanks a lot for your reply, really appreciate the guidance.

I think you're right about the transformer as we had a brief power outage here around the time the doorbell stopped working.

So, I just tested continuity on the 120V side (the white and black wires) on the original 16V transformer and got the AOK sound from the multimeter. When you say the 120V was open, what does that mean for the transformer and do you think it is still usable? I'm wondering if/when we get another surge or spike how I should cope with it? Unfortunately I don't see a trivial way to protect the transformer with a UPS unit (or surge supressor) or something like that, which is what I use for all my computer equipment. Any ideas?

I got the new 24V transformer to power one chime and two doorbells - currently one video doorbell but I might also replace the second doorbell with a video unit as well. Apparently these doorbells like to draw a lot of juice. Will the 24V transformer cause a problem for the 16VAC chime? I don't want to start a fire.

Good call on the wiring in the chime. I just noticed the red wire is single whereas the black and white ones have two parts which makes sense for the doorbell connections.

Thanks again for your help!
Cheers,
Dave
 
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Old 09-07-20, 07:52 PM
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So, it looks like there may be a problem with my wiring. Would be great to get a second opinion on this though...

I bought a non-contact voltage tester (Klein Tools NCVT-2) and brought it near the exposed wires which were powering the transformer. The tester showed no indication of any voltage on the wires.

This is a brand new NCVT with fresh batteries and it tests normally elsewhere and shows voltage on multiple other sources such as the associated circuit breaker to these wires and also other outlets.



testing voltage on what was expected to be a live wire using a Klein NCVT-2 voltage tester - a detected voltage should turn the detector's LED red

Here is a test of the associated circuit breaker which causes the tester to blink red showing live voltage.




Should I conclude from this failed test that my wires are now faulty?

Thanks in advance for any thoughts on the matter.
 
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Old 09-08-20, 12:12 PM
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If the breaker is showing power and the wiring is not..... the wire may have fallen out of the breaker.
If you're comfortable.... remove the panel cover and check it out.
 
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Old 09-08-20, 12:39 PM
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Have tried shutting the breaker Off , all the way to the left and back on?
Geo
 
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Old 09-10-20, 03:38 PM
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Thanks so much for the replies!

I did shut the breaker off and on, but I'll try that again before proceeding. There are actually two outlets on that wall and one of them is powering a fridge, so I know the breaker was fully off because the fridge lost power.

I will plan to power off the house at the master breaker this weekend and take off the panel to check the wiring to the breaker powering the wiring to the transformer. Without taking a chunk out of the wall, is there a way I can tell if the wiring goes directly to the circuit breaker or if it comes from the other outlet?
 
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Old 09-10-20, 10:27 PM
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It looks like only two wires in the transformer box. That means the wiring could come from the other receptacle but in your application..... both wires may be connected on one breaker.
 
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