Finding internal doorbell terminals

Hello, I recently got a ring doorbell pro and I was working on installing it, one thing I noticed is that my internal doorbell doesn’t actually label the terminals so I’m not sure which terminal is the transformer, which is the front, etc, is there any way I can find out or anything you guys can suggest?

@ChrisV98 wrote:

Hello, I recently got a ring doorbell pro and I was working on installing it, one thing I noticed is that my internal doorbell doesn’t actually label the terminals so I’m not sure which terminal is the transformer, which is the front, etc, is there any way I can find out or anything you guys can suggest?

Hello @ChrisV98 ,

You might be able to “google” a diagram of your internal house-chime online (but you didn’t write the name of the manufacturer/model in your post).

But, if you have the typical “3-terminal” mechanical house-chime, designed for two doors sounds, in every house-chime that I’ve encountered that can make the “Ding-Dong” sound for the Front button and just the “Ding” sound for the Rear button, the Transformer terminal has always been the middle terminal (see attached image). One wire of the transformer attaches to the center terminal and the other transformer wire routes to the doorbell button. Then the return line from the button goes the corresponding outboard terminals on the house-chime.

Some terminals are labeled “Front-Trans-Rear” and some are labeled “Rear-Trans-Front”. So the guess would be, which outboard terminal is “Front” and which is “Rear”. That should be evident as to whether you get the “Ding-Dong” front sound or just a single “Ding” intended for the rear. But don’t worry, you won’t hurt anything if you guess incorrectly and wire the front button wire to the rear house-chime terminal. Then, just switch that outboard wire to the opposite outboard terminal.

You should be able to double-check by using an Ohm-meter, checking the resistance between two terminals. Each solenoids (fancy word for the electromagnet) will have about the same resistance reading between front & trans (outboard & center terminal) . . . or between rear & trans (other outboard & center terminal). You might have to switch/swap the Ohm-meter’s leads due to polarity. If you test two outboard terminals and get at least double the resistance (or higher resistance due to polarity), then you confirmed the outboard terminals are the front & rear (because you are seeing the resistance through both solenoids).

To help make a better educated guess between front and rear terminals (see attached image again), look closely at the springy rod that strikes the “Resonators” (fancy word for the rectangular metal-bell) when the electrical solenoid is energized. The striking-rod that can move to hit both Resonators is the “Front.” The striking-rod that can only move to strike a single Resonator, (since it is inhibited by the “Barrier”), that’s the “Rear.”

I hope this information is helpful :slight_smile:

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