: wired door bell trouble shooting ?

04-18-2013, 04:01 PM
I have a wired doorbell on my house and it quit qorking at both doors. The chime rings once for the back door and twice for the front door.How can I determine if its the transformer or the chime unit ?

04-18-2013, 04:24 PM
Have you checked for low voltage coming out of the transformer?
I'd start there.

04-18-2013, 05:25 PM
If both doors stopped it is either the chime or transformer. Check the voltage at the chime to see if it is getting there, if not check it at the transformer, if it is present at the transformer there is a wiring problem. My guess is that it is the chime, good luck.


04-18-2013, 05:34 PM
I just checked the voltage at the transformer and it read between 0.01 and 0.03
I take it the transformer is shot, right ?

04-18-2013, 05:40 PM
First check voltage on secondary side of transformer should have 12 or 24 volts if you don't open junction box and check and make sure you have 120 volts to primary side of transformer (but be careful) if you have 120 to primary side but not secondary, your transformer is bad. If transformer is good and you have 12 or 24 volts jumper secondary wires (12 or 24 volt) straight to your bell and see if it rings, if it doesn't bell is bad. If it does ring one of your push buttons may be bad find wich two wires go to front door and which to go to back then put meter leads on wires going to front door then have someone go push button meter will ring continuity if wiring and button are good do same thing for back door. If one doesn't ring out take button off and unhook wires from button then check button for continutiy if button reads continuity then wires are bad and need to be re pulled or just go buy a new wireless door bell. Most common problem i find at many houses is the transformer or bell are bad and need to be replaced. Good luck!!

04-18-2013, 06:06 PM
Remember, when you check your voltage at the transformer you are checking AC voltage.

So, when you do your checking be sure that first of all that your meter reads AC voltage correctly. To do this, set your scale to 250 volts ac, and put the leads into a wall socket. You should read the expected 117-122 ac volts.

Then, check both sides of your door bell transformer.

You should have the expected 117-122 volts AC voltage on the primary, where it plugs into the wall, or is hard wired to an ac circuit.

Then, the output of the transformer should be 24 volts AC.

If in doubt, disconnect the chime and button wires from the transformer, and measure the voltage on the transformer again. Sometimes if the chimes go bad, or a short occurs, the voltage on the transformer can be pulled down to 0. So, to check that, disconnect the door bell chimes from the transformer and recheck the AC voltage on the transformer.

But, if you have already said, have no voltage on the transformer with no wires connected, but have good 120Volts on the transformer primary, the transformer is certainly bad.


04-18-2013, 07:13 PM
There is only two wires attached to the transformer out put that I can get to test, they are right out in the open. I checked the transformer where the wires are attached that go to the door bell. I was under the impression the out put should be DC current.
REW are you saying the transformer out put should be AC ?

04-18-2013, 08:12 PM
Doorbells r 12or 24V AC. Typically 12. 90% of the time it is a bad transformer.

04-18-2013, 08:53 PM
Rebs- my doorbell did the same thing, and I found that replacing it with a wireless unit from the local home center was the best and easiest option.

Now, its always a mystery to see what chime my son has it set to when someone comes over. This darn doorbell has a chime for every holiday and season, its kinda funny.

Good luck with yours!

04-18-2013, 09:11 PM
Rebs- my doorbell did the same thing, and I found that replacing it with a wireless unit from the local home center was the best and easiest option.

Now, its always a mystery to see what chime my son has it set to when someone comes over. This darn doorbell has a chime for every holiday and season, its kinda funny.

Good luck with yours!

Yup. Bought a new house and the transformer is buried somewhere under the suspended ceiling......looked for it in all the conventional locations.. then went out and bot a wireless. Works like a chime.

04-18-2013, 10:09 PM
Yes, the transformer is exactly that.
It is a device that is used to "Transform" 120 volt ac voltage to either
12 or 24 volt AC voltage.

i.e. not change it to dc voltage, but just change the voltage level from the high 120 volts to the lower 12 or 24 volts.

04-18-2013, 10:17 PM


This one gives some nice lessons on meters and testing for your door bell issue:


04-19-2013, 04:27 AM
I checked it again, this time I checked for AC and it reads 15.6 volts so its not the transformer.

04-19-2013, 09:01 AM
Still no luck with getting it to work.
You guys that have the wireless doorbell, what brand or model do you recommend.

04-19-2013, 10:36 AM
Do you have 15 volts at the door bell when you have someone else push the door bell button.

A door bell is a very basic appliance.

1. Have a source of 110volts AC
2. Have a transformer to drop the AC voltage to the AC voltage required by the bell.
3. Door bells are wired different ways. But many door bells use a pair of wires to run the voltage to the door bell. Then, a wire is run from each door to the door bell to activate the door bell.

If that is the case with your door bell, just go to the door bell and short across the two terminals that run to the door bell button and see if the door bell works. If the door bell works when you short the two bell button contacts, but does not work when you press the button, you either have a bad button; or a broken connection or wire between the button and bell.

3a. Other door bells are wired in series. i.e. they run two wires out of the transformer. One wire runs to the bell. One wire runs to the bell button. Then, a wire is run from the button to the bell. Now, when the button is pressed, the circuit is completed and the bell rings.


Take the cover off the door bell. Look at the connections and wires coming into the bell. If you have one pair of wire that is marked transformer or input voltage, use the meter to check for the presence of the same 15 volts that you had on the transformer. If you have the same voltage on the bell, your transformer is all right, and the wiring and connections from the transformer to the bell are all right.

Now, look for the contacts that run to the bell button. If you have a pair or pairs of contacts for one or more buttons, just use a jumper wire to short across any pair of buttons to see if the bell rings. If the bell rings, the bell is all right and the problem is in the button or button wiring.

But, if the bell does not ring, but has ac voltage and if you remove the button wiring from the bell and use the meter set on ohms scale, and then put one meter lead on each of the leads - you should find infinite ohms when the button is not touched. Then you should find close to 0 ohms, or a short, if the button is pressed.

If all of the above is true, buy a new door chime and replace it. Wire up the transformer and button wire/s and you should be good to go.

A few years ago, we were in a home building big box store and came across a very high end door chime mounted on a display board. The board was not hanging up, but was simply sitting on a shelf. So, I asked the store person, if the chime was for sale. He said, "sure, this was a display, and is no longer being used." So, I said, "how much". He looked for about 15 minutes and said, "I finally found the original price for the chime, and it was selling for $280."

I said, all right, that is fine, but what you will sell me this display model for?

He said, "How about $5?"

Of course, I said ,"sure".

We took the set of chimes home and I took about 15 minutes to remove the old door bell chimes and mount the new set of chimes.

Lovely 7 tone chimes, that play a different tune for each door.

Never know what one runs across.


04-19-2013, 11:49 AM
Rebs- I think this is one similiar to the one I bought 2 years ago, and it still works:


Good Luck!

04-20-2013, 02:06 PM
I worked on this door bell long enough. I think there is a problem with the wiring and its not worth trying to trace the wires through the walls. I went to Home Depot and bought a Heath Zenith wireless one, it works great, has different sounds and a volume control. Now I hope it lasts a while.

Thank you to all you guys for the help.
REW thank you for all your info and help.

04-20-2013, 10:10 PM
As the saying goes, I am glad that you have a working ding a ling again.

04-21-2013, 06:59 AM
Thanks REW, this heath zenith one seems to work quite well, now to see how long it lasts. Reading the reviews on wireless doorbells was not too much help. Everyone has an opinion and when you go in the stores the sales people have an opinion and they don't match up. I guess just pick the one you like and give it a try.