# Doorbell transformers keep blowing



## preciouschristy (Jun 14, 2009)

A couple of years ago I disconnected the doorbell wires and bought a wireless. That stopped working, and rather than invest in parts for it- I decided it would be cheaper in the long run to hook the wires back up. Unfortunately, I've now invested in two new transformers which have both blown within minutes of me hooking them up.

I'm not sure if I have the chimes and button wired correctly (since I had to reconnect them), so could that be why the transformers are blowing? The second time it did seem to be working (the light on the button came on), but before I could test the system, I was distracted (by twisting my ankle). Once I got up to finish the project, the transformer had blown.

Does anyone have any ideas on how I can troubleshoot this problem, or am I just going to have to rewire the whole darn thing?


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## Jump-start (Sep 26, 2012)

Either the transfomer is being hooked up to 240 or the secondary is shorted, although with some makes I have seen the secondary stay shorted for sometime without issue. But anything is possible. 

Any specific details on the transfomer?


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## preciouschristy (Jun 14, 2009)

The transformers are standard 16VAC/10VA transformers- same as the instructions for the chime indicate. The input should be standard 120V, but I do worry that the circuit I'm tapping already has too many things tapped into it (there are already three other lines branched off).


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## Jump-start (Sep 26, 2012)

The tapping on the 120 vac wont do it. Most likely a short circuit on the secondary.


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## preciouschristy (Jun 14, 2009)

Great- sounds like another trip into the attic for me. Sigh.

Thanks for the help-


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## dmxtothemax (Oct 26, 2010)

If it is blowing within minutes ?
Then you have a serious overload situation 
double check all your wires and splices
or anywhere there are wire connections
If that doesn't show up any problems
then disconnect the bell and measure the 
resistance of the wires leaving the tranny
it should be very high.
If it is low then you could have a shorted cable 
run some where.

Let us know what you find
no matter how silly you feel.

:thumbsup:


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## Piedmont (Nov 1, 2007)

Had this happen to me. In my case when I bought my house the doorbell didn't work. I replaced the transformer and it blew in minutes. Replaced it again (my doorbell transformer is attached to the side of my breaker panel) turned on the breaker for a second or two and shut it off and the transformer was incredibly hot! I then let it cool and disconnected the back doorbell from it so it had only the front doorbell attached, turned it on for a few seconds and it was cool to the touch afterward. Since I don't use the back doorbell I left it disconnected, but obviously was a short.

Some years later I found in the attic a nail going through the doorbell wire to the back door while adding insulation. That was the culprit.


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## preciouschristy (Jun 14, 2009)

Thanks everyone for the help- I did discover the problem- when I re-hooked up the wires, I inadvertently connected both wires from the transformer directly to the button, without a leg to the chime (the wires from the chime were buried under insulation, so I originally thought they must be in the wall). When I re-routed the wires, it worked!

Thanks again- you totally helped me figure it out


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## petey_c (Jul 25, 2008)

preciouschristy said:


> Thanks everyone for the help- I did discover the problem- when I re-hooked up the wires, I inadvertently connected both wires from the transformer directly to the button, without a leg to the chime (the wires from the chime were buried under insulation, so I originally thought they must be in the wall). When I re-routed the wires, it worked!
> 
> Thanks again- you totally helped me figure it out


Glad it worked out for you.


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