Home Repair: Door Bell Transformer

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Before I go set up an account on yet another forum (they are great though), I figured I'd see if the handy bunch here has any opinion on this.

My house was built about 6 years ago and at the beginning of the summer I noticed my door bell went dead when a delivery guy had to knock. I took a look and noticed the plunger for the bell mechanism was somewhat melted, and it couldn't move anymore. I chalked it up to cheap Chinese components and just switched the wire over to the other chime (theoretically for the back door). That worked for another couple months before it quit again. Same issue. Melted plunger. I happened to mention this to one of the guys at work and he told me about how he came home to find his door bell smoking one day. I came home and disconnected everything.

I figured the first place to look was the transformer. I checked it with the multimeter and it read about 5 volts. The unit was supposed to be 16v. Figure I might have found the problem.

So I just bought a new transformer and bell mechanism and just finished wiring it all up. It works, but when I checked the transformer voltage, I am getting a reading of 22v on a 16v unit.

I am admittedly a novice on this (as I am at just about everything "handy"), but I am wondering if this a problem. I had my doubts about these cheap Chinese transformers, but I couldn't find anything else online or in B&M stores. Do I have another bad transformer? Or are these kind of variances normal? Could there be another problem? I'm going to be cursing this home builder again if I need to call an electrician for a door bell in a 6 year old home. My parents have been in their home for 25 years and haven't had to replace door bell transformers. Thanks for the advice as always.
 
Hmm, I had a melted old one of these in a dumpy slum I rented fresh out of college. I figure the outside button got some corrosion and overheated it in the "engaged" position. When I unhooked the wires it finished its "dong" and acted very relieved.

Do you have a light in your doorbell button? I don't expect it makes much difference.

It can be normal to have an unloaded voltage that much over the rated, though I defer to someone who's done more work on doorbells.
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With your door bell button disconnected, check its ohms at where it connects to the rest of things. Should be infinity if unlit and close to it if lit.
 
Originally Posted By: VicVinegar
It works, but when I checked the transformer voltage, I am getting a reading of 22v on a 16v unit.

Just a guess, but I don't believe the exact voltage is that important to a product like a doorbell that sees momentary duty. They probably know this in manufacturing and have a wide tolerance on it.

And speaking of momentary duty, I agree with others that the doorbell was stuck in the ON position, and resulted in melting.
 
The higher the voltage the lower the amps. That is why it melted the button and read only 5v. It is indeed cheap transformers as long as all the wiring connections are well bonded.
 
Replace the switch. It has been sticking and that's what cooked your old doorbell.

If you measure the voltage with the button pressed it will likely read closer to 16 volts - it's not really a problem.
 
I don't have a button that lights up outside. The piece that melted was the plastic plunger that hits the bell inside the house. After the second one melted, I did take off the outside button and checked the connections to make sure it wasn't stuck "on". Everything looked fine.

I bought a whole door bell kit, so I have new buttons. Maybe I'll just put a new one on to be safe.

I did just read in a DIY forum that 21v unloaded is acceptable on one of these. So I am probably OK. I just want to be safe that is all, and judging from some of the other "craftmanship" around this house, I wouldn't be surprised if there was some shotty work.
 
Don't discount the doorbell button as the cause of the issue. Cheaply built switches that are exposed to the elements and outdoor temperature changes can do some strange things. A visual examination of the switch may not tell you what it's doing when the sun hits it for 8 hours.
 
I replaced the switch, hopefully everything is good to go.

I got "OL" which the Craftsman multimeter says is infinity when I checked resistance at the switch.
 
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Im glad Ive kept our 50+ year old switch when we were doing some exterior painting!
 
When you checked the voltage, are you sure the multimeter was set to read AC volts? If it was set for DC it would give an erroneous result.
 
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