I came home today and I noticed my doorbell light was not lit. I pressed th e button- nothing. I unhooked the button, touched them together, nothing. I am hoping it is just the transformer. I need to borrow a volt meter- but I notice the transformer is warm to the touch. If transformer is bad, would it be warm?
The primary (120 volt) side is ok. The secondary (24 volt) side is bad. MAYBE.
A shorted secondary would make it quite warm. An unloaded transformer or one with an open secondary will be slightly warm. A partly shorted primary would also be quite warm - so warm or not warm really doesn't tell you much.
Right now I have the button completely unhooked
Go to Walmart and buy a voltmeter for around $10. It's not a big expense and they are handy to own for all home and auto repairs. Then test the output of that transformer, by putting the red test lead on one screw, the black one on the other. Be sure meter is set to AC Volts and any voltage higher than 25 volts, (probably 50V). You should read about 24 volts.
If there is no voltage the transformer is bad. If there is voltage, there must be a broken or shorted wire somewhere. If you have a basement, the wire (usually red and white) run across the basement ceiling. Maybe a mouse chewed the wire, or it was disturbed in another way. Or there is a bad connection. Sometimes those wires break right behind the button next to your door. The insulation may be intact, but the wire inside broke. You can usually feel a broken wire by jiggling them.
One other thing, if there is no voltage at the transformer, or it's very low, a short may exist in the wiring, so remove one of the wires from the transformer, and test again. If you have 24 volts after removing a wire, you have a short somewhere.
Doorbell wiring is pretty simple and it's safe to work on it with the power on. (except the 120 volt primary side of the transformer).
By the way, for auto testing, you set the meter to DC, not AC. Car batteries are 12volts DC.
You can buy/get a voltmeter for nothing/free except the cost of a purchase of some other merchandise using a Harbor Freight coupon. A $0.99 purchase is all it takes.
I got one of them. The first time I used it the end fell off one of the test leads, and could not be repaired because it's molded on. I had other test leads and got them. I think I used it three times before it completely failed on all settings. It helped fill a landfill along with all the other Harbor Freight garbage I once bought. The best thing to do at a Harbor Freight store is to drive on by, and go to another store. Harbor Freight does not sell tools, they sell GARBAGE!
Sure the transformer could be bad but if you are using a lighted push button. the light will go out id there is not a completed circuit /any where/ so your doorbell itself could be bad.
I'd first check all the wires, it could be as simple as a loose wire on the chime iteslf
My doorbell transformer is marked 16V, but it's actually about 18V.
of some other merchandise using a Harbor Freight coupon. A $0.99 purchase is all it takes.
Just got a nice Centech red multimeter from HF for free about three weeks ago. Even tests AAs and 9V batteries under load! Lasted until yesterday when the click detent mechanism no longer made "clean stops." Goes back next week! A little sphere smaller than a BB popped out of the case when I opened it but no clear sense of where it came from. I think I'll go for the free measuring tape next time.
Lots of stuff from them works well (my SDS hammer drill and recip saws work well every time I use them. Propane weed torch with igniter has seen three seasons without a problem. I got hosed buying hose clamps, though. Cheap zinc plated units and not the stainless steel that I thought I was buying. Operator error unless the ad said SS (it might have). De minimus. Retractable air hose for $39 was unbeatable, price-wise. Performs well and the hose is truly heavy duty.
Some people can mess up a hammer.
I have several of them and they are ok. I also have a couple of the Fluke meters that are a couple of hundred bucks each to compair them with.
Many of the inexpensive transformers will put out a slightly higher voltage unloaded then they will when under a load. For most of the simple door bells the voltage is not that critical.
If it 'works' like a carburator or lock cylinder, look for a little spring dangling loose. The BB goes on the end of it. Now push the BB & spring back into the hole they both came out of, and sit there trying to figure out how to get your finger out of the way before closing everything up again.
Eventually, you will realize that the time you have already spent doing so is worth more than the cost of buying a new unit.
I have a costly Fluke meter for electronic repair, I have a GC meter from Walmart that cost around $10, and is for basic home and auto wiring. I also have an old cheapie analog Radio Shack meter I have owned for around 40 years that still works fine. I also have a Heathkit VTVM from the late 50s or early 60s. Which also works well.
I wont own another Harbor Freight meter, even if it's free. I stopped going to their stores 3 or 4 years ago. That way, all you guys who are in love with their crap will get more of their Chinese garbage to add to the landfills. Besides Home Depot, Menards, Ace Hdw, True Value, and Sears, I recently discovered Northern Tools. That have a wide selection of darn near anything tool related, and their stuff is decent quality, for a fair price.
I think some bell transformers are 16V. Thermostat ones are usually 24. Either should work, but it's best to get the one it calls for on the bell unit, or you may damage the bell. Most read a little high on meters, just like car batteries usually read 13.5 to 14V.
Chris-
"Warm" is relative. Many transformers are designed so they run warm with no load. You should be able to hold your hand on it without screaming!
Some doorbell transformers have screw terminals on the low voltage secondary side. If yours does, disconnect one wire and reconnect it. If the doorbell rings, then the wires to the button are shorted.
Fred
Likely closer to 16 when the load of the bell is applied.
Does the doorbell ring? If yes, culprit is the little bulb in the button.
I have an inexpensive Radio Shack digital that is small and convenient to grab.
Any time the results seem a little strange I grab the Simpson 260 to verify. It's a bit clunky digging it out and untangling the probes but it doesn't seem to get phantom readings like the RS does sometimes.
When I was working in a large plant, I most often used my Simpson 260. With all the wires running in conduit together it was very easy to pick up the phantom voltage with the digital meters. Even the Simpson would often read about 60 to 70 volts AC on lines that were not active instead of the zero or 120 volts that is suspose to be on the lines when hot.
I found that if I wold start with the mete on the 500 volt scale and click it down to the lower voltage scales the meter would stay in the same or nearly the same physical position if it was the induced voltage.
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