Every old home needs maintenance. Actually, every home does. It seems, though, that older ones are a bit trickier to keep up, for reasons like lack of identical replacement parts, inaccessibility, and modifications made over the years. Often, too, user manuals have long been lost.
This month I’m tackling a doorbell that sometimes works well and sometimes doesn’t. I don’t think many of you reading this will have the same doorbell mechanism. In fact, I doubt if any of you will. I write this only to encourage you to tackle things like this with a little less trepidation. Many problems can be solved by studying how something works and then making any corrections needed to keep things working properly.
Doorbells are usually grouped into two categories. Those which “buzz” or play music are usually newer and are electronic. The other type is much more mechanical, relying on moving parts such as hammers and chimes. Mine is the second type. Here’s a picture:
The painted wooden cover is not original, but is something I made about 40 years ago to replace the unrepairable plastic (Bakelite?) cover that was there. The pull cord on the left controls a small bulb that lights up under the cover.
With the cover removed, you can clearly see the attachment points of the tubular chimes. (You can also see the bulb mentioned above.) The circular mechanism on the right side is where the action begins when the doorbell button is depressed. There is a two-layer “arm” on that dial which begins to rotate counterclockwise. The outer layer maintains electrical and physical contact with a copper rim that goes nearly the whole way around the dial. The inner part of that arm touches each of the copper “bumps” during that rotation, and each bump produces a sound. When the outer layer reaches the gap in the dial, the contact is broken and everything stops.
Here’s a bit more detail on the chime tube mounts. Clearly, the loop allows the tube to hang in place, and the knurled nut permits in-out adjustments. Tiny “hammers” poke out of each hole behind the tubes, striking the tubes at the appropriate time to generate the chime.
It was hard to get a clear picture of a hammer as it poked out, but here’s the best I could do (with the tube removed.)
Opening the unit further, you can see that the hammers are flung outward by an electromagnet, and are anchored and returned via a small spring wrapped around each one.
The wire-nutted connection, by the way, is also not original. Many years ago I added a shut-off switch to disable the doorbell in case it was operated while my then-infant children were napping. This doorbell is very loud. (You may have noticed the sliding button on the right in the 2nd-from-top picture in this article. It apparently controls the voltage sent to the electromagnets, and consequently their strength. Having the hammers slap with less strength makes the sound less intense and quieter, but that’s still not as handy as having a shut-off switch during nap time!)
My plan was to give the hammer tubes a light wipe with a high-grade machine oil, thinking it would allow the hammers to slip in and out of their respective holes with less resistance. However, this tag is on the very top of the mechanism body:
Since oiling was specifically noted as the wrong thing to do, I reasoned that cleaning the tubes would be my best option. For that, I used a product that I really like for tasks such as this – automotive brake cleaner. It’s very volatile, meaning that after spraying, it evaporates quickly and easily. It is great at dissolving all types of “gunk” and isn’t expensive. Here’s a picture of what I used. Remember, I do not endorse any particular brand of product, and there are many brands of brake cleaner. This just happens to be the type I had on hand:
I’m sure it would not do any damage by shooting a spray directly into each hole, but I chose to spray onto a cotton swab (like a “Q-tip”) and quickly run the swab into each hammer hole. I then put it all back together and am pleased with the improved performance!
Again, you likely won’t have this same issue, but you might be able to save an old appliance or fixture rather than replacing it with a new one by taking the time to understand how things work. Gee, if it didn’t work before you tore into it, what do you have to lose by trying to repair it? Many old items were built with quality materials and are far superior to the mass-produced imported junk we buy today.
One final thought, though. Obviously, the above repair involved working where there was electric current. Doorbells usually have a transformer, probably remotely mounted, that steps down the voltage to the unit. Nevertheless, if you’re uncomfortable working around electrical current, then don’t do it. Rescuing your old doorbell or whatever you’re working on is not as important as preventing your electrocution or an electrical fire. Be safe!
I hope all your projects go well. Thanks for reading, and happy restoring!
Ed
If you’d like to download a PDF of this “Ideas” column, click here: