2

I am repairing a lamp whose plastic rotary knob has degraded and broken (as seen on the right of the photo below). The knob originally moved a small metal pin, which conducted the electricity for the lamp (the pin is visible in the center of the image on the left, and the top of the image on the right).

Two pictures, the one on the left showing the back of the fixture that holds the bulb, in the center of which is a movable metal pin.  The picture on the right shows the broken pieces of the plastic rotary knob.

Now that the knob is broken, it can't hold the pin in place. This has happened before and I've just glued the plastic back together, but now I'd like a longer term solution. Since I can't find a replacement for the plastic knob, I have inserted a cord switch into the wire instead, which works just fine. But to make this solution work, I need to keep the metal pin in place and in the on position.

Here are some options I've considered:

  • Solder (risking damage to the plastic bulb fitting)
  • Non-conductive putty (couldn't find something that fit the bill)
  • Glue
  • Cardboard
  • Rubber band

I've seen some posts online that suggest glue, cardboard, or rubber bands would work for low voltages (the latter two would be used to wedge the pin in place). But I don't know if 120 volts counts as "low voltage" for this purpose. So I'd appreciate any advice on whether one of these solutions or another one I haven't thought of would be most appropriate.

  • 4
    Can you post some pictures so we can see what you're dealing with? Is the knob repairable or reproducible? BTW, "low voltage" applies to the output of a wall wart (typically less than about 20v and low current). 120v is high voltage and you need a fix that meets code to avoid risk of popping breakers, starting a fire, getting shocked, etc. If the lamp is 120v, the design was likely certified by UL or some other certifying organization, so be careful about redesigning "outside the box". – fixer1234 Sep 19 '18 at 5:01
  • 4
    I am in agreement that a picture of the broken switch section of this lamp is the next step for this question. It is for sure that you do not want some dicey fix for this because of the high safety risk. Sometimes full replacement is the right answer. – Michael Karas Sep 19 '18 at 9:12
  • 1
    Thanks for the comments! I couldn't find a replacement for the knob, and I've already inserted a cord switch into the wire. I've added a picture to show the issue more clearly. – ASGM Sep 19 '18 at 14:32
  • I might try high temp RTV once dry it is not conductive I used to seal fly back transformers in old CRT tv sets many years ago. – Ed Beal Sep 19 '18 at 15:33
  • you can replace the whole socket with one you pull from a junk lamp. solder would be my first choice to fix it, the "plastic" should be able to take the temp for long enough to bond the metal, and a slight deforming of such a non-moving part won't hurt anything anyway. – dandavis Sep 19 '18 at 18:31
3

It looks like that pin is the internal mechanism of what used to be a switch that was integral to the socket. There is no a way to safely hold that in place. You are likely to get a high resistance connection or arcing, either of which will eventually destroy the lamp, and could cause a fire in the process. It generally isn't worth the effort and risk to attempt a home repair/redesign.

Replace the socket. It looks a lot like this one:

enter image description here

You can find replacement sockets of pretty much every type, including ones with integral switches of different configurations. This one I linked to at Amazon ($3.28 with free shipping as part of a larger order), but it may also be at your local Home Depot, Lowes, or electrical or lighting supply store. Or you can redesign the lamp using components that are certified by UL or another organization.

But repair it by replacing whole components that are designed to be used intact. The components aren't generally repairable. If you can't find the exact replacement, modify the brackets or other mechanical parts that hold the socket in place rather than trying to modify the electrical components, themselves. Hardware store have a big selection of brackets and parts you can use to make things fit an existing fixture.

The black and white wires in the lamp have crimped terminals that look like they may be salvageable to simplify connecting to the screw terminals on the replacement socket. You might need a Dremel tool to free them. If it's too much effort, just snip the wire behind the crimps, pull a little more into the fixture, and make new connections.

  • Sometimes the right answer isn't the answer you wanted - but I appreciate it nonetheless! – ASGM Sep 21 '18 at 17:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.