A lamp in my living room that I have been using with a 3-way bulb (50-100-150) has developed a problem. Lately, it keeps burning out the 100-watt filament. I just put in a new bulb, and, sure enough, it immediately blew out the 100. The 50-watt filament is fine.
Any thoughts on how I can fix this lamp?
I can’t imagine anything external to the bulb that would cause this. Has it happened more than a couple of times? It might be just an extreme case of “infant mortality”; you might have gotten a bad batch of (cheap) bulbs.
Just had a second thought - perhaps the filament isn’t burning out. Instead, the bulb may not be making good contact with the 100w contact in the socket. Try tightening the bulb some more.
Perhaps you have a short circuit in your switch.
That would bypass the filament, resulting in nearly zero volts (and, therefore, zero current) through it. This would probably damage or destroy the switch, and certainly blow the circuit breaker, but it wouldn’t hurt the bulb one bit.
ETA: I think BJMoose’s second thought is likely close to the mark.
Or, after unplugging the lamp pry up a little on the bits of metal that make contact with the bulb.
Looking in my 3-way socket, the one that touches the ring doesn’t look very pryable, so it may be that the one contact has worn down. Then you’d need to replace the socket (which isn’t that hard).
Is the lamp brighter when you switch between the 50w and 150w setting? If it is the 100w portion is fine for sure. The highest setting is achieved by running both filaments at the same time.
You either have a bad socket connection or a bad switch I’d have to say. The filament for 100w would have to be factory defective to instantly blow out.
Low - Only the 50w filament goes on.
Medium - Only the 100w filament goes on.
High - The 50w and 100w filaments go on.
I highly recommend you purchase a bulb of different manufacture if the 100w filament is truly going bad. There is no way a bad switch will burn out the bulb instantly.
I think what befuddled me earlier was that I simply bought into your assumption that the filaments were indeed breaking. Do you have any way to test the questionable lamps? (Put 'em in another lamp, check 'em with an ohmmeter.) If they are indeed bad, it was probably a bad batch of bulbs. If they’re actually good, then it’s the socket or the switch. (Small chance it could be both, but you’d really have to piss off the gremlins for this to happen.)
Thanks to all. The filaments are indeed breaking (I can see them waving around inside). This happened with three different bulbs: the original that had been in there for some time, one cannibalized from another lamp, and a new one of different manufacture that was just purchased.
From what you all have said, it appears that I am cursed. My wife has never liked that lamp much anyway, so we’ll probably just retire it.
For what it’s worth, I have the same problem with three-way lamps and bulbs, although I find it just as likely to burn out the 50W filament. I’ve never been able to keep a bulb with both filaments intact more than just a few weeks.
Now I just buy one-way bulbs and use those, since that is what a three-way would turn into very soon anyway.