Hey Ian...
Some soldering tools are not temperature regulated, and sometimes things just go bad. Weller soldering guns for example have no temperature control. They depend on the user to know when to stop pulling the trigger.
I have the unit pictured below. I dunno how it does it, but it certainly responds to the temperature dial. However, even with the "new" tip it seems to have a lot more hysteresis than I remember - Again, no idea why.....
I too have a Weller gun, but it doesn't get anywhere near this stuff! I've seen some *bad* results from folks overheating those things
The soldering station I have use two different systems. My older regulated pencils use a metal that loses its magnetic properties at a certain temp, and this releases a magnet that releases a switch. The tips are all stamped with a number for the degrees where they shut off.
S-w-e-e-t-!
Of course I have cheap irons that have no regulation at all, so they overheat and ruin tips if left on for extended periods of non-use. The only way to make tips last a long time with my unregulated irons is to unplug them.
Yep, given that this is (was!) the tiniest tip I've ever plugged in, I think I toasted it! I honestly didn't think that was possible (?), but it sure seems that way
Cheers,
Ian