Fixing a dehydrator

Our Nesco deyhydrator gets heavy use in the summer, drying fruits, vegetables and even complete meals for future use in winter or on camping trips. This simple device consists of a number of plastic mesh-bottomed trays that stack on top of a ventilated base. On top of the stack is a lid that contains a heating element and a fan.

This last summer, the deyhydrator suddenly stopped working in the middle of the night.

Nothing worked: the fan wasn’t spinning and the heater wasn’t heating. I took the lid apart and found that the circuitry was extremely simple, but there was one thing that looked unfamiliar: a device that looked like a metal-cased resistor, with label that said “SF129E”:

Web searching revealed this to be thermal fuse. To test if the fuse was the problem, I wired a temporary jumper around it, and the fan and heater came on again. So I bought a five-pack of replacement fuses on eBay (having spares seemed like a good idea). The fuses are also available at the nearly defunct Radio Shack, if their web site can be trusted.

The tricky part of replacing the fuse was avoiding the use of a soldering iron, because the heat could blow the fuse. The old fuse was wired in with crimped connectors that would have been nearly impossible to open without destroying them. So I clipped the old fuse as close to the metal body as I could, then wrapped the leads of the new fuse around the now-dangling leads of the old fuse. This hack kept the dehydrator working for the rest of a very busy harvest season.

Apparently, this kind of problem is common with other heating devices like hair dryers. I suspect many such devices get thrown away, when they could be fixed for a couple of bucks.