Help with thermal fuse specs?

On Sun, 14 Dec 2003 23:09:53 -0800, DaveC wrote (in message ):

Of course, this should say "infinite continuity."

Of course, it should REALLY say "infinite resistance" or "no continuity".

ARM ;-)

On Mon, 15 Dec 2003 9:22:46 -0800, Alan McClure wrote (in message ):

Blast and damn those early-morn posts!

It certainly sounds like a 115C thermal fuse, but all the ones I've ever seen were cylindrical, about the size of a 3A diode, but with a metal shell and axial leads. One lead insulated.

I used to be able to buy replacements at Radio Shack, but I believe NTE sells a wider assortment.

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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On Mon, 15 Dec 2003 20:14:50 -0800, Jim Adney wrote (in message ):

Yeah, I got an NTE replacement. It is larger, and cylindrical, as you say. But there was room, and after ruining one by soldering it in without using a heat sink (Doh!!), I successfully installed one. Works fine, now.

Thanks,

BTDT

Isn't it amazing how quickly they respond to temperature? ;-)

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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Short the "thermal" fuse and wire in a conventional one. These fail because of repeated transformer currents on switch on. Use an appopriate value fuse.

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GPG: Not really a good plan...... .......a conventional fuse will not provide over-temperature protection and fire hazard prevention. The thermal cut-out fails not because of "repeated transformer currents on switch on" but rather because of over-temperature due to the windings in the transformer over-heating. Usually the thermal cut-outs, in addition to the temperature rating, have a CURRENT rating well in excess of the transformer application..... 2 amps for the small thermal cut-outs and 10 amps for the "common" ones available from Radio Shack, NTE, ECG, etc.

Exactly how will this protect the winding against over-temperature conditions? What is an "appropriate value"? Have you run the UL temperature tests to confirm the effectiveness of your recommendation? Modifications such as this are not a good idea.

Ben Miller