That sounds more like a "thermal protection switch" instead of a fusible link. https://www.thespruce.com/understanding-the-term-thermally-protected-on-an-electric-motor-1152872The sole purpose of the fusible link is to prevent fire.
Then after that description your talking about a thermal fuse. A fusible link is usually a short length of wire 3 gauges smaller than the circuit needs with a teflon insulation.The ones I've seen have been rectangular whereas the ones I most commonly see in motors such as fans looks more like a diode
They put those thermal fuses in any device that has the reasonable possibility of overheating and being a fire hazard. The better quality devices have better insulation on the wires and adequate iron and copper in the transformers and other magnetics. While some may defend using them, O hold that they are a substitute for adequate quality. Consider that a motor or transformer with such a devcie embedded in the windings is considered non-reparable, and that replacement transformers and motors are seldom available as repair parts. So one time overheat and your stereo box is scrap. But never before the warranty runs out. The concept being it is not worth repairing.While the mention of fan motor failure has come up - it isn't what the TS is seeking. I drew what I believe to be the switch diagram based on past experiences. Wherever a fusible link may be - or whether this switch has come from a failed fan - none of that matters. The topic of this thread has been help with a wiring diagram.
We haven't heard from the TS since post #1, so I'm assuming his question has been answered and he has no further interest in pursuing this thread. Either the question has been answered or he is unaware he's gotten any answers. Whatever.
Oh, and the fans I'm most commonly referring to are box fans (window fans). But have seen fusible links elsewhere as in post #10.
I have bypassed those thermal fuses on transformers and never had a failure afterwards. Often the device is burried just below the surface and the device leads are obvious and different from winding leads. In the case of the washer machine, since the case was riveted shut, it is clear that it was not intended to be repaired. And the service tech persons were either lazy, stupid, or dishonest, or a combination of those. So it seems that perhaps those "Factory Trained" service people may have been trained in a candy factory. I can tell about a fix on a computerized washer machine, where the service guy quoted a new computer board for about $450 installed. My reputation got me called in for a second opinion. I read the service instruction sheet, did a front-panel service reset, unplugged it for 5 minutes, plugged it back in and it worked just fine. 3 years since and still just fine. The charge for my 15 minute service call was outdone by my tip for the service call.@MisterBill2 in the case of my MIL's washing machine, she was ready to replace it. The machine was still quiet new; probably just out of warranty when the mode shift coil went dead. Overheated. Or more accurately, the fusible link blew. Service techs said they had to replace the entire mechanical unit at a cost of $333 to $400 US. Mom said she'd just get a new one. I said wait - let me mess with it.
The OBD said it was a bad Mode Shift Coil. So I unplugged the MSC and sure enough - it was open. It was held in place via two bolts, so it was easily removed. When bench tested, it was still dead. So I drilled out the rivets and opened the casing. The inside was pristine. No indications of heat anywhere. No nacrid smell. So I checked the FL (fusible link). Found the open. Looked up the specs on line and it turned out the rating for that FL was 104% of normal duty. Meaning it had no chance of surviving for long. I went to Radio Shack and bought a new FL for $1.98 plus tax (US) and crimped it in. Then put new rivets in the housing and reinstalled it. That was a good seven years ago and the machine is still functioning flawlessly. The FL I chose was one that came to a rating of 140% normal duty. So it was going to last. Yet, if there were an overheat condition - it would blow at 120˚C (248˚F). Though they're generally not user serviceable, someone who has even a minor level of talent can repair such a blown link.
In the case of fan motors, they're often buried, and replacing them is next to impossible. Given the cost of a new fan - why would anyone want to do all that work just to repair a fan that can be replaced for around 20 to 40 bucks? But a washing machine that costs over $500 (US), a $2 repair - - - priceless. Well, nearly priceless.
Those links are primarily there because of UL and other safety organizations that mandate them to make the consumer experience a safe one. I, too, have bypassed them with no harm. However, when you consider that a box fan (I know, I keep going back to that), when the bushings bind up and the fan sits there in the window with lace curtains and heavier fabric curtains - house fires are highly likely. That's the main reason for their existence.I have bypassed those thermal fuses on transformers and never had a failure afterwards.
I called GE and tried to get them to sell me the coil. They refused. Said I could buy the entire mechanical assembly (MSC included) for $135.00 (US). First, I didn't want to spend that much money just for a coil. Second, I didn't want to do all that work just changing the mechanics. I know I could have just swapped the MSC for the new one and NOT do all that work, but why spend all that money for a coil, who's sole job was to slide a locking collar over a spline to switch from agitate to spin? For the time and effort as well as the capital investment, a new machine would have been a far easier choice. More expensive, but easy.And the service tech persons were either lazy, stupid, or dishonest, or a combination of those.
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by Luke James