I'm trying to obtain a thermal fuse to replace a blown one in a heated throw controller. I've added some images below. I can get a one which has a larger diameter, but I don't know if the replacement needs to be exactly the same diameter, it's squeezed between two resistors and I'm not certain if it's ok to have a larger diameter one that sits above the resistors. I'm trying to avoid throwing out a heated throw which may be otherwise ok. Obviously if another fuse blows the thing is goosed! Thanks.

 

hi jd,
This is the spec on that component.

E
The 12y umi is a thermal fuse that is part of the Elcut Umi Microtemp range of fuses. These fuses are designed for a variety of electrical needs, including 250VAC, 125VAC, and 50VDC. They are suitable for a range of appliances, from home to industrial.
E

https://www.google.com/search?client=firefox-b-d&q=12y+umi

Clip:
Here are some features of the 12y umi thermal fuse:

• High breaking capacity: Made from a robust alloy, these fuses are designed to offer reliable protection.
• CSA certified: These fuses meet rigorous safety standards.
• Versatile: These fuses are available in a 5-piece pack and can be tailored to specific requirements.
  

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Thermal fuses are safety devices that disconnect the current to the heating element if a malfunction occurs. This prevents the temperature from rising to dangerous levels, which could potentially start a fire.

 

Thanks for the info Eric. The google link in there is pretty much what I could find, I don't seem to be able to get a replacement of the same size, so do you know if I a fuse which sits above those two resistors would be safe? I'm guessing it would be ok but I need to be sure.

 

Hi j,
I would try tacking a 2A fuse across the dead thermal fuse, use a slow blow 20mm Fuse.
If it blows, you have a short on the PCB.
E

 

----> https://www.aliexpress.us/w/wholesale-thermal-fuses.html?spm=a2g0o.home.search.0

----> https://www.ebay.com/sch/i.html?_fr...+fuses&_sacat=0&_odkw=thermal+fused&_osacat=0

 

Hi j,
I would try tacking a 2A fuse across the dead thermal fuse, use a slow blow 20mm Fuse.
If it blows, you have a short on the PCB.
E

When I had a blown fuse (glass fuse, not a fusible link (a.k.a. thermal fuse)) I chased after a short circuit in a stereo amplifier. Naturally the first thing I did was replace the 7A fuse with another. It instantaneously blew. So I took an old incandescent light bulb (120V 30W) and using the two metal ends of the dead fuse I soldered wires to the bulb and powered the unit. The light bulb glowed. So I was then able to follow the circuit to find where the problem might be. Turned out it was a shorted bridge rectifier. So I replaced the BR with a higher amperage BR, powered the amp again and this time the lamp did not light. So I put another 7A fuse in the holder and the stereo is working to this day.

That was back when Radio Shack was closing most of their stores. I bought this amp at a discount of 80%. Don't recall the price, but for a 250 watt stereo PA amplifier, the price couldn't be beat. Also bought two very big and loud speakers. Used to play the drums and none of the stereo's I had back then could keep up with the volume of the drums.

Sold the drums. My Tinnitus has only gotten worse. Played rock & roll drums for 8 years as a teen and young adult. Played them again for a year many years later. Sold them to a young kid. Gave him some advice. Told him "I'm going to give you some advice. if you take it you'll probably never thank me. But if you don't - you'll wish you did. Protect your hearing." I remember the look on his mother's face. And I was choking up when I was surrendering my drums. I still miss the hell out of them.

Back on topic now - I replaced a fusible link in a washing machine. The company wanted $400 to repair the machine. I fixed it for $1.98 plus tax. Radio Shack again. AND the link I chose was rated for 146% normal operation. The original FL was rated for 101% normal operation. That's why you always build in some headroom. To my knowledge THAT machine is also still working.

 

Oh, forgot - - - Thermal Fuses can be blown out by a hot soldering iron. When replacing your FL use a heat sink that clips onto the lead, LIKE THIS; then solder it as quickly as possible. Don't linger with the iron. Looking at the pictures I would guess the board passed up a wave soldering machine at a fast pace. Solder did not flow up through the through holes, so it was either quick soldered or someone skilled placed the component by hand.

The washing machine? I blew the first FL by trying to solder it in place. Learned from experience.

 

Thanks everyone, some good tips there.

 

I have replaced several of those failed fuses with a jumper wire and never had any resulting problems. Especially the ones hidden inside cheap transformers, which seem to fail just after the warranty ends. Of course you do need to install a properly sized regular current triggered fuse or breaker in case there is an actual failure.