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Let's pretend your toaster need a little fix. Pulling the lever down, it does not stay low and immediately jump to its rest position. Apart from this, manually keeping the lever down, toasts your bread as usual.

This is a very common failure on toasters. One putative fix is to open the toaster and search for the system responsible for the lever lock. It consists of a coil with ferrite core on the body of the toaster and an other ferromagnetic (or magnetic?) element on the lever.

The fix consists of cleaning both pieces. It is really surprising how this fixes many of the toasters with similar issues.

I am familiar with magnetism, ferromagnetism and so, but I don't really understand how cleaning both sides helps in the process. Does the two parts need to have a good contact? For electric contacts it would help, but for magnetic contact, do you need a good contact?

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  • \$\begingroup\$ Possibly the pieces touch each other and complete a circuit \$\endgroup\$
    – Criticizing Israel not allowed
    Commented Feb 12, 2023 at 15:09
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    \$\begingroup\$ It's a magnetic circuit. If there is crud in the gap, the magnetic force is drastically reduced. \$\endgroup\$
    – Dave Tweed
    Commented Feb 12, 2023 at 15:26
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    \$\begingroup\$ probably nothing to do with magnetism ... most likely to do with reduced motion range of a mechanical component ... the crud prevents a mechanical component from engaging with another mechanical componrnt \$\endgroup\$
    – jsotola
    Commented Feb 12, 2023 at 17:52
  • \$\begingroup\$ @DaveTweed Do you mean that the crud introduces some distance upon which magnetic field lowers ? \$\endgroup\$
    – InfiniteLooper
    Commented Feb 12, 2023 at 20:32
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    \$\begingroup\$ @Jasen Nani ??? \$\endgroup\$
    – InfiniteLooper
    Commented Feb 13, 2023 at 8:32

3 Answers 3

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It's an electromagnet that holds the arm down, I would first suspect the tap on the heating element that produces the low voltage that runs the timer and the electromagnet. This is usually just a riveted connection and the voltage is so low that were it to oxidize it would stop working. Just poking it is probably enough to get it working again.

Cleaning the electromagnet or armature seems unlikely to make a significant difference unless there is a thick layer of crud there, or the layer contains magnetic material. Probably during cleaning the low voltage tap will get disturbed enough to revive the toaster.

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The system that holds the handle in the down position is nothing more than a spring-loaded catch. If that is dirty, it may stick in the unlocked position, and the catch may fail to operate.

Pushing the handle down also turns on power to the heating element. A bimetallic strip near to the element gradially warms up and bends. When it has bent sufficiently far, it operates a contact, which turns on an electromagnet. The electromagnet pulls the catch open, releasing the handle. As the handle springs back up, the toaster is turned off.

Another problem that these toasters may have is that they buzz loudly at the end of a toasting cycle, but do not pop up the toast. Again, that's a sticking mechanism, where the electromagnet can't pull hard enough to release the catch.

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    \$\begingroup\$ That's a different system than the one in the question. What they're referring to is one where when you press the lever down it activates a timer that turns on the electromagnet, this holds the lever down until the timer times out and releases it. These won't latch down at all if they're not plugged in. \$\endgroup\$
    – GodJihyo
    Commented Feb 12, 2023 at 19:51
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As others mentioned, the crud won't make much difference in terms of magnetic attraction unless the layer of it is very thick.

However, in many toasters, the same lever makes contact with the core of the coil and closes the circuit, latching the electromagnet on. So, electrical contact is also necessary, and it can be disrupted with even a slight amount of debris or oxidation.

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  • \$\begingroup\$ The system closes somewhere else. Keeping the lever down usually makes the toaster toasts. So the system usually closes by the action of lowering the lever. \$\endgroup\$
    – InfiniteLooper
    Commented Feb 13, 2023 at 10:35
  • \$\begingroup\$ @InfiniteLooper is there a specific example where the circuit closes in a place other than the core, yet cleaning the core fixes the problem? \$\endgroup\$
    – Anton
    Commented Feb 14, 2023 at 15:39
  • \$\begingroup\$ Yes, the case presented in other answers \$\endgroup\$
    – InfiniteLooper
    Commented Feb 14, 2023 at 16:18
  • \$\begingroup\$ Are you sure that's the case? Simon B's answer presents a system that does not rely on an electromagnet to hold the lever down (the answer is correct in that the catch could be stuck in the unlocked position, but that wouldn't be fixed by cleaning the electromagent core and lever, but rather the catch mechanism). Jasen's answer does not specify where the circuit closes. \$\endgroup\$
    – Anton
    Commented Feb 15, 2023 at 16:25
  • \$\begingroup\$ Usually the system closes using a king of interrupt, providing 230VAC to the resistance of the toaster. Then you have a voltage divider and a diode to get low DC voltage for the electromagnet. \$\endgroup\$
    – InfiniteLooper
    Commented Feb 15, 2023 at 17:18

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