Was It Thermostat That Rendered Toaster's Locking Mechanism Inoperable? - Page 1
Forum section: electronics / general

author: Boris_yo
author_rank: Frequent Contributor
timestamp: November 03, 2012, 06:26:49 pm
content: I have thisMoulinextoaster for more than 5 years now and while handling with care, yesterday noticed that it no longer locks while it is conneced to mains and when slices of bread are inside. See video below:There is however a less convenient and unsafe way to operate it which is either standing near and keeping lever pressed or putting something heavy on lever backed by near object to hold it, the way which is of course unsafe because you are free to leave and do other tasks while leaving toaster unattended (which frankly was what I did today and forgot to set timer, only to come back and see smoking toaster with burned bread inside).The toaster is still in good condition and nothing happened to it, but I wonder if I should remove plastic casing and determine what is obstructing mechanism from locking down, given it is mechanical problem. In case it is thermostat, I take it I should trash toaster and buy a new one? Wonder though whether to buy one with 2 cells or 4 cells...

author: SeanB
author_rank: Super Contributor
timestamp: November 03, 2012, 06:37:39 pm
content: Buy a new one........ Most common fault is built in, in that there is a hold down contact which is kept closed by an electromagnet, and the cheap thin plastic it is moulded from breaks from time and use, not allowing the electromagnet to hold the latch. If it has a button you press to release the toast it is this kind of mechanism.The older ones used a metal pawl and latch, which wears round and no longer latches on the bimetal spring. That is fixable with a bit of filing.

author: IanB
author_rank: Super Contributor
timestamp: November 03, 2012, 06:42:22 pm
content: It could be something simple like a breadcrumb obstructing the mechanism.I would unplug it and give it a good shake upside down and all around to give it good cleaning and empty all the crumbs out of it. Maybe even take the plastic cover off to help get the crumbs out of the hidden corners.

author: tom66
author_rank: Super Contributor
timestamp: November 03, 2012, 07:02:43 pm
content: Yeah, it's quite a clever but potentially dangerous mechanism.When you pressed the carriage down a circuit is created which powers the timer and heater, which immediately energises the coil.When the timer is up the coil stops, lever pops up, breaks the circuit to the heater.Spotted the problem? If anything jams the lever down, the heater will continue to operate, potentially leading to a fire hazard.Anyway the problem is likely on the timer. It is usually electronic in design, a small PCB with a timer IC. Surprisingly, I have never seen one with a 555 — always a custom IC I couldn't get a datasheet on. (I would have thought the 555 would be cheaper.)

author: IanB
author_rank: Super Contributor
timestamp: November 03, 2012, 09:35:26 pm
content: Yes, it could be an electronic failure, but first eliminate the simplest causes. If any foreign object gets in between the electromagnet and the magnetic plate it will keep them apart and the magnet won't stick. I've seen many electronic toasters where the lever wouldn't stay down when pressed and they have all been fixed by a good shake and a bit of percussive maintenance.Now if that isn't the problem then sure it's something else, but in my experience mechanical problems are more common than electronic problems. Most electronics are very reliable.

author: Boris_yo
author_rank: Frequent Contributor
timestamp: November 05, 2012, 06:49:03 pm
content: Quote from: IanB on November 03, 2012, 09:35:26 pmThank youIanB! Before reading your reply, I've casually solved the problem and I don't know exactly how because I didn't resolve to percussive maintenance. I just placed bottle like I did in a last few days and when released it from lever, it remained pushed down. I thought I've really broke it now because it stuck when it was time to take bread out... So I rushed to unplug toaster from mains but to my surprise when I started making toasts afterwards the lever stayed put and released itself when it was about time which means timer is okay!I am wondering however if the problem is actually solved and no longer exists risk of mechanism failing again... Just want to be safe so though I have already used toaster several times, I still should exercise awareness.