IE#8: Inside an old mechanical microwave timer switch.
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- เผยแพร่เมื่อ 21 ส.ค. 2016
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In this episode of Inside Electronics, lets take a look at an old mechanical timer switch that I salvaged from an old microwave oven. THE AUDIO AND LIGHTING IS NOT SO GOOD IN THIS VIDEO. BUT I WILL TRY TO UPGRADE THE QUALITY SOON WHEN I MAKE MY BUDGET. :) - วิทยาศาสตร์และเทคโนโลยี
More info about the timer :
6:16 The main rotary gear (the biggest one) contains some grooves that move an arm closer to the center once you set the timer past a certain point. This arm act on some gears and it change the overall speed. This allow timer have a non linear timing (eg: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 15 - 20 - 25 - 30 - 35)
As others said the gear which is outside the unit is to control power (watts) and make microwave turn on/off faster or slower, using some cams.
Thank you for your explanation. 😊🙏🏼
Nice. So when it comes to the 'temperature' setting, it's more often called 'power setting'. It doesn't know anything about the temperature of the food, that dial just decides how much energy is put into heating it.
The thing is, the magnetron that generates the microwaves can only be on or off, it can't be 'partly on', so the way they do that is, the timer unit switches the magnetron on and off every certain number seconds. So if you have it to 'half power', it will just turn it on for ten seconds, off for ten, and so on so it's only on half the time. Those bottom contacts must be the switch that controls that. When the timer is set, the top switch is closed which turns on the light, the fan, rotates the plate etc, and then that second switch controls whether the actual heating system is on.
Thanks, I forgot about that power part (because I have used it just a couple of times) and I thought the timer seemed needlessly complicated. I thought the TH-camr had mixed up timer and power. This explains it all.
@Robert Miles Thank you for the better explanation. 😀
@ Username Password 😀
I dint find what I was looking for, but your video helped me to figure out how this works and to find my own solution for my very specific problem. Big THANKS!
Thank you so much for your valuable feedback. :)
Thanks for opening up this. Seems quite rugged and is all mechanical! And that bell too. That other comment from Robert Miles clarified the power level part. Very interesting.
Thank you for your valuable feedback. :)
Excellent desctiptitive vedio. I liked you word selection and way of talking. Very nice english. Impressive & appreciable.👌
Thanks for your valuable feedback. :)
Yes brother/friend
Thank you mate. I had to repair one of those and hand no clue how it should look
Thank you for your valuable feedback. 😊
Thank you very much
The timer of my old microwave gets stuck sometimes in certain positions, the knob feels hard to turn, probably because dirt is stuck somewhere. Do you think it's fixable by little disassembly and cleaning without opening the gearbox, or does the resistance come from a gunked up gearbox?
If it's some solid particle or gunk, you can get it fixed by opening it carefully and giving it a proper cleaning. Sometimes it can be a chewed up gear wheel or a clogged motor. If so, it's a bit tricky and you better take it to a service center at this stage. 😊
Don't these usually work with a torsion spring?
Can you turn these back to 0? (is there some sort of clutch?)
This specific model uses a synchronous motor rather than a torsion spring. I'm not sure about other varients. Yes you can force it to zero.
@@INSIDEELECTRONICS We took apart our problematic Oven timer yesterday and it was a torsion spring based. (so is the new one)
I guess there should be no ill effects of forcing these counterclockwise, as from what I've seen inside the mechanism it doesn't spin the entire mechanism super fast but the main shaft just slips and the spring is reset to its resting state.
My father always says that it ruins the mechanism, while my POV was always that "it shouldn't". Even though I'm a mechanical engineer my father is vastly more experienced with mechanical stuff so I assumed he might have known something that I don't
If there is some sort of clutch mechanism, then perhaps it won't create any issues when forced to zero. But since I'm not familiar with such a type of item, I cannot confirm it. 😀 Always look for clues before forcing it hard, like whether the slip is rough or smooth, whether it makes any sounds that it shouldn't make etc.. Unfortunately without seeing one in person, I am really sorry to say, I can't help you in this.. 😃👍🏼
i have same , pl show running condition .
Sorry, this item was faulty to begin with. And I no longer hold this thing. So unfortunately I cannot make a second video for this item. :(
What is the resistance of a good motor? I measured 19k ohms on a broken microwave.
19k is a bit too much for a motor. You can calculate the approximate resistance by checking the wattage, from which you can calculate the current and hence the approximate ohmic value.
What is the electrical connection of the timer?Unfortunately i removed the connection.
Unfortunately the connection diagram varies from different manufacturers. And I don't have the unit with me to tell you the connection of this model also.
Damn. Yours is slightly different. The primary program contact switching plastic wheel is simply putted on that spring. Its from two parts. Larger wheel Down and small upper wheel which is seen inside the hole before dissasembling that goddamned mechanism. There is obviously something wrong
😶
I got IT! Its working. IT Just took 4 days.haha
LoL! Glad it worked! ✌🏽😀