Instructables
Picture of Taking Apart A Microwave
Taking apart a microwave. Fairly simple. Fairly dangerous if you just plugged it in to "See if it works" and then start taking it apart. 
it's also worth the very little effort. I've taken one apart to show you what you get.


PS: I'm only thirteen so don't be too critical
 
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Step 1: Things you should know

Picture of Things you should know
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there are a few things you should know before you start. 
1. Don't power up the magnetron. You will probably DIE
2. Don't use the transformer unless you know what you are doing
3. Be Safe
4.Take out any loose objects (the glass plate)
5. Have fun

The tools you will need are simple and everyone should have them. 
A screwdriver and a pair of wire cutters.
It helps to have a drill with a screwdriver bit.

Step 2: OK

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Alright! 
Enough Blabbering. Lets get started.

TIME TO CUT THE CORD!

Step 3: Remove the cover

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Remove the cover. This might be a little bit difficult but use common sense. Remove all  the screws golding it in place and lift up the cover like shown in the picture. it should snap right off.

Step 4: Lets have a look inside

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title says it all.Remember to unplug any connectors instead of snipping wires.

Step 5: The fan

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Take out the fan. Most parts in the microwave operate  on 120v AC (unless you live in a place that has 240v  AC like me)
This is good as a ventilation fan for the workshop of a cooling fan or something.  

Step 6: The Cap and diodes

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take out the high voltage capacitor and diodes. The Capacitor is worth a few dollars and the diodes are useful for other high voltage projects. 
the reason there are the diodes and capacitor in the microwave is because the magnetron  requires DC current to operate. These two components (cap. and diode) are used to convert the AC current from the transformer to DC.





Warning: DON'T USE THE CAPACITOR UNLESS YOU ARE QUALIFIED AND YOU HAVE LOTS OF ELECTRICAL EXPERIENCE
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Cube_4 months ago

Actually the diodes and capacitor are a voltage doubling rectifier circuit.

The magnatron operates not at 2.5Kv but at 5Kv. (1.25A 5Kv is an instant kill zap on that matter)

As for the rectifier circuit used it's probably a Greinacher rectifier (it's cheap and has good ripple characteristics, parts used: one capacitor and two diodes incidentally)

a quick google search provided this schematic
http://upload.wikimedia.org/wikipedia/en/thumb/1/1...
Mind you I feel somewhat obliged to mention that you REALLY shouldn't be playing with electric power in excess of 5Kv at any age.

mmoore526 months ago
Thank you. How do I discharge the components that might kill me lol?
I_StarkGuy6 months ago

A safe way to discharge the capacitor is to wear thick leather gloves and touch both terminal with a couple of wires connected to an incandescent bulb. Then you solder a BIG resistor across the terminals to keep the capacitor from recharging with static electricity.

3dcats9 months ago
Thanks for posting - excellent photos and explanation.
amclaussen1 year ago
It would be safer to discharge the capacitor with several 1 Kohm resistors. The tricky part is doing it without touching any part or using any thin insulation jumper cables, that WON'T insulate the very high voltage present! MANY sloppy working technicians have been killed when repairing Microwave ovens in many countries, The last one I have read about in the local newspaper was less than three months ago... go figure. The poor guy had several years of experience repairing TV's, Stereos and some Microwaves too, but he was electrocuted! Some Microwave oven capacitors now come with resistors placed between terminals, as to safely discharge their high voltage; but not all. Therefore it is mandatory to discharge them before proceeding further with disassembly. BTW, there are nice and tested Instructables for using the tranformer for a DIY arc welder, since the transformer has a favorable winding ratio when used backwards, that is, the secondary High voltage is used as the primary, and then it lowers the voltage but is capable of a sizeable current in the (now) low voltage side. Anyway, be extra careful and know what are you doing, never use both hands when servicing or playing with high voltages (keep one hand in your pocket, so that if by chance you touch a HV point, the resulting current won't cross your chest and in that way you are a little (just a little) safer. Use insulating material shoes over a completely dry floor or place a rubber mat, take off any wristwatch, neck chains, finger rings, metal belt buckle etc.
dog digger (author)  amclaussen1 year ago
Thanks for the great advice. I've though about re-winding the transformers secondary with 3 phase cable (10mm^2 I think) instead of flipping it, just so I don't burn out any windings
I thought microwaves only had one diode...
the magnetron itself is a diode(its a vacuum tube too) and yeah it rectifys the ac

those two diodes and the capacitor are arranged in a voltage doubler matter of fact
dog digger (author)  Jimmy Proton3 years ago
Well mine had two. For rectifying one "channel" you need two diodes. For the Live and Neutral you need four diodes. You probably know more about this than me.
Research Wheatstone Bridge

Basically, your mains freed is probably tapping one phase of a three-phase, sometimes four-phase, street feed against neutral (some soul at the far end of the street usually has all phases, and in Belgium they tap across phases, two lives, no neutral). That means live feeds fluctuate sinusoidally, usually both sides of zero. But you need a second rectification bridge for the negative side from the positive, and to bridge the two into a single output you need further capacitors ti buffer against the unwanted phase being tapped on the other circuit leaking into the output. The result is a loop of four diodes, negative to positive all the way around, input across connections 0 and 2, output across 1 and 3.
That simply flips the sine wave into a bumpy DC, as the trough becomes a peak alongside the existing peak. To smooth that out, a capacitor is used to flatten the peaks and troughs
there is a "giant" diode on the capacitor connected to ground, at least mine has it, i think it is for dischrging the capacitor when the microwave is off or something..
I believe the diode is to turn the AC current into half wave DC-correct me if I'm wrong.
dog digger (author)  Jimmy Proton3 years ago
The capacitor is for smoothing the voltage after it's rectified
dog digger (author)  Exiumind3 years ago
It's for Rectifying the AC voltage to DC for the magnetron to work.
hm yeah, since the magnetron uses negative voltage.. =)
cool instructable mate.
Microwaves are a lot more dangerous than you think to take apart. The capacitor can store a charge for a long time, so never assume it's completely discharged until you discharge it yourself. Furthermore, the capacitors charged carry around 200 joules of energy [1/2 x (Voltage squared) x capacitance in farads], it only takes 100 to restart your heart. Be careful with them. Without the transformer they are pretty much useless as they won't carry near enough energy to do anything, and they're AC capacitors so you can't use them for any coils? like you said.

Fans like in microwave ovens work through inductance of magnetic fields. A magnetic field surrounds the motor spindle which carries small magnets of alternating poles, causing the motor to spin (Wikipedia inductance motor, and AC motor for more on how it works). I have no idea what you're talking about with it drawing 70W because it uses a transformer and its far away from the actual motor. It does not use a transformer, it uses standard AC that the microwave plugs into and the motor is attached directly to the fan blades. The fan is inefficient and draws so much power because manufacturers of microwaves try to make the microwave as cheap as possible, which includes inefficient fans, bulky transformers, and cheap parts. Newer microwaves use more efficient transformers that require less power, and use more quality parts.

Microwave ovens use one 2000v diode to supply half wave dc to the magnetron (again, Wikipedia rectification)

Actually, the capacitor is mainly to double the voltage output of the transformer to 4000 volts dc, (half wave) rather than smoothing the voltage. The magnetron really doesn't care how consistent the voltage is.

The beryllium oxide is a carcinogen as in cancer causing. According to the state of California, wood dust is a carcinogen, as is everything else in that state. Anyway, it is not particularly harmful to the environment, so it's not a hazardous waste material.

Again, be careful, don't experiment with high voltages until you're older, so good job sticking with a 12v ac transformer rather than the 2kv MOT. Have fun!

dog digger (author)  tinstructable2 years ago
That's why I discharged the cap with an insulated screwdriver but I never got an arc because the microwave hadn't been used for 5+ years. Also, I said transformer (with the fan) and I should of said electromagnet. One question; would moving the electromagnet closer to the man motor assembly make it more efficient? Also, how does the cap double the voltage? I had 2 diodes in my microwave but that could differ from microwave to microwave. I think that the beryllium oxide (like asbestos) must be agitated to be effective as a carcinogen. Wood dust as a carcinogen? if it was treated wood, that would make sense.
Anyway thanks for the advice.
This is good, but I really need you to send me those parts for verification, so I can rate this instructable. Thanks :p
dog digger (author)  scraptopower3 years ago
What do you mean?
He's kidding about you sending him those parts to keep to "verify" so he has them to experiment with.
dog digger (author)  scraptopower3 years ago
tell me what you mean and what i have to do
Nothing, I was just joking about getting your parts for free :p
hbell3 years ago
I like the fan, I dont know much about it, but it works like a transformer I think, but draws around 70 watts which is a HUGE amount of power for a little airflow, but I use it all the time, comes in handy when cooling down cakes from the oven.
dog digger (author)  hbell3 years ago
I think it draws 70W because it uses a transformer and it's far away from the actual motor so it makes sense
Yep it works similarly to a transformer, but the actual assembly of the motor is inside the iron part, so it must use AC directly.
foobear3 years ago
It looks like the timer circuit has its own transformer, I wonder why?
dog digger (author)  foobear3 years ago
Probably to step-down the voltage for the LCD or the IC's or something.
yes because all the parts at at the timer circuit are from 1-6 volts max
dog digger (author)  morphic cu ion3 years ago
Actually I think it's 18 volts because thats what the relays require to operate
multiple secondary coils?
or from those 18v relays it uses transiistor to do the triggering (maybe a voltage divider for the ic circuitry)
Exiumind3 years ago
my transformer is rated 5Kv =p
on other microwave i have the tray wont spin, dont know if its simply a loose wire or something more sirious.. i cant take the cover out since the screws are kinda wierd.. =|
profpat3 years ago
great instructables, specially for recycling the parts!!!
dog digger (author)  profpat3 years ago
Thanks!
krk19483 years ago
Thought myself dissembling ! Thank you very much !
dog digger (author)  krk19483 years ago
Your welcome!
That was a good instructable! I used to take apart every single microwave, TV, stereo, VCR, DVD player I could get my hands on! Fun stuff!
It's great what you can do with the stuff you salvage!
dog digger (author)  EngineeringShock3 years ago
Thanks. Because I don't have tons of money to but the components with, I salvage them from broken equipment. Once I found an awesome audio power transformer from and old hifi amp left on the side of the road. You can also salvage parts that are hard to find and are only found specific things. Rear projection TVs are AWESOME. The panel is like a magnifying glass, you get some pretty decent speakers, the circuit boards have plenty of components and there are lots of flybacks!
Oh I totally agree. There is nothing more satisfying than salvaging something, and making it into something else. For free, no less.

I used to work at a Computer monitor company, and I always have a ton of flybacks to play with. Gave my self one hell of a shock once too =(

Anyhow, keep up the good work!
dog digger (author)  EngineeringShock3 years ago
Nothing better than working for a technology company. You get tons of awesome stuff! I'm to young to work now but nothing will hold me back!
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