microwave oven control panel

[thor]

Hello!!!

I print t-shirts. I am using 3-20watt florescent bulbs/tubes to develop my silkscreen frames. Usually it takes a few seconds to a few minutes to develop the film, depending on the ambient temperature and humidity . For the past decades I just manually count my way or refer to a wall clock and manually turn on and off my light source. Ive been dreaming all this years to automate the task to make it more reliable, but I can not afford a timer with seconds and minutes settings that can be linked to my light circuit. Just this weekend a friend of mine discarded a Whirpool microwave oven that he told me can not cook beyond a few minutes setting.

Can I make use of its control panel to turn my light source instead. I have a Readers Digest How-to-Fix-Yourself Manual that shows the general parts of a microwave. But when I opened the microwave, I was overwhelmed with the amount of wires that go from the control to the magnetron to the door and to the transformer and vice-versa.

Can anyone help me figure this out.

Thanks.


Thor

 

[(*steve*)]

BE VERY CAREFUL

There is a capacitor in the microwave that can hold a charge easily large enough to kill you. And it stays charged for a LONG time.

If you can keep well clear of this (I advise keeping your left hand in your pocket the whole time the cover is off).

Generally speaking the timer is pretty simple, but there may be a bit of wiring to interlocks and other stuff.

 

[thor]

Thanks Steve. I'll put your advise in my head and my left hand in my pocket. Can you help me through the maze. My initial idea is to rid of the magnetron and transformer and hook my light instead to the panel. But which wire to pick and which to rid. Thanks again

 

[(*steve*)]

I can't see your microwave, so I really can't comment.

With pictures I *might* be able to say something, but it's really a case of tracing where the wiring goes. It shouldn't be too complex (famous last words)

 

[War_Spigot]

I've never worked with high voltages really, but would it be best to discharge the capacitor with a screwdriver or something? I always do when I'm taking things apart, but none of the capacitors have ever been charged(except for once in the flash cap in a camera)

 

[(*steve*)]

The voltage on that capacitor is high enough that you could get a nasty (even deadly) shock through your screwdriver.

I'm sure there are people who recommend safe ways to discharge them on the net, but I'm not going to recommend one at the moment. Google, see what you find and we can tell you what we think. One of the last stages should be fitting a shorting link across the capacitor -- if the instructions don't include that, then move on.

 

[War_Spigot]

The voltage on that capacitor is high enough that you could get a nasty (even deadly) shock through your screwdriver.

Even through the large plastic handle?

 

[poor mystic]

There are voltages high enough to make an aura, so do not touch, period.
Sorry, I exaggerate, but the several thousand volts possibly on the cap can get you a shock when you think you're insulated.

 

[(*steve*)]

Even through the large plastic handle?

Yes.

edit: I think the warning of "death on contact" is enough to make anyone pause and think.

Remember that the metal shaft of your screwdriver is embedded in the handle of your screwdriver and this places you closer that you might want to be to 5000V. One guide I read recommended thick rubber gloves as an additional precaution.

 

[War_Spigot]

I wasn't really talking about a microwave cap, I was mostly talking about a camera one, which on the one i was taking apart was only rated at 330V. The link you provided actually has putting a screwdriver across the terminals, followed by shorting each terminal to chassis ground, as one of the methods. The other one being just that second part but with a resistor.

 

[thor]

Thanks guys for all the help so far.

You are right, I will have to prioritize discharging the capacitor first. I just hope that my local electronics store has the 20,000 ohm, 2 watt wire wound resistor that is the heart and soul of the "discharging tool" that Readers Digest New Fix-It-Yourself Manual is recommending for high voltage capacitor discharging.

I will post a picture of the units circuitry after I have safely discharge the capacitor Steve.

Again, thanks guys.