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Old Sharp microwave

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Norm:
BTW bj ours is/was bright green instead  of blue....
which probably means nothing....hmm?
Norm :)

Wolvenar:
Believe it or not, her microwave is likely SIGNIFICANTLY easier to fix.

In the microwave circuit ( non inverter style) There are very few components..
Leaving out the control circuits, ( switches, timers, relays etc..)
The components are basically:
A step up coil, a capacitor, a rectifying diode, and a magnetron.

There is a chance of residual high voltages, but most microwave capacitors today have been built with internal resistors/resistance to bleed power off to make the device safer for dum dums like me that love tearing things apart.

I have fixed a LOT of microwaves over the years.
Ironically I started this by scrapping a lot to get the ceramic magnets in the magnetrons for a wind gen.

click on thumbnail for larger image


I have never yet seen a bad coil. A rough guesstimate, and this is counting only totally non-working unit.
I'm not counting display troubled ones (which are a LOT).
About 60% of he microwaves I have messed with are nothing more than a blown fuse, or heat fuse and/or thermostat.
The rest, in order of most common failures:  rectifier, capacitor, magnetron, timer.
There was only one where it was any of the switches or relays ( only 1 of near 200 or so).

If anyone is interested, I suppose I can get into the theory of operation, and how the circuit works.
A microwave is amazingly simple, if you don't count digital controls and timers.


 

Wolvenar:
Norm yours sounds like a LED lit unit. And from the sounds of it you have a failed capacitor.

Capacitors, particularity of that machines era, fail and leak well before they should.
This is generally because these were made in china with an incomplete stolen electrolyte recipe.
More on that here http://en.wikipedia.org/wiki/Capacitor_plague
The result is the electrolyte breaks down earlier than it should and becomes acidic, pretty much ruining the capacitors value.
Sometimes leaking caps leak enough to get on things around it and cause corrosive damage or shorting.

I collect/repair game consoles, and one of the most common problems of these from the 90s is failed capacitors.
I'll add a pic here for an example if I can dig one up.

--Edit --

Here is a couple from a LCD tv I repaired
Don't mistake what you see on these for glue, it DOES look a little like it.

Click image for (much) larger view

bj:
   Good read Wolv.  Once again, Thanks.

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