Homebrew PCBs

> So what?
> If you notice corrosion you can just bring the oven back to 
> the junk place and take another with you.
> (Keep the transformer if you don't have a battery spot welder yet).
> 
> Microwave ovens are usually free, because they are dumped 
> when still quite easy to repair. The fan blows air into the 
> electrical compartment (usually
> right) and through the cooking chamber, and out the other 
> side. The dirty air does not touch the electrics (it is 
> designed that way to keep food dirt off it). So worst case 
> it'll start to rust somewhere...
> 
> FeCl doesn't gas much, i would not heat cucl, ever, microwave or not.
> 
> ST


Out of dozens of microwaves I've scavenged, all but one would have worked
with minor repairs.  The exception had a shorted transformer.  Sparks!!!

The rest had a blown fuse.  That's it.  Junked for a $0.50 part.  

Ok, in some cases the varistor (spike supressor) had died, and these tend to
fail shorted.  That takes out the fuse as well.  The other way to blow the
fuse is to try to defeat the door locks.  If you look at the wiring, they
are often rigged so the if one of the microswitches (sometimes up to 6!)
doesn't close, then it causes a dead short across the AC, or ties the AC to
ground (which takes out the breaker as well).  Might fry the microswitch
too.

The curious thing is that as ST says, the air vents thru the food
compartment & out the back.  This means the fans get a lot of crap on them,
but everyone I've tested has worked, no matter how grotty.  If the fan did
fail then the thermal cutout (one on the food comparment, one on the
magentron) will trigger.

That junked microwave you walked past works, go grab it.  Dunno about
heating FeCl (I used the double bowl method), but you can dry green wood
with it.  I wish those dudes melting metal would get a move on.

Tony