Re: Removing MOT and Cap

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Mike Nolley by way of Terry Fritz <twftesla-at-qwest-dot-net>" <nolleym-at-willamette.edu>

> There's a microwave at my school that's free for the taking. How would I go
> about safely removing the xfrmer and the cap? It's been unplugged for a few
> weeks, but I'm guessing it would still be prudent to discharge the cap. Can
> I just short it with a screwdriver? Are there any other sources of voltage I
> should be aware of? (BTW, I'm not interested in the magnetron.)

    I have taken apart quite a few microwave ovens in my time, and I have a
few pieces of advice you
might find useful.  First, always discharge the cap.  Though the capacitors
in microwave ovens
frequently have resistors built into them or bridging  their terminals, it
is a great idea to get into
the habit of discharging capacitors, especially if you will be working with
them later.  A screwdriver
is not the best option, since you may not be able to reach both terminals.
Instead use high voltage or
test lead wire (preferrably the kind with thick rubber insulation) instead.
 You can get this from any
electronics store besides Radio Shack.  It is ok to hold the wire by the
insulation for 2kv, but just to
be safe (and consistent--for higher voltage capacitors) use 2 pvc pipes
about 1.5 feet long taped to
either side of the wire terminals. If you can't find hv wire, check the
capacitor casing for the
internal resistor mark--it might be safe enough if you are 99% sure it is
discharged to use a
screwdriver.  Nothing else in the microwave will carry any residual charge.
 It is perfectly safe to
handle the potentially lethal transformer inside immediately after
unplugging it--just as long as *NO*
capacitor is attached.
    Other bits of advice.  Not all microwave oven trannies are made alike.
Some fairly decently sized
ones will go up in smoke if you short the terminals (these are typically
dark cored--resin dipped jobs
made by "Advance" transformer company).  Avoid these.  Most of the rest of
them have decent silicon
steel cores with decent core to coil insulation.
    Removing the cap and tranny can be time consuming.  Sometimes the
screws will be stripped, or
rusted, especially if the microwave has been sitting out in the elements
for any length of time.  A
little bit of elbow grease will usually do the trick.  If you have to snip,
cut, or excessively fold
metal to get to the transformer, it isn't worth it.  The microwave oven
casing will cut you up before
you cut it up.
    Finally, be careful not to cut yourself on the sharp edges of the
casing.  Once you are done looting
the microwave, put the casing back together, so that you or others don't
cut yourselves when disposing
of it.  Thats all.  Have fun.

            --Mike