writes:

mm wrote:
On 26 Feb 2006 16:35:21 -0800, wrote:


Sam Goldwasser wrote:
writes:

Samsung MW8490W, about 6.5 years old. Tried microwaving something
today, and the microwave just vibrates and buzzes. It's definately a
60Hz-based buzz. No arcing or odd smells. Everything appears OK
except the metal enclosure vibrates violently like there's a loose
transformer in there.
Oh, it won't heat water, and is drawing only about 350W from the outlet
when running (rear label says 1.5KW).

I can tell you everything you want to know about electronics (well,
almost), but microwaves are somewhat of a mystery to me.

Any ideas on what's wrong, or where to start?

Shorted high voltage diode or magnetron.

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Any quick checks that can be made? Should the two terminals to the mag
have some low resistance? (I'm not sure what they connect to)

I'm also going to read up some more on how these things work.

The most important thing is to either not mess with the cage around
the microwave part, or to put it back EXACTLY the way you find it. At
first the Amana girl refused to send me a schematic (back when I
didn't realize how simple they are) because she thought I'd radiate
myself or my eyes to death. Apparently the metal side of the oven,
where the electronics are, is not enough to keep the waves inside.

You might want to get a microwave tester (10 dollars at Radio Shack)
to make sure there is no leakage. I calibrated mine by pulling the
door open a little but less than it took to have the oven turn off.
now that the ovens latch instead of just close, this might be harder
to do. The RS tester was calibrated fine to begin with afaict.

There's no cage around the microwave parts. It's in the open once the
outside shell has been removed. Nothing that I'm messing with here
looks real critical....just high voltage stuff. I'm not remove the mag
or anything.

Right. Just try not to electrocute yourself in the process. If you don't
remove the magnetron, there is no critical seal you'll be affecting.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.