Microwave arcs after years of normal operation
 

Our 5 year old Kenmore microwave has run perfectly with no abuse, no
metal used while cooking, etc.
We have also used it to warm our plates, and typically we warm one,
two, or three dinner plates for between 1 and 2 minutes total. They
always emerge nicely warmed, not hot but just right. The plates are
similar to what we'd call stoneware but not as dense, perhaps some sort
of clay substance made by Pfaltzgraff. This shows the exact plate but
not the material, at http://www.pfaltzgraff.com/ca/13937.htm .

We have warmed plates in it for most of the 5 years since we discovered
this seems to work quite well. Today, while warming two plates, we got
a strong arc after only a second or two, which upon subsequent test
seems to occur behind the white plastic square piece on the right side
of the cavity (assume this is the magnetron horn?)

We shut it off immediately and then experimented further; it appears to
still function, warming a glass of water normally, warming a container
of rice normally, etc. However, placing the plates back in causes an
almost immediate arc.

So, what's changed? Have the plates somehow become more/less load now
(unlikely; we tried two other plates as well with the same result.)

I'm guessing maybe a buildup of grease or residue in the magnetron area
may have changed it's parameters somehow, to the extent that it's no
longer 'happy' being asked to warm plates.

Ideas? (Other than "don't do that" please...)

Microwave arcs after years of normal operation
 

wrote:
Our 5 year old Kenmore microwave has run perfectly with no abuse, no
metal used while cooking, etc.
We have also used it to warm our plates, and typically we warm one,
two, or three dinner plates for between 1 and 2 minutes total. They
always emerge nicely warmed, not hot but just right. The plates are
similar to what we'd call stoneware but not as dense, perhaps some sort
of clay substance made by Pfaltzgraff. This shows the exact plate but
not the material, at http://www.pfaltzgraff.com/ca/13937.htm .

We have warmed plates in it for most of the 5 years since we discovered
this seems to work quite well. Today, while warming two plates, we got
a strong arc after only a second or two, which upon subsequent test
seems to occur behind the white plastic square piece on the right side
of the cavity (assume this is the magnetron horn?)

We shut it off immediately and then experimented further; it appears to
still function, warming a glass of water normally, warming a container
of rice normally, etc. However, placing the plates back in causes an
almost immediate arc.

So, what's changed? Have the plates somehow become more/less load now
(unlikely; we tried two other plates as well with the same result.)

I'm guessing maybe a buildup of grease or residue in the magnetron area
may have changed it's parameters somehow, to the extent that it's no
longer 'happy' being asked to warm plates.

Ideas? (Other than "don't do that" please...)



It could just be a buildup of crud somewhere, once it starts to arc, you
have to clean and patch it up good to prevent it from arcing again.

I've never heard of warming plates in a microwave oven, I would think
that if the plates themselves get warm, they're probably not microwave
safe. I would at least put a cup of water in there as a load.

Microwave arcs after years of normal operation
 

I've never heard of warming plates in a microwave oven, I would think that
if the plates themselves get warm, they're probably not microwave safe. I
would at least put a cup of water in there as a load.

Good advice ... a cup of water is easy and prevents damage to the oven
(which seems to have happened in this case).

Microwave arcs after years of normal operation
 

" wrote:

Our 5 year old Kenmore microwave has run perfectly with no abuse, no
metal used while cooking, etc.
We have also used it to warm our plates, and typically we warm one,
two, or three dinner plates for between 1 and 2 minutes total. They
always emerge nicely warmed, not hot but just right. The plates are
similar to what we'd call stoneware but not as dense, perhaps some sort
of clay substance made by Pfaltzgraff. This shows the exact plate but
not the material, at http://www.pfaltzgraff.com/ca/13937.htm .

We have warmed plates in it for most of the 5 years since we discovered
this seems to work quite well. Today, while warming two plates,

Just on their own ? I wouldn't do that.


we got
a strong arc after only a second or two, which upon subsequent test
seems to occur behind the white plastic square piece on the right side
of the cavity (assume this is the magnetron horn?)

We shut it off immediately and then experimented further; it appears to
still function, warming a glass of water normally, warming a container
of rice normally, etc. However, placing the plates back in causes an
almost immediate arc.

So, what's changed? Have the plates somehow become more/less load now
(unlikely; we tried two other plates as well with the same result.)

I'm guessing maybe a buildup of grease or residue in the magnetron area
may have changed it's parameters somehow, to the extent that it's no
longer 'happy' being asked to warm plates.

Ideas? (Other than "don't do that" please...)

Maybe the plates now contain less moisture. Is it now sort of wintertime and the
humidity will have fallen.

Can't explain why it didn't happen every winter though.

Graham