Microwave turntable
 

I have a Sharp MW. The turntable sometimes rotates
clockwise,othertimes it rotates counter-clockwise.If someone knows the
reason why,I would appreciate an answer.No one so far has been able to
explain this.Just some FOOD for thought! Thanx

Microwave turntable
 

Lee burch wrote in message
...
I have a Sharp MW. The turntable sometimes rotates
clockwise,othertimes it rotates counter-clockwise.If someone knows the
reason why,I would appreciate an answer.No one so far has been able to
explain this.Just some FOOD for thought! Thanx

Most models reverse every time the MW is started. In some cases, the food
should be stirred part way though the cycle. After you do that, the
turntable reverses, allegedly to help cook more evenly.

Microwave turntable
 

Lee burch wrote in message
...

I have a Sharp MW. The turntable sometimes rotates
clockwise,othertimes it rotates counter-clockwise.If someone knows the
reason why,I would appreciate an answer.No one so far has been able to
explain this.

What did the manufacturer say when you messaged
the Sharp web site ?

--
Don Phillipson
Carlsbad Springs
(Ottawa, Canada)

Microwave turntable
 

Well, if it always turns in one
direction the food will tangle, so you must
untangle ..... just kidding. Many
gear-head motors that run on 110 AC,
have "shading rings" to set up the
magnetic field so they always rotate in the
same direction. These are 1 turn chunks
of copper that will go through and/or
around the steel laminations. I have
noticed in the last few years, many small
motors like that, don't have shading
rings and will start in a random direction.
I guess if it doesn't make any
difference, like in a microwave
turntable, it makes
the motor $0.00001 cheaper. BTW, my
microwave does the same thing.

Lee burch wrote:
I have a Sharp MW. The turntable sometimes rotates
clockwise,othertimes it rotates counter-clockwise.If someone knows the
reason why,I would appreciate an answer.No one so far has been able to
explain this.Just some FOOD for thought! Thanx

Microwave turntable
 

Art Todesco wrote:
Well, if it always turns in one direction the food will tangle, so you must
untangle ..... just kidding. Many gear-head motors that run on 110 AC,
have "shading rings" to set up the magnetic field so they always rotate
in the
same direction. These are 1 turn chunks of copper that will go through
and/or
around the steel laminations. I have noticed in the last few years,
many small
motors like that, don't have shading rings and will start in a random
direction.

What kind of motors do you think those are?

AFAIK, without shading rings a simple induction motor will not self
start. But, there are all sorts of small motor designs around now I
never encountered when I was a kid, just think about what's in a modern
automobile.

Perhaps they're using DC motors, two phase AC motors, or some kind of
stepper motor for those microwave turntables now, driven by a few
components on the appliance's circuit board.

Based on what Edwin said, I doubt that the starting direction is really
"random".

Jeff

I guess if it doesn't make any difference, like in a microwave
turntable, it makes
the motor $0.00001 cheaper. BTW, my microwave does the same thing.


I know my 4 year old GE microwave's turntable always rotates in the same
direction as my grandma's Victrola's, but it might be interesting for
the OP to run some tests or even, G-d forbid, RTFM and let us know if
it's really random.

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.98*10^14 fathoms per fortnight.

Microwave turntable
 

Jeff Wisnia wrote:
Art Todesco wrote:
Well, if it always turns in one direction the food will tangle, so you
must
untangle ..... just kidding. Many gear-head motors that run on 110 AC,
have "shading rings" to set up the magnetic field so they always
rotate in the
same direction. These are 1 turn chunks of copper that will go
through and/or
around the steel laminations. I have noticed in the last few years,
many small
motors like that, don't have shading rings and will start in a random
direction.

What kind of motors do you think those are?

AFAIK, without shading rings a simple induction motor will not self
start. But, there are all sorts of small motor designs around now I
never encountered when I was a kid, just think about what's in a modern
automobile.

Perhaps they're using DC motors, two phase AC motors, or some kind of
stepper motor for those microwave turntables now, driven by a few
components on the appliance's circuit board.

Based on what Edwin said, I doubt that the starting direction is really
"random".

Jeff

I guess if it doesn't make any difference, like in a microwave
turntable, it makes
the motor $0.00001 cheaper. BTW, my microwave does the same thing.


I know my 4 year old GE microwave's turntable always rotates in the same
direction as my grandma's Victrola's, but it might be interesting for
the OP to run some tests or even, G-d forbid, RTFM and let us know if
it's really random.

Jeff
You're right. I even saw a motor with a
mechanical direction unit. If it went the
"wrong" way, it bounced off a ratchet
device and went the other way. But I
thought a small motor with a rotor would
self start. It's just the synchronous
ones that
wouldn't start by themselves unless
something it added. I know old (very
old) clocks
had to be "spun" to get them going.
They too, would go either way. But,
as you stated, it's probablythe way the
whole thing was designed.

Microwave turntable
 

061217 0918 - Lee burch posted:

I have a Sharp MW. The turntable sometimes rotates
clockwise,othertimes it rotates counter-clockwise.If someone knows the
reason why,I would appreciate an answer.No one so far has been able to
explain this.Just some FOOD for thought! Thanx

That's the nature of the type of syncronous motor installed in most
turntables. It depends on where in the AC cycle the motor is started as to
what direction it will go. If the motor is turned on at the rise of the
cycle, the motor will go one way; if on the downturn of the cycle, it will
go the opposite. It doesn't really matter, as long as the turntable turns.

Microwave turntable
 

Lee burch wrote:
I have a Sharp MW. The turntable sometimes rotates
clockwise,othertimes it rotates counter-clockwise.If someone knows the
reason why,I would appreciate an answer.No one so far has been able to
explain this.Just some FOOD for thought! Thanx

No it isn't food for thought; it is just an
ignorant thought.
The damn thing is made to operate that way! Read
the manual!