Not typical microwave oven issue
 

my microwave - an old Sharp w/convection - has a nasty habit.
When the power goes on and off, as in a storm or not, occasionally it
will spontaniously start up, usually with the convection feature on -
'cause it gets very hot. I haven't noticed that the microwave was on,
just heat.

has anyone fixed an issue like this?
I'm thinking the low voltage power supply needs some new caps.
Maybe some transient suppression on the Triacs.
Is there any "typical" circuit or block illustrations for this.
I can reverse engineer it if I can get to it but some idea would help.

Otherwise it works fine. I just need to remember not to leave it
plugged in.

thanks

Not typical microwave oven issue
 

wrote:
my microwave - an old Sharp w/convection - has a nasty habit.
When the power goes on and off, as in a storm or not, occasionally it
will spontaniously start up, usually with the convection feature on -
'cause it gets very hot. I haven't noticed that the microwave was on,
just heat.

has anyone fixed an issue like this?
I'm thinking the low voltage power supply needs some new caps.
Maybe some transient suppression on the Triacs.
Is there any "typical" circuit or block illustrations for this.
I can reverse engineer it if I can get to it but some idea would help.

Otherwise it works fine. I just need to remember not to leave it
plugged in.

thanks

I have a very similar microwave, When thepower went out last afterwards
as soon as the door gets opened it throws the circuit breaker outside.
Has anyone got any tips here? For their age these ovens work pretty
good.

Not typical microwave oven issue
 

"toranaboy14" wrote in message
ups.com...

I have a very similar microwave, When thepower went out last afterwards
as soon as the door gets opened it throws the circuit breaker outside.
Has anyone got any tips here? For their age these ovens work pretty
good.

Check the MOV across the line. Mine died and emitted smoke after a couple of
years.

Not typical microwave oven issue
 

On Fri, 01 Sep 2006 04:13:06 GMT wrote in Message id:
:

my microwave - an old Sharp w/convection - has a nasty habit.
When the power goes on and off, as in a storm or not, occasionally it
will spontaniously start up, usually with the convection feature on -
'cause it gets very hot. I haven't noticed that the microwave was on,
just heat.

has anyone fixed an issue like this?
I'm thinking the low voltage power supply needs some new caps.
Maybe some transient suppression on the Triacs.
Is there any "typical" circuit or block illustrations for this.
I can reverse engineer it if I can get to it but some idea would help.

Otherwise it works fine. I just need to remember not to leave it
plugged in.

No idea on how to fix this, but I would suggest leaving the door open when
not in use, rather than remembering to unplug it.

Not typical microwave oven issue
 

toranaboy14 wrote:

I have a very similar microwave, When thepower went out last afterwards
as soon as the door gets opened it throws the circuit breaker outside.
Has anyone got any tips here? For their age these ovens work pretty
good.

this is an interlock failure, and is a dangerous condition. The
resistor that pops the breaker/fuse can not be counted on to continue
doing its job repeatedly, so if it starts behaving again of its own
accord its just got one step more dangerous, and now has just one
switch between working and frying you with door open - and bear in mind
the other one has already failed.

Note interlock failure can be caused by door misalignment, bad
microswitch or a mechanical interlock problem.


NT

Not typical microwave oven issue
 

As said, this is a safety feature.

The interlocks prevent you from being irradiated. The interlocks have
to engage in a certain order or the fuse in the oven will blow (or the
circuit breaker at your Breaker box trips). Here is a link to the
RepairFAQ about the interlocks:

http://www.repairfaq.org/sam/micfaq.htm#micintrlk

wrote:
toranaboy14 wrote:

I have a very similar microwave, When thepower went out last afterwards
as soon as the door gets opened it throws the circuit breaker outside.
Has anyone got any tips here? For their age these ovens work pretty
good.

this is an interlock failure, and is a dangerous condition. The
resistor that pops the breaker/fuse can not be counted on to continue
doing its job repeatedly, so if it starts behaving again of its own
accord its just got one step more dangerous, and now has just one
switch between working and frying you with door open - and bear in mind
the other one has already failed.

Note interlock failure can be caused by door misalignment, bad
microswitch or a mechanical interlock problem.


NT

Not typical microwave oven issue
 

nvic wrote:
As said, this is a safety feature.

The interlocks prevent you from being irradiated. The interlocks have
to engage in a certain order or the fuse in the oven will blow (or the
circuit breaker at your Breaker box trips). Here is a link to the
RepairFAQ about the interlocks:

http://www.repairfaq.org/sam/micfaq.htm#micintrlk

wrote:
toranaboy14 wrote:

I have a very similar microwave, When thepower went out last afterwards
as soon as the door gets opened it throws the circuit breaker outside.
Has anyone got any tips here? For their age these ovens work pretty
good.

this is an interlock failure, and is a dangerous condition. The
resistor that pops the breaker/fuse can not be counted on to continue
doing its job repeatedly, so if it starts behaving again of its own
accord its just got one step more dangerous, and now has just one
switch between working and frying you with door open - and bear in mind
the other one has already failed.

Note interlock failure can be caused by door misalignment, bad
microswitch or a mechanical interlock problem.


NT

This makes sense, a couple of months back I had to realign one of the
switches because the thing wouldnt run. The missus has a habit of
slamming it shut half the time. Ill look into it later on and if
nothing comes from Ill look for another.

Thanks all.

Not typical microwave oven issue
 

"toranaboy14" wrote in message
ups.com...

This makes sense, a couple of months back I had to realign one of the
switches because the thing wouldnt run. The missus has a habit of
slamming it shut half the time. Ill look into it later on and if
nothing comes from Ill look for another.

Slamming the door can misalign the switches. Train her to close it.

Not typical microwave oven issue
 

even a block diagram would be nice, huh?
When you just plug it in with the door closed, does anything on the
panel come on?
Most have a fuse in line (or should) and if the current draw is enough
to pop your house breaker it should pop the internal fuse first.
Your breaker may be a GFI if you are plugged into a kitchen outlet. In
that case, if you measure between a prong and ground on the micro plug
you may find a leakage resistance. About the only thing connected with
the door open that isn't with it closed would be the internal lamp.
I suppose there may be some that turn off the control ckt until the
door is opened. If so, the low voltage power is where to look.
still, read again above re current.


On 31 Aug 2006 21:19:47 -0700, "toranaboy14"
wrote:


wrote:
my microwave - an old Sharp w/convection - has a nasty habit.
When the power goes on and off, as in a storm or not, occasionally it
will spontaniously start up, usually with the convection feature on -
'cause it gets very hot. I haven't noticed that the microwave was on,
just heat.

has anyone fixed an issue like this?
I'm thinking the low voltage power supply needs some new caps.
Maybe some transient suppression on the Triacs.
Is there any "typical" circuit or block illustrations for this.
I can reverse engineer it if I can get to it but some idea would help.

Otherwise it works fine. I just need to remember not to leave it
plugged in.

thanks

I have a very similar microwave, When thepower went out last afterwards
as soon as the door gets opened it throws the circuit breaker outside.
Has anyone got any tips here? For their age these ovens work pretty
good.

Not typical microwave oven issue
 

GOOD CALL - kitty cat

I wondered what that "MONITOR" switch and resister (or not) was for.
Logically, I should have figured it out.

That Monitor switch has a short life cycle. I wouldn't trust it after
ONE activation.


On 1 Sep 2006 10:43:30 -0700, wrote:

toranaboy14 wrote:

I have a very similar microwave, When thepower went out last afterwards
as soon as the door gets opened it throws the circuit breaker outside.
Has anyone got any tips here? For their age these ovens work pretty
good.

this is an interlock failure, and is a dangerous condition. The
resistor that pops the breaker/fuse can not be counted on to continue
doing its job repeatedly, so if it starts behaving again of its own
accord its just got one step more dangerous, and now has just one
switch between working and frying you with door open - and bear in mind
the other one has already failed.

Note interlock failure can be caused by door misalignment, bad
microswitch or a mechanical interlock problem.


NT