The other day, my wife turned on the time cook instead of using the microwave as a timer. Consequently, it became extemely hot and has gone blank. There is nothing on the screen at all. I've checked the circuit breaker and the wall plug and everything is fine. I had one wire (ground) from the front panel to the interior of the machine that had been pinched between the frame and the housing. I got it out and taped the small section of exposed wire. I found the two fuses inside and ordered them from GE. They came, I put them in and plugged the microwave back into the wall. NOTHING. Any suggestions?
Thanks,
Lou
First, check power to the outlet using a lamp or radio you know works. The
fuse or circuit breaker at your service panel may have blown/tripped due to
an overload or fault in the microwave oven or some other appliance. You may
just have too many appliances plugged into this circuit - microwave ovens are
high current appliances and should be on a dedicated circuit if possible. If
you attempt to run a heating appliance like a toaster or fryer at the same
time, you *will* blow the fuse or trip the circuit breaker.
If you find the fuse blown or circuit breaker tripped, unplug everything from
the circuit to which the microwave is connected (keep in mind that other
outlets may be fed from the same circuit). Replace the fuse or reset the
circuit breaker. If the same thing happens again, you have a problem with
the outlet or other wiring on the same branch circuit. If plugging in the
microwave causes the fuse to blow or circuit breaker to trip immediately,
there is a short circuit in the power cord or elsewhere.
Next, try to set the clock. With some ovens the screen will be totally blank
following a power outage - there may be nothing wrong with it. Furthermore,
some ovens will not allow you perform any cooking related actions until the
clock is set to a valid time.
Assuming these are not your problems, a fuse has probably blown although
a dead controller is a possibility.
If the main fuse is upstream of the controller, then any short circuit
in the microwave generator will also disable the controller and display.
If this is the case, then putting in a new fuse will enable the
touchpad/display to function but may blow again as soon as a cook cycle
is initiated if there is an actual fault in the microwave circuits.
Therefore, try a new fuse. If this blows immediately, there may be a
short very near the line cord, in the controller, or a defective triac
(if your oven uses a triac). If it does not blow, initiate a cook cycle
(with a cup of water inside). If the oven now works, the fuse may simply
have been tired of living. This is common.
If the fuse still blows immediately, confirm that the controller is
operational by unplugging the microwave generator, power relay, and/or
triac from the controller. If a new fuse does not now blow when a cook
cycle is initiated - and it appears to operate normally - then one of
the components in the microwave generator is defective (shorted). See
the section: "Microwave generator problems".
Some models have a thermal fuse as well and this may have failed for no
reason or a cooling fan may not be working and the oven overheated (in
which case it probably would have died while you were cooking something
for an important guest - assuming you would use a microwave oven for such
a thing!).
Other possible causes: bad controller power supply or bad controller chip.
The most common way that the controller circuitry can be harmed is by a power
surge such as from a lightning strike. Hopefully, only components on the
primary side of the power transformer will be affected. In some cases,
circuit board traces may have been vaporized (but repair may still be
possible by simply jumpering across the crater). Assuming that the main fuse
checks out, then check the power supply for the controller next. Also check
I hope this helps..
Goodluck..
for bad solder connections.
ohh srry for the last line in my previous post.
Also check for bad solder connections..
Goodluck..
Please don't forget to rate the solution
I just wanted to explain everything clearly.Anyways in general , try to set the clock. With some ovens the screen will be totally blank following a power outage - there may be nothing wrong with it. Furthermore, some ovens will not allow you perform any cooking related actions until the clock is set to a valid time.
Other possible causes: bad controller power supply or bad controller chip.
LVT stands for low voltage transformer.
Open thermal fuse should read as a dead short - near zero ohms.
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The panel display is fried. you'll need to remove and replace it...this the sort of thing you enjoy doing?
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This appears to be a canned answer. If you would have read my email, I've already done most of what you have listed here. I would like specific information regarding the microwave I wrote to you about not general information any and all microwaves.
Lou
I just pressed the clock set and the screen is still blank. I'll check tomorrow the new fuses I put in to see if they are still good. I'll look online for the controller and chip you mentioned.
Thanks,
Lou
In removing the front panel I found a wiring diagram and trouble shooting guide. The guide is relative simple, I just need to confirm what I found.
It starts with the simple question is the display lit? Answer NO. Check the circuit breaker and outlet. They are fine. Next check the fuse. The fuse if OK. Next check the LVT(?)on the printed circuit board. Since it didn't identify what the LVT is, I'm not sure what I needed to look for. If that checks out is says to check the thermal cut out. I found that on the diagram and pulled in out of the unit. I placed the Ohm probes on the connection ends and the needle didn't move. If it had gone to 0 Ohms, that would indicate an open circuit correct? Since the needle didn't move to "0", (assuming the circuit is "closed") the instructions say to replace the printed circuit board. If the circuit is open, that it says to replace the thermal cut out (temperature sensor). I just need to confirm that if the needle had gone to "0" Ohms, the circuit would be open.
Thanks,
Lou
Based on your response, I need to ask another question regarding the Thermal Cut Out. Since I don't know how the TCO actually works, with the power off (unplugged), what reading should I get from the TCO. I made the assumption that if the Ohm reader went to "O" it would be an open circuit. Could that mean the TCO is actually closed? I would think the TCO would act much like a fuse. If the fuse gets too hot, it breaks causing the circuit to close and stopping the flow of electricity to the components. Maybe I'm not using the correct terminology here but I need to make sure, I'm not misreading what the "0" Ohm reading means for the TCO.
Thanks,
Lou
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