Carosel won't turn and won't heat
Investigate these three areas if your microwave won't heat
A diode is an electronic component that readily passes current in one
direction only and blocks the flow of current in the opposing direction.
If your microwave's diode has become defective, your microwave will not
heat. Test the diode to determine if this is the cause of your problem.
Replace it if it is defective.
Testing a diode
NOTE: Before you test your diode, make sure your microwave is unplugged, and that you discharge the microwave's capacitor.
Whether it is shorted or open, a defective diode will most likely show
some sign of defect. Defective diodes will usually emit an electrical
burning smell, signifying its defectiveness. Also, it may have split in
two, or it may exhibit a burned crack, or possibly even a blistered
A shorted diode is indicated by a loud humming noise from the high
voltage transformer, and no heat produced when a cook cycle is
initiated. Whereas little or no heat produced in your microwave, with an
absence of a humming noise is indicative of an open diode. In either
case, the diode has to be replaced.
With your microwave unplugged, and your capacitor discharged, use
extreme caution to remove the lead that leads to the capacitor. You can
leave the ground connection attached. The side of the diode that goes to
the ground is usually marked with a dot, stripe, or arrow. Set your
ohmmeter to R x 10,000 or higher. Touch the positive meter probe to the
anode and the negative meter probe to the cathode to measure the
resistance across the diode terminals. Remember that the cathode is on
the side that goes to the ground, which is often marked by a dot,
stripe, or an arrow.
A normal diode, that is a non-defective diode, will read anywhere from
50,000 to 200,000 ohms. Differences in microwave make and model account
for this large range in resistance readings.
Reverse the meter probes and measure resistance while touching the
positive probe to the cathode and the negative probe to the anode.
Reversing the probes like this should result in a reading of infinity.
Unless a bleeder resistor is present. The presence of a bleeder resistor
would produce a reading of the value of the resistor.
High Voltage Capacitor
A capacitor is an electrical device which stores electricity. A
defective capacitor may be why your microwave is not heating. The
capacitor will have to be tested to determine if this is the cause of
your problem. A defective capacitor will have to be replaced before your
microwave will work again. Make sure you discharge the capacitor before
you test it, though.
A defective magnetron is the third possible cause of why your microwave
is not heating. Test your microwave's magnetron. Replace it if it is
Testing a magnetron
NOTE: Before you test this component, make sure your microwave is unplugged, and that you have discharged the capacitor.
There are two tests to conduct in order to determine whether or not a
magnetron has become defective. If you receive results other than what
are detailed below, you will have to replace your microwave's magnetron.
Each test is described for you here:
TEST 1: Locate your magnetron and label each of the wires attached to it
so that you know which wires are to be replaced where. Set your
ohmmeter to the lowest resistance scale. Take a resistance measurement
between each of the magnetron's terminals by touching each probe to one
terminal each. Reverse the probes and take a second resistance
measurement. Each measurement should read less than one ohm.
TEST 2: Set your ohmmeter to its highest resistance scale. Touch one of
the meter's probes to a magnetron terminal. Touch the other probe to the
metal magnetron housing. Take special caution to not touch the two
probes together. This could result in an inaccurate reading. This test
should produce a reading of infinity - indicating an open circuit.
Read the tips on the below links on how to replace your microwave oven's diode and how to discharge the capacitor.
I hope the above is helpful.
Oct 27, 2011 |
Sharp R-930AK Convection/Microwave Oven