Cooks intermittently runs fine. Door switches all meter test ok. Testing the 2 thermal switches one tests open one closed. Magnitron open Hood closed. Seems correct?? Was hoping all sensers should meter open....
Any ideas?
Willaim,
I have gone through the testing on the Mini Manual and still have intermittant operation. When I turn the oven on there is a secondary humming noise that indicates the oven is working. I can tell at once if the seconday hum is not there. When the oven starts that econd hum sort of kicks in a second or two after the oven starts. 6 months ago I seated all 4 of the door switches and the oven worked non stop for like 6 months. All of a sudden it went out again like before. Is there more to testing these switches than just continuity or no continuity? Can they be partially bad?
I was going to retest all switches for resistance and connections, as well as Magnatron and other high voltage connections per your Blog
Thanks,
Rwood
There
should be a "mini-manual" hidden inside the unit behind the
control panel or hidden on the left side behind the grille, which is
very helpful when troubleshooting & testing.
Can you scan and e-mail or photocopy & fax the "schematic diagram" portion of the mini-manual to me?
Feel free to contact me directly for more information & help.
We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.
William E. Miller
[email protected]
http://www.microwavedisplay.com
fax 866-481-2802
This model may utilize a triac to control the cooking power. If so, that's another wild card in the mix.
If this is a problem in the triac circuit, it's pretty important to catch and fix it before it fails hard and smokes part. When that happens, you can't get part values and the whole board would have to be replaced.
Since you found the mini-manual, would you scan and e-mail or copy and fax (in detail mode) at least the "schematic diagram" page to me?
If it does not have a triac, I'd say you have a bad switch or two. If they've never been replaced, you can probably count on it. And / or possibly a failing relay or connection on the control board.
If you only need a switch, you can order one from us for $5 postpaid.
It's actually best to replace both the primary and secondary switches. But the schematic will help me figure that out for you.
We regularly repair control units for
customers nationwide by mail for $39.95 postpaid in about a week.
Feel free to contact me directly for more information & help.
We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.
William E. Miller
[email protected]
http://www.microwavedisplay.com
free fax 866-481-2802
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The
high voltage diode converts the A/C power output of the transformer
to D/C, doubling the voltage to nearly 5,000 volts. This high
voltage powers the magnetron which emits the energy that cooks the
food. If the diode burns out, a lower A/C voltage reaches the
magnetron, which is not sufficient to power the magnetron. When the
diode fails it is often visibly burned out. If it appears to be
good, it can be tested with a volt-Ohm meter capable of testing
diodes. High voltage diodes frequently fail and are one of the most
common points of failure in a microwave oven. A regular meter with a
diode checker will not work to check these diodes. You have to use a
meter with a 9 volt battery or put a 9 volt battery in series with
the diode to check it.
If
the microwave does not heat, one of the door switches might be
defective. Microwave ovens normally have three door switches, if any
of them fail the microwave does not turn on and does not heat. Check
the switches for continuity with an Ohm meter.
If
the microwave oven doesn't heat the magnetron tube might have burned
out. The magnetron uses high voltage, high current DC power to
generate the microwave frequency that cooks the food. If the
microwave oven is turned on when it is empty this can cause the
magnetron to burn out. Once it is burned out it has to be replaced,
it's not repairable.
If
the microwave doesn't heat the high voltage capacitor might be
defective. The high voltage capacitor works with the high voltage
diode to convert the output of the transformer to DC voltage and to
double the output voltage. If the capacitor is burned out the entire
high voltage circuit stops working properly. The high voltage
capacitor can be checked with a special VOM meter which has a
capacitance testing capability. Be aware that the high voltage
capacitor can retain a charge of more than 3,000 volts and can
injure or kill a person if not handled properly. Only trained
technicians should perform this type of testin
If
the microwave does not heat, the high voltage transformer might be
burned out. Microwave ovens produce a very high voltage in order to
power the magnetron antenna, which emits the energy that cooks the
food. When a high voltage transformer fails it will usually arch and
have a burning smell
If
the microwave doesn't heat the thermal fuse may have blown. It can
be tested for continuity. Watch our fuse testing video for more
information.
If
the microwave doesn't heat the thermoprotector may have tripped. This
is a safety device to prevent the microwave from overheating. It can
be tested for continuity to see if it's blown.
The
high voltage diode converts the A/C power output of the transformer
to D/C, doubling the voltage to nearly 5,000 volts. This high
voltage powers the magnetron which emits the energy that cooks the
food. If the diode burns out, a lower A/C voltage reaches the
magnetron, which is not sufficient to power the magnetron. When the
diode fails it is often visibly burned out. If it appears to be
good, it can be tested with a volt-Ohm meter capable of testing
diodes. High voltage diodes frequently fail and are one of the most
common points of failure in a microwave oven. A regular meter with a
diode checker will not work to check these diodes. You have to use a
meter with a 9 volt battery or put a 9 volt battery in series with
the diode to check it.
If
the microwave does not heat, one of the door switches might be
defective. Microwave ovens normally have three door switches, if any
of them fail the microwave does not turn on and does not heat. Check
the switches for continuity with an Ohm meter.
If
the microwave oven doesn't heat the magnetron tube might have burned
out. The magnetron uses high voltage, high current DC power to
generate the microwave frequency that cooks the food. If the
microwave oven is turned on when it is empty this can cause the
magnetron to burn out. Once it is burned out it has to be replaced,
it's not repairable.
If
the microwave doesn't heat the high voltage capacitor might be
defective. The high voltage capacitor works with the high voltage
diode to convert the output of the transformer to DC voltage and to
double the output voltage. If the capacitor is burned out the entire
high voltage circuit stops working properly. The high voltage
capacitor can be checked with a special VOM meter which has a
capacitance testing capability. Be aware that the high voltage
capacitor can retain a charge of more than 3,000 volts and can
injure or kill a person if not handled properly. Only trained
technicians should perform this type of testin
If
the microwave does not heat, the high voltage transformer might be
burned out. Microwave ovens produce a very high voltage in order to
power the magnetron antenna, which emits the energy that cooks the
food. When a high voltage transformer fails it will usually arch and
have a burning smell
If
the microwave doesn't heat the thermal fuse may have blown. It can
be tested for continuity. Watch our fuse testing video for more
information.
If
the microwave doesn't heat the thermoprotector may have tripped. This
is a safety device to prevent the microwave from overheating. It can
be tested for continuity to see if it's blown.
The
high voltage diode converts the A/C power output of the transformer
to D/C, doubling the voltage to nearly 5,000 volts. This high
voltage powers the magnetron which emits the energy that cooks the
food. If the diode burns out, a lower A/C voltage reaches the
magnetron, which is not sufficient to power the magnetron. When the
diode fails it is often visibly burned out. If it appears to be
good, it can be tested with a volt-Ohm meter capable of testing
diodes. High voltage diodes frequently fail and are one of the most
common points of failure in a microwave oven. A regular meter with a
diode checker will not work to check these diodes. You have to use a
meter with a 9 volt battery or put a 9 volt battery in series with
the diode to check it.
If
the microwave does not heat, one of the door switches might be
defective. Microwave ovens normally have three door switches, if any
of them fail the microwave does not turn on and does not heat. Check
the switches for continuity with an Ohm meter.
If
the microwave oven doesn't heat the magnetron tube might have burned
out. The magnetron uses high voltage, high current DC power to
generate the microwave frequency that cooks the food. If the
microwave oven is turned on when it is empty this can cause the
magnetron to burn out. Once it is burned out it has to be replaced,
it's not repairable.
If
the microwave doesn't heat the high voltage capacitor might be
defective. The high voltage capacitor works with the high voltage
diode to convert the output of the transformer to DC voltage and to
double the output voltage. If the capacitor is burned out the entire
high voltage circuit stops working properly. The high voltage
capacitor can be checked with a special VOM meter which has a
capacitance testing capability. Be aware that the high voltage
capacitor can retain a charge of more than 3,000 volts and can
injure or kill a person if not handled properly. Only trained
technicians should perform this type of testin
If
the microwave does not heat, the high voltage transformer might be
burned out. Microwave ovens produce a very high voltage in order to
power the magnetron antenna, which emits the energy that cooks the
food. When a high voltage transformer fails it will usually arch and
have a burning smell
If
the microwave doesn't heat the thermal fuse may have blown. It can
be tested for continuity. Watch our fuse testing video for more
information.
If
the microwave doesn't heat the thermoprotector may have tripped. This
is a safety device to prevent the microwave from overheating. It can
be tested for continuity to see if it's blown.
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