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-   -   m/w will not heat (http://forum.appliancepartspros.com/microwave-repair/504176-m-w-will-not-heat.html)

horty24 10-23-2012 06:42 PM

m/w will not heat
 
Good day gurus,
So I have a Whrilpool microwaveMH1170XSB-3 that does not produce heat.
So questions are what should I be checking first? The turn table does turn, and light turns on.... Only problem no heat :(
how do I remove it from the cabinets?
Is this an easy repair? I've never opened up a microwave but I have fixed other electronics. Any help would be appreciated.

Gene 10-24-2012 05:39 PM

If you feel comfortable to work under power then unplug the microwave and open the control panel. Remove the wires from the HV transformer primary winding and attach voltmeter probes to these wires. Plug the microwave back. Start the microwave as usual (the door is closed) and measure the voltage. Post the result.

Here are the breakdown diagrams and Parts for Whirlpool MH1170XSB3 Microwave - AppliancePartsPros.com

Gene.
P.S. How the microwave is installed into the cabinet is described in the Installation instructions.

horty24 10-25-2012 05:46 PM

1 Attachment(s)
Quote:

Originally Posted by Gene (Post 777250)
If you feel comfortable to work under power then unplug the microwave and open the control panel. Remove the wires from the HV transformer primary winding and attache voltmeter probes to these wires. Plug the microwave back. Start the microwave as usual (the door is closed) and measure the voltage. Post the result.

Here are the breakdown diagrams and Parts for Whirlpool MH1170XSB3 Microwave - AppliancePartsPros.com

Gene.
P.S. How the microwave is installed into the cabinet is described in the Installation instructions.


Gene thanks for your help, so i took the M/W apart and got to the HV transformer. So just unhook which exact wires? see picture attached. There are 3 wires coming from the trans...

Gene 10-25-2012 06:53 PM

My bad. You said:
Quote:

...I have fixed other electronics...
and I thought you know how a transformer designed.

These 3 wires is from 2 secondary windings and one of them is high voltage with about 2100 volts. Don't even think to touch them, especially when the microwave is plugged in.

There suppose to be another 2 wires on the other side of the transformer. These wires should come from the control board and the door switch. These are the wires which should be connected to the primary winding.

Gene.

horty24 10-25-2012 07:23 PM

Quote:

Originally Posted by Gene (Post 777502)
My bad. You said: and I thought you know how a transformer designed.

These 3 wires is from 2 secondary windings and one of them is high voltage with about 2100 volts. Don't even think to touch them, especially when the microwave is plugged in.

There suppose to be another 2 wires on the other side of the transformer. These wires should come from the control board and the door switch. These are the wires which should be connected to the primary winding.

Gene.

Lol on your quote my bad.......

I'm not an expert but have opened and fixed 3 LCD TVs... Never a microwave.

Anyways so I trace the wire from the control panel to HV transformer and it connects to relay switch 4903 this is a brown wire. The second wire goes from transformer to the magnetron. This Is a white wire. Which then hooks to a circuit on the magnetron with blue lead wire. The blue wires go to door switches.
So should I hook up voltage meter to relay wires?

Gene 10-26-2012 04:38 PM

1 Attachment(s)
If that white wire goes to the thermostat mounted to the magnetron body then this is the second wire (neutral). The first wire (brown) is the correct wire.

The attached wiring diagram will help you.

Gene.

horty24 10-26-2012 05:48 PM

Ok hooked up the multimeter and got 45 . Should have been 120. So I'm guessing bad relay?

Gene 10-26-2012 06:18 PM

Yes, absolutely right. Because this relay is a part of the control board, the correction is to replace the control board.

- The control board Part number: W10197767

Part number: W10197767

Gene.
P.S. Just in case, check the thermostat mounted to the magnetron for continuity.

horty24 10-27-2012 05:35 PM

Quote:

Originally Posted by Gene (Post 777674)
Yes, absolutely right. Because this relay is a part of the control board, the correction is to replace the control board.

- The control board Part number: W10197767

Part number: W10197767

Gene.
P.S. Just in case, check the thermostat mounted to the magnetron for continuity.


Gene, so I rechecked everything and my relay is actaully good.... after loking at the schematics a bit closer I was testing voltage on wrong wires....
So I tested the correct wires and im getting 122 volts. Seems like now its either the HV transformer, the capacitor the magnetron or diode.
I do have continuity at the thermo at magnetron as well as the other two.
Ok so how do I test the HV transformer, the capacitor the magnetron or diode. Is it even worth it? or just go buy a new M/W?

Thanks for your help so far.

Gene 10-29-2012 04:46 PM

Quote:

Originally Posted by horty24 (Post 777836)
...Ok so how do I test the HV transformer, the capacitor the magnetron or diode...

...Is it even worth it? or just go buy a new M/W?...

The capacitor is definitely good. Otherwise it will blow the fuse.

The HV transformer is the last thing to think about because their failure is very rare.

You can find the instructions on how to check the diode in one of our previous threads; http://forum.appliancepartspros.com/...e-testing.html

If the diode is good then the magnetron is the culprit.


Only you can decide if it worth it.

- The magnetron Part number: W10210845

Part number: W10210845



- The diode Part number: W10163432

Part number: W10163432



Gene.


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