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Microwave - won't heat unless I open door and then close it
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I have a Whirlpool Gold (model GMH6185XQ-1) and it won't heat unless I trick it into working. I have to enter in the cook time and press start and let it start running (runs, but gives no heat and cannot hear any magnatron load), open the door, then close the door and press start again. It will then begin heating and I can hear the load of the magnatron kicking in.
I wonder if the first time it starts cooking, the capacitor has no charge to begin with so it won't heat, but when I open and close the door and press start again, the capacitor was charged from the first round so it can begin working as normal.
I tested both door switches with a multimeter and they seem fine.
Another way I can get it to work is to put in my cook time, press start and let it begin running, lower the temp and then raise it back up. I can then hear the microwave "kick in" as the load of the magnatron begins working.
I was going to just replace the capacitor and diode but wasn't sure if they were the problem. The capacitor is only $20, but the little diode is $46!
I already replaced the main circuit board, but it had no effect.
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Originally Posted by: Sean_Woods  ...let it start running (runs, but gives no heat and cannot hear any magnatron load)... Would the turntable motor work at that time? If it would not then the problem is a bad secondary interlock switch. Gene.
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The turntable works every time, whether or not it is heating. Everything works as normal except the heat until I interrupt the microwave and restart it.
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Rank: Advanced Member
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Originally Posted by: Sean_Woods ...Another way I can get it to work is to put in my cook time, press start and let it begin running, lower the temp and then raise it back up. I can then hear the microwave "kick in" as the load of the magnatron begins working...
...I already replaced the main circuit board, but it had no effect... I'm assuming you used the microwave cook, not the convection. Then playing with the oven temperature, which is functional for convection only, does not make any sense. I never seen any kind of an intermittent problems with HV capacitors and/or HV diodes. I will blame in such situation only the control board. You said that you already replaced it. I have no clue what else could cause it. Gene.
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Thanks for the help so far, Gene. When I said I adjust the temp, I actually mean I lower the power setting to a lower % such as 90%, then back up to 100% and it begins working.
I actually have not tried the convection setting, but have never used it so it doesn't concern me.
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Rank: Advanced Member
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Originally Posted by: Sean_Woods ...When I said I adjust the temp, I actually mean I lower the power setting to a lower % such as 90%, then back up to 100% and it begins working... Sean, This points even more to a faulty control board. Did it do exactly the same after you replaced the circuit board? What is the part number of it? Gene. P.S. BTW the model number you posted looks like incomplete. Verify and repost it please.
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I did forget the letter V at the end of the model # of the microwave; it should be GMH6185XVQ-1.
The symptoms it has now are exactly the same as before I replaced the board. The model # of the board is W10249319.
I didn't post this earlier, but when I first bought the microwave about 2 years ago, the magnatron was bad and it made sparking sounds as soon as I bought it. I had that replaced under warranty.
The problem with the non-heating started around 5-6 months ago (out of the 1 year warranty).
I put the new board in 3 days ago.
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If you feel comfortable to work under the power then you may want to verify 120 VAC to the HV transformer primary winding right after the start button was pressed. Open the control panel and remove the wires from the transformer primary winding. Connect the voltmeter probes to these wires and push the start button. The door should be closed. If the reading is correct then the problem is somewhere within the high voltage part of the microwave. Gene.
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Thanks. That is VERY good advice. I will try that. I remember the "one hand rule" when working on live electricity from back in shop class :)
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OK, I need some help figuring out if I am doing this correctly. Looking at the tech sheet, on the first page, the red and brown wires coming off of the Turbo Relay go to the transformer. Those are the wires I have tested.
Disconnecting the wires, I get no power directly on the wires when I press start....I am assuming I am leaving them connected to the Turbo Relay while testing.
When I press start, I get 118 volts coming off of Turbo Relay going to the red wire and very little voltage going to the brown wire - the microwave is running, but no heat.
When I open and close the door and press start again, the power flip flops and the brown wire now has 118 volts and the red wire has very little voltage.
Update: I just disconnected each wire one at a time (red and brown coming off the Turbo Relay) and tested each after pressing start. Neither one has any sufficient power when disconnected and the microwave running....maybe 6 volts (tried it when it had no heat and also when I open/closed the door and the heat worked and got the same results both times). But, I can disconnect the red wire and I can still get heat when opening and closing the door. When disconnecting only the brown wire, I can never get it to heat.
I don't consider myself an electrician by any means and am not sure what to make of this.
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Microwave - won't heat unless I open door and then close it
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