• ** REMEMBER! **The microwave can still shock you even unplugged!!

    ALWAYS discharge the high-voltage capacitor first if you even think your hands will come close to any HIGH VOLTAGE components.

    Jeff mentions this: Anything in the high voltage ( magnetron, capacitor, diode, wires to and from ):
    ...Use a metal ( not the shiny chrome type ) screw driver with a insulated handle to short across ( touch both at the same time ) the terminals of the high voltage capacitor to discharge it.

    From Jeff's site: http://www.applianceaid.com/component-testing.php

    Jake

FGMV175QBA Frigidaire Microwave - Strange control board activity question

Mcnabb75

Premium Member
Joined
Sep 26, 2018
Messages
58
Location
Greenville SC
Model Number
FGMV175QBA
Brand
Frigidaire
Age
1-5 years
So, working on this microwave and it was tripping the breaker. Determined one of the interlock switches had gone out. Replaced it and it still tripped the breaker. Determined it was a bad control board. Replaced the same microswitch because the new one fried out. Got a new board and put it in and when I plugged it up the turntable would come on when I opened the door. Only the turntable and not the light.
Went back through all the switches and wiring. All worked properly. Figured it was a bad board. Got a new board. Same thing. Turntable would spin with the door open. So I went back and put the old board in. Behold, it works fine. Doesn't trip the breaker and runs fine.

So the question is, even if I misdiagnosed the original board and it was just a couple of bad switches, shouldn't the new control boards have worked properly? All the wiring is working and connected properly. No switch has been reversed etc etc. And like I mentioned, the microwave works fine now.
More of an opinion thread.
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
36,058
Location
Murray, Utah 84107, United States
The problem may not be with the microswitches but the microswitch bracket being out of adjustment. The way to check is by opening and closing the door while checking continuity. The monitor switch, also called the dead man switch, shorts L1 to N while the door is open so one of the other switches needs to open the power circuit when the door is opened or closed
 

Mcnabb75

Premium Member
Joined
Sep 26, 2018
Messages
58
Location
Greenville SC
Sorry for the delay. Went back and checked everything. Bracket is good, switches good, and old board still works. 🤷🏻‍♂️ I know bad boards are rare but it seems that was the case. Nothing I did would get the new boards to work.
Thank you
 
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