My Maytag repair pages are not intended to be a repair guide. It is just a means to share some of the things I learned while repairing my Maytag Neptune washer and I hope you find the information helpful.
Maytag Neptune 5500 Washer Motor Control Board C Phase Drive Circuit Schematic & Repair Information
My Neptune washer included very useful troubleshooting / diagnostic document inside the washing machine, but it does not include schematic diagrams of the control boards.
I drew the c phase of the motor drive circuit schematic so I could understand how it worked. This circuit is basically repeated for each of the 3 motor phases.
The first image of the board corresponds to the top right section of the schematic below. R1 & R3 are in the center, C39 is above Z1, and R10 & R12 are in the top right corner of the picture.
The image below the schematic is of the C phase drive section of the motor control board and corresponds to the schematic diagram.
Here is my experience with repairing the motor control board in this washer. The Q5 mosfet blew out on c phase of the motor drive circuit and the 75 ohm resistor labeled J12 driving this mosfet was fried.
I replaced both IRF644 mosfets Q5 & Q6 driving the c phase windings, the 75 ohm gate drive resistor and the IR2101 high and low side driver IC3.
The repaired washer operated properly until the 7th run which had a larger load than any of the previous runs and then c phase blew out again and this time the damage extended to the zener diode Z1.
After this blowout I focused more on checking the motor windings for problems, and tried to find any evidence of the motor wiring harness insulation being pinched or worn thru.
Since the blowout occurred during a much heavier load than the previous runs and I couldn't find any motor or motor wiring problems. I concluded that the Q5 mosfet blowout might have been caused by the breakdown of surge suppression diode D9.
This time I replaced diodes D9 & D11, mosfets Q5 & Q6, gate resistor labeled J12, IR2101 high low driver IC3, and the 15 volt zener diode Z1 and added inline fuses between the c phase motor harness wires and the control board.
Once I was confident the problem was resolved I removed the inline
fuses that I had added to the c phase wiring harness.
Since this repair the washer has been operated thru hundreds of run cycles without incident.