Main Control Board Testing - Maytag MXR65 Service Manual

Disconnect power before servicing.
Replace all parts and panels before operating.
Failure to do so can result in death or electrical shock.
Of All the parts that are returned to Whirlpool
Corporation for testing, that have been found
to have No Apparent Defect (NAD), it is by far
the electronic control that heads the list. More
control boards have been replaced in the field
without actually fixing the problem than any
other part.
There is not much to test on a control board
that is not basically visual, but depending on
the symptom or failure mode there are items
to test. Always check that all connectors
are firmly connected to the control board.
Sometimes, just unplugging a connector and
re-plugging it onto the control will correct a
problem.
If the failure displayed is a "Memory Failure" it
could be due to a small area failure in a fixed
Random Access Memory (RAM) chip that may
not cause this problem again for years. If a
Memory Failure occurs more than a couple
times a year, then it is cause to replace the
control board.
Blank displays can be checked by opening
the top of the washer and looking at the back
side of the control board. The Display Board
powers the display through a 2-pin connector
with red and white wires located between
J_L and J_01. Make sure this connector is
secure, and provides 4.5VDC. If there is
correct voltage then the Display Board is bad.
Also check that the jumper between the Main
Control Board and Display Board is secure.

MaiN CONTROl BOaRD TeSTiNG

Electrical Shock Hazard
Next, look at the power supply connector
(J_P) on the Main Control Board for PN
models, or at J_P on the Auto Lock Release
Board, on PD models. Make sure this
connector is properly positioned on the control
board. The grey wire should always be to
the left. Then check for proper power (220-
240VAC) at the connector, if these two items
check OK, then the Main Control Board is
defective. If no voltage check the fuses on the
washer rear.
NOTe: When replacing a failed control board
that is out of warranty it could be a good idea
to remove, wrap and store the display as a
service part for future needs. Many complete
control boards are replaced yearly that really
only required a working display board.
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