So this unit is the combination wall over and microwave unit. Its worked fine until yesterday the display is just dead, black nothing. the Microwave light comes on when you open the door but nothing on the panel.
Tried turning the power (breaker) off many times and for long periods and still nothing.
One thing i did notice is when you open the microwave door the light inside it comes on but no light when you open the oven door?
Please help, thought i would order a new control panel?
Part #2 here
http://www.appliancepartspros.com/control-panel-parts-for-maytag-jmw3430wp00.html
I can only guess here, but the fact that you have no display at all makes me think that you have a loss of power at or to the electronic control board/boards.
The problem is there are three very expensive boards in this appliance. Which one is bad or are two or more bad? Only testing will tell you.
You might be able to get the board rebuilt. If I had to guess without testing I would pic this board…
http://www.appliancepartspros.com/whirlpool-sms-power-supply-wpw10286791-ap6018743.html
It seems to be a power board. If nothing else, you could pull it and look it over for burnt traces, bulged capacitors etc.
Just a personal comment on this oven. I can’t believe what they want for the parts on this, $1700 for a control panel? You’ve got to be kidding!
http://www.appliancepartspros.com/whirlpool-panl-cntrl-w10349502-ap4909243.html