I’m new to AAC and I feel like the janitor at Berkeley who signed up for a MOPS class actually thinking it was about mops. I have a question on grounding of a circuit. I have a two year old Whirlpool WMH31017HZ08 microwave that eats circuit boards and door switches. Whirlpool repair has worked on it at least three times and gave up. Last week it quit again and I got an F1 E4 code which indicates a bad board. I won’t give up and ordered and ordered a new control board and replaced it. I noticed in all the videos and descriptions of replacing these CBS you have to remove a ground wire while removing it. There is no ground wire to the control board housing on mine anywhere. There is a blank sheet metal screw hole. Don’t know if it was left out on purpose or accidentally. Would the omission of a ground wire be a culprit in the continuing problem of failing control boards? Or are the new control boards perhaps in no need of one. Perhaps the ground to the housing is only to protect user. I also noticed the top door switch was burnt where it looked like the spade connector had a bad connection and it had arc marks so I replaced it at the same time. Don’t think a door switch would burn out relay on board. Low tech question to a group of high tech guys, lol.

 

The missing ground could contribute to board failure.

I have found Whirlpool appliances to be really crappy. Will not ever buy one again.

 

Welcome to AAC!

It would be helpful if you circled the areas you want us to look at, and used paragraphs to arrange your thoughts.

Sorry to seem nitpicky about this, but it'll help us help you.

Don’t know if it was left out on purpose or accidentally. Would the omission of a ground wire be a culprit in the continuing problem of failing control boards?

Ground wires connected to the chassis are typically to protect people from electric shock.

I also noticed the top door switch was burnt where it looked like the spade connector had a bad connection and it had arc marks so I replaced it at the same time.

If switches are being damaged due to arcing, it's a bad design. Door switches should *not* be interrupting significant current.

Don’t think a door switch would burn out relay on board.

Not likely.

I noticed in all the videos and descriptions of replacing these CBS you have to remove a ground wire while removing it.

We call them PCB's (Printed Circuit Boards); even if the traces aren't "printed" on the board.

 

I had a microwave oven quite a few years ago with a similar problem. I can't remember the make, It had two switches that were activated by opening the door. The first one disconnected the power to the magnetron circuit and the second one connected a short across the magnetron. It was not designed very well. If you closed the door quickly, the power was applied to the circuit before the short across the magnetron was completely removed. That blew the fuse and damaged the drive circuit. I repaired it twice but there was no way to change the orientation of the door switches. On the third failure, I gave up ang scrapped it.

 

Welcome to AAC!

It would be helpful if you circled the areas you want us to look at, and used paragraphs to arrange your thoughts.

Sorry to seem nitpicky about this, but it'll help us help you.
Ground wires connected to the chassis are typically to protect people from electric shock.
If switches are being damaged due to arcing, it's a bad design. Door switches should *not* be interrupting significant current.
Not likely.
We call them PCB's (Printed Circuit Boards); even if the traces aren't "printed" on the board.

Thanks!