Microwave ME21F707MJT ghost touch issues - FIXED

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written by owen on 2023-Feb-26.

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It started happening about a year into the 4 years of owning the microwave.  Mostly at night you would hear the beep of a number being activated.  This would happen at nights most once or twice a week.  Over time it progressed to the 3 touches, which could usually be ignored until it started activating the LED light, then the vent fan and finally it started to start the microwave itself which was a clear sign that it could not longer be ignored.

First thing I tried was searching online which led to several dead ends.  I Went to the local shop that I bought it from and they said that 4 years is a good run for a microwave and quickly suggested I buy a new one.  I was willing to replace the door but had no luck finding them online.  Its kind of a curse or a blessing that the touch sensitive pad is in the door.

Next step is dismantling the door itself.  If I disconnected the door cable the ghost touches would stop indicating that the problem is definitely in the door.  It seems that even the motherboard itself is inside the door.  Dismantling the door is a test of patience itself - I suggest you search for a youtube video.  The first time I took the door off I removed and reconnected the ribbon cables.  Some people online say that this is a quick fix because sometimes the cables become twisted or disconnected slightly.  After that I reassembled the door and waited patiently.  After about an hour the random ghost touches returned with a vengeance.

At this point we started unplugging the microwave and plugging it in only when we needed to use it.  But this was a temporary fix as the microwave started to cancel itself while food was being heated, lol.  There is an option to turn off the beeps but that bearly when you never know when the microwave is going to activate something that makes a sound like the fan or the light.  So with all my options exhausted I had to go back into the door.

The solution that worked for me

So I waited until I had a day entirely to myself - empty house.  I took the door off the microwave, carefully rested the parts and the screws in the couch.  The pan for this trip is to clean the circuit board with a can of circuit board cleaner.  Since I did not have that particular cleaner on hand I used regular rubbing alcohol.  When you dismantle the door carefully unclip and remove the ribbon cable from the main circuit board.  I placed some alcohol in a small cup then I applied it to the circuit board with a soft makeup brush.  The main purpose of the alcohol is that it evaporates quickly and the soft brush is to gently apply the alcohol without damaging the board.  I cleaned the whole board, back and front, both ribbon cable tips and then I let everything air dry.
After it dried I brushed it with alcohol again, all the leads, circuits then let it dry again.  I clean the brush after every wipe to ensure that any residue/dust gets removed instead of slushed around.  After all that I reassembled everything and the ghost beeps stopped.  The touch pad has also become more responsive since the clean up.  No more missed touches.  So far its been 3 weeks.  Problem solved.

Additional thoughts

I think that over time dust and static might have built up on the circuit board.  These electronics must be suffering from heat death.  Since the fix I have been unplugging the microwave at night since there is no real reason to leave it plugged in when not in use.  There is easy access to the power plug for all the users so this is not much of an inconvenience.  I hope to eke out another 2 years out of the microwave because otherwise its a perfectly good device.
I hope this helps someone out there save some money and not contribute to the world's waste.

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