• ** REMEMBER! **The microwave can still shock you even unplugged!!

    ALWAYS discharge the high-voltage capacitor first if you even think your hands will come close to any HIGH VOLTAGE components.

    Jeff mentions this: Anything in the high voltage ( magnetron, capacitor, diode, wires to and from ):
    ...Use a metal ( not the shiny chrome type ) screw driver with a insulated handle to short across ( touch both at the same time ) the terminals of the high voltage capacitor to discharge it.

    From Jeff's site: http://www.applianceaid.com/component-testing.php

    Jake

HMB5050 Bosch Microwave - Circuit Board or Bust?

Thomas CGY

Member
Joined
Mar 16, 2015
Messages
1
Location
Calgary
Model Number
HMB5050
Brand
Bosch
Age
1-5 years
Hi Everyone,

First time poster but I'm very motivated to work this out and I'd sincerely appreciate advice. I have a Bosch HMB 5050 microwave that's about 2 years old. It has seen very light use and is installed in a cabinet with a bosch surround, all per Bosch specs. A few months ago, our door latch started to get finicky and it needed to be closed a couple of times in order to truly close. As a result, we were sometimes fairly forceful with the door (not slamming it but when it failed to fully close, we opened it up then pushed it closed again).

After about 3 months of the finicky door, something more major changed. When we put something in and closed the door (and it was fully closed), once the start button was pushed, it didn't cook. worse still, the microwave would be "on" and the turntable would twitch a bit and the inside light would be dimly lit. It wouldn't accept user inputs. If I unplugged it and plugged it back in, it would sometimes immediately go and start moving the turntable a bit and dimly engage the light but other times, it would allow me to microwave something with success.

I pulled the unit out of it's cabinet and opened it up. I noticed that the door was finicky because the door mechanism was only screwed to the frame on one side of the mechanism, not both sides or on the top or bottom. As a result, when we had been closing the door, the mechanism wouldn't engage correctly because the connection to the frame would just flex a bit. I took the coward's way out and superglued the door mechanism to the microwave frame on a couple of sides and the closing mechanism was very clean and works well.

However, I still have a problem in that if I plug the microwave in, it sometimes works fine but after that use or two, once the door is opened (as you intend to put something in and cook it), the turntable starts to twitch and the interior light is dimly lit and it doesn't accept any commands. I can unplug the microwave, plug it back in and some of the time (about 50% of the time), I can put something in, close the door and cook it to completion. The rest of the time, when I plug it back in it either starts with the turntable twitch and dim interior light or I can enter a cook time (as if everything is okay) but when I press the start button, it starts twitching the turntable, dim interior lighting and pushing buttons does nothing. The only course of action thereafter is to unplug it and start again.

So I think that in our months of "roughness" with our finicky door mechanism, we may have cracked the circuit board but I would really appreciate others' insight on this before I sink $230 for a new board. I have a multimeter and a set of tamper-resistant screw heads so I can take this unit apart as needed and test a fair bit of electrical work.
 

jeff1

Appliance Tech - Moderator
Staff member
Joined
Oct 10, 2004
Messages
23,621
Location
Ontario, Canada
Hi,

I noticed that the door was finicky because the door mechanism was only screwed to the frame on one side of the mechanism, not both sides or on the top or bottom. As a result, when we had been closing the door, the mechanism wouldn't engage correctly because the connection to the frame would just flex a bit. I took the coward's way out and superglued the door mechanism to the microwave frame on a couple of sides and the closing mechanism was very clean and works well.
Have any pictures of this?

I found HMB5050/01 HMB5050/02

but when I press the start button, it starts twitching the turntable, dim interior lighting and pushing buttons does nothing. The only course of action thereafter is to unplug it and start again.
I don't believe I have seen one do that.

jeff.
 

Tmann

Member
Joined
Feb 4, 2018
Messages
1
Location
Louisville ky
Tonight my microwave same model number started doing the same thing. When you put something in it to cook press start the fan does not run, light does not light when cooking however it does heat. Then when you open the door the light is dimly lit, turntable twitches sometimes other times spins completely as if it is still runnng. Have turned off the breaker for 30 minutes hoping this would reset it but it did not.

Does anyone have any ideas as to what may be causing this?

Thanks
 
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