SMH9207ST Samsung Microwave Not Heating and Magnetron always Buzzing when door closed

[Jeff Foster]

Model Number

SMH9207ST

So my wife came home to a buzzing noise on the microwave. She proceeded to try and use it and it did not heat and then went completely dead.

I diagnosed a bad thermostat to the control board and have that fixed and the unit has power again. The other thermostat's seem appear to be fine.

Unlike some of the other threads here I seem to have two issues and I'm not sure if they are related. The buzzing appears to be coming from the magnetron and shuts off when the door is open. According to another thread here I checked the 3 door switches and all appear to be working properly. The next most likely component listed here seems to be the main control board. All the control boards I have found seem to be the one with the number/time display on it. I'm guessing this would be problem with the control board that is behind the buttons.

If I can find the control board and it's not not too expensive, what are the chances this is going to fix the heating issue as well? There seems to be lots of things that could cause the microwave not to heat, but I have not gone through testing those. I don't know how to go about testing the diode, magentron, and capacitors, so I'll have to have someone that knows more about electronics look at that.

Thanks for any advice.

 

[jeff1]

Hi,

That board is starting to come up as NLA for me.
I see Appliance Parts Pros has one in stock....#DE92-02136A

what are the chances this is going to fix the heating issue as well?

Slim.

jeff.

 

[Jeff Foster]

I really appreciate the feedback. I'm disappointed to hear that. So as I mentioned, I'm most likely looking at two problems then?

Apparently what I've been looking at and calling the main control board is actually a relay/power control board. The main circuit board is the part with the LED time display and seems to be more expensive. According to other posts the buzzing is most likely a stuck relay, so the board your posted could fix that.
Any idea what the difference between DE92-02136A and DE92-02136B?

The pictures I found look exactly the same as the one you posted, but the dimensions are all wrong on B according to this site (looks like a decimal place in the wrong place actually). I certainly wouldn't count on getting the right part, but it might be worth a shot.
http://www.searspartsdirect.com/part-number/de92-02136b/0022/401.html


At $70 is's worth replacing the part and easy enough to replace in hopes that it fixes both problems. If it doesn't, what other parts am I looking at? Obviously I can only put so much money into a $300 microwave that is 4 or 5 years old, before I just go and buy a new one. Thanks again for the help!

 

[jeff1]

So as I mentioned, I'm most likely looking at two problems then?

Seems to be so far yes.

Any idea what the difference between DE92-02136A and DE92-02136B?

Nope.
Often when a change has been made, the part# changes also.

At $70 is's worth replacing the part and easy enough to replace in hopes that it fixes both problems

As long as you can return the part ( APP and RC will allow this ), then you might as well try.

jeff.

 

[Jeff Foster]

So far so good.

Great news, the buzzing has stopped when the door is shut. I found the relay board for $30 and figured it was worth a shot. So far I'm into this fix for about $40. Everything I have replaced has fixed something.

1) Unfortunately, as you suggested this did not solve the heating problem. Am I correct that the next easiest thing to check is the diode, capacitor, and finally the magnetron? The diode and capacitor are easy enough to get to and should be easy to check. The magnetron looks difficult to get out for testing.

2) One interesting thing I noticed while doing a heat test is that the turntable doesn't work either. I noticed a possible cause for this is pointing me back at the main control board DE92-02135A. I'm about done with the microwave at this point as I'm afraid how many more things I'm going to find wrong. I sure don't know what caused all these issues to begin with. I guess a bad main board could cause the other parts to not work properly and fail. What are the chances that it's both the main board and some combination of other parts causing it not to heat?

 

[jeff1]

Unfortunately, as you suggested this did not solve the heating problem

What are the chances that it's both the main board and some combination of other parts causing it not to heat?

High now.

Am I correct that the next easiest thing to check is the diode, capacitor, and finally the magnetron?

These can be ohmed checked and a good way to find out if the microwave is creating high voltage or not...
LINK> GE Over-The-Range Microwave | Appliance Aid
LINK> Component Testing | Appliance Aid
LINK> Capacitor Testing | Appliance Aid

jeff.

 

[Jeff Foster]

Well new main board changed nothing so I'm sending it back. I also took the HV Capacitor and Diode out and they tested okay as well. So I guess my next step is to follow the guides you posted to test other components and see where the failure is.

I'm confused as to what would be causing the turn table also to not work. I was really hoping the main board would have been the cause of the heating and turn table issue. Other than the motor itself going out are there any more other causes I should be looking at.

 

[jeff1]

Door switchs, door switch mechanisms, door key(s), are all prime suspects...still...and always for things coming on when the door is closed....board is next after the door stuff.
So what exactly is or is not happening now?....not what happened before, just right now.

jeff.

 

[Jeff Foster]

I previously checked the door switches before switching out the relay board and they tested okay. At least according to the guide I found. There were 3 switches all of which either opened or closed when the door was shut depending on what status they were in with the door open.

So right now the turn table does not work and the microwave does not heat. The microwave turns on and the fan kicks on like it's trying to heat, but nothing gets warm.

 

[jeff1]

So right now the turn table does not work and the microwave does not heat.

Timer counts down?

The microwave turns on and the fan kicks on like it's trying to heat, but nothing gets warm.

We would normally as the next step is to see if the microwave is putting 120 volts into the high voltage transformer....power there but no cooking would indicate a high voltage issue ( mag, transformer, diode, etc )....no input power to the high voltage transformer and we are having a 120 volt issue ( door switch, board ).

jeff.