• ** 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
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Loud Buzzing in Samsung Over the Range Microwave

cxanthos

Premium Member
Joined
Apr 22, 2009
Messages
27
Location
San Diego
Model Number
SMH9151
Brand
Samsung
Age
1-5 years
My Over the Range Samsung microwave has developed a very loud buzzing sound whenever it is heating. When running at cooking percentages the buzzing cycles on and off corresponding with the heating cycle. Despite the sound, it seems to heat fine. Any ideas? Is it safe to continue to use? Thank you.
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
38,179
Location
Murray, Utah 84107, United States
It sounds like it might be the mag tube, but it could be any of the high side components. It's safe to use. There are a lot of safety devices built in. Is the buzzing getting louder or staying the same?
 

cxanthos

Premium Member
Joined
Apr 22, 2009
Messages
27
Location
San Diego
It was tolerable for the last few weeks but now it has become really loud in the past couple of days.

Thanks.
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
38,179
Location
Murray, Utah 84107, United States
It's going to be difficult to figure out what part you need while it's still heating. The diode is the most common noise maker but when it goes out the microwave doesn't heat it just makes a loud hum. The noise cycles on and off when cooking at 50% power, right? Does it completely stop or is it barely audible? Can you access the high side components or will you need to take it down? Do you have a VOM? (Volt Ohm Meter)
 

cxanthos

Premium Member
Joined
Apr 22, 2009
Messages
27
Location
San Diego
When it is at 50% it cycles completely off and then full loudness. The buzzing is not audible at all when it goes into a rest cycle. I will need to take it down to access the high side components. Yes I do have VOM.

Thanks.
 

cxanthos

Premium Member
Joined
Apr 22, 2009
Messages
27
Location
San Diego
I checked the serial number and it's an S9 (September, 2009), so I guess it doesn't apply. It does look, however, like I can access the upper components without having to take it down.

Thanks.
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
38,179
Location
Murray, Utah 84107, United States
OK, Unplug the microwave and short the two terminals on the High Voltage Capacitor together. Let's start with the easy obvious things first. Check for any loose screws on the fan motor and bracket. Make sure the fan blade isn't hitting anything and that's not loose on the shaft. Check all the screws that hold the High Voltage transformer in place. Make sure they are all tight. Next check the H.V. Diode. It's easier to just remove it from the H.V. capacitor and ground screw If your meter has a diode check, touch the probes to the two ends of the diode. You should briefly read some resistance one way, then switch the meter probes and you should read open or 1. When you reinstall the diode make sure the ground screw is tight. Try running the microwave with the cover off and see if you can tell where the noise is coming from.
 

cxanthos

Premium Member
Joined
Apr 22, 2009
Messages
27
Location
San Diego
Finally got it all taken apart. Diode and HV capacitor check out and magnetron is quiet. It's the transformer that's making all the noise. The metal base plate it sits on works as a great sound amplifier too! I placed the order today for the replacement part at appliancepartspros.com and they had it in stock. I also noticed the diode ground screw is a sheet metal screw and doesn't get very tight. I'm going to replace it with a machine screw and lock nut to make sure it stays tight. Thanks for your help.
 

boomster

Member
Joined
Nov 21, 2012
Messages
1
Location
Brunswick
Help!

Finally got it all taken apart. Diode and HV capacitor check out and magnetron is quiet. It's the transformer that's making all the noise. The metal base plate it sits on works as a great sound amplifier too! I placed the order today for the replacement part at appliancepartspros.com and they had it in stock. I also noticed the diode ground screw is a sheet metal screw and doesn't get very tight. I'm going to replace it with a machine screw and lock nut to make sure it stays tight. Thanks for your help.
Mine is having the exact same issues and I'm 99% sure it's the transformer. Could you tell me what part number is the transformer for this microwave please?? Was it easy to replace it? It's getting so loud and if it's an easy fix I'd rather do this myself then buy a new microwave.

THANK YOU!
 
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