PROBLEM: only during the microwave function, the unit makes loud "buzzing" noise 1 to 2 seconds after start up. All other functions work fine...other than buzzing. No sparks or other abnormalities.
The unit heats items in a normal time range, ie, nearly boils a cup of water in 1 minute.
There is NO abnormal noise while convection bake or broil is used.
As stated, other than the "buzzing or rattling" noise, the unit seemily works fine.
The unit is "new" (no warranty, bought as is) so there is no recourse with manufacturer.
Any insights welcome.
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Re: Viking Micro noise
The noise is probably from the high-voltage transformer. When it
is overloaded, the excess magnetic field it produces vibrates its wire
coils. Odd that it only happens for a brief time. It is
either defective itself (in which case it may go a long time) or it is
getting overloaded by the magnatron/capacitor/diode on its output (in
which case it will get worse shortly)
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Aug 12, 2011 - 10 posts - 2 authors
My Whirlpool MT4155SPS-2 microwave oven has recently started to buzz loudlywhen operated. The sound is getting louder and more frequent ...
Whirlpool making intermittent loud buzzing noise Microwave ...
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If your microwave buzzes loudly and produces no heat you probably have a defective power .... I have a whirlpool oven range and it's less than a year old. .... Humming sound stops when I open door to remove food, but when door is closed, ...
Unit uses a Magnetron and likely a power board called an inverter to run it. Someone would have to open the unit in a way where they might pinpoint where the sound is coming from and then take action--does not of course sound normal or good to me.
The noise filter is to block electrical noise, not auditory noise. "Noise" in electronics means any unwanted or unintended electrical signal.
The purpose of the noise filter is to help prevent any electrical noise generated in the wiring of the microwave from getting into your house wiring, which could cause interference with or disruption of other devices.
If your microwave is making auditory noise, then it may be a loose cover or panel, a rubber bumper fell off the high voltage transformer, or one of the components is failing.
A loud buzz, hum, or groan is usually a
shorted high voltage rectifier diode, but a sound like gurgling into an
empty coffee mug is one symptom of a failed magnetron, and yet the magnetron can
be bad without that sound.
If either of those two were bad, it would not cook.
It could be that the magentron has failed. Does it make a loud hum or buzzing noise when you try to use the microwave only function? If it does, chances are that the magnetron has shorted out. The replacement cost can be as high as the cost of a new oven, so it rarely makes sense to fix.
A loud buzz is a symptom of a shorted magnetron or high voltage diode. Would recommend that you take it to a qualified repair facility if you want it repaired, but if the magnetron has failed, the part costs can equal that of a new oven.
My microwave was totally dead. Things I discovered:
1) There is an easily replacable fuse accessed by taking off the top front vent cover (two screws on top, gently massage off) and then the inside plastic grill. UNPLUG before doing this!
2) Pop off two wires on either end of fuse holder for safety. Then pop out fuse and replace.
For more extensive help, there is an evelope with a wiring diagram inside the case on the inside wall! Very helpful when diagnosing the surface lamp problem (I forgot to plug the ballast back in when I closed up the bottom).
Sounds like you just fried your magnetron. Normally when they go bad, they make a very loud noise like what you described. The smell concerns me because you may have ruined the waveguide as well. If the magnetron burns through the protective painted surface of the waveguide, the waveguide is ruined. In most microwave ovens this means replacing the entire unit because the waveguide is not replaceable. Putting a new magnetron in a damaged waveguide will result in the same arcing and eventual failure. In addition to the magnetron, the following components are part of the same high voltage network:
Magnetron Thermal Cut-Out
Any one of these components could have also been damaged. I DO NOT recommend taking any voltage measurements inside the HV network. Potentials of over 4000 volts can be reached and make it very dangerous for the do-it-yourselfer. Taking resistance readings with the unit unplugged is strongly encouraged. If you decide to pursue a repair, inspect the magnetron tip and inside of the waveguide first. If the magnetron is melted and/or there are burn marks inside the waveguide, a new microwave may be a in order. This actually may be a better option than an expensive repair. I hope you find this advice helpful.