Samsung MW8490W, about 6.5 years old. Tried microwaving something
today, and the microwave just vibrates and buzzes. It's definately a
60Hz-based buzz. No arcing or odd smells. Everything appears OK
except the metal enclosure vibrates violently like there's a loose
transformer in there.
Oh, it won't heat water, and is drawing only about 350W from the outlet
when running (rear label says 1.5KW).

I can tell you everything you want to know about electronics (well,
almost), but microwaves are somewhat of a mystery to me.

Any ideas on what's wrong, or where to start?

writes:

Samsung MW8490W, about 6.5 years old. Tried microwaving something
today, and the microwave just vibrates and buzzes. It's definately a
60Hz-based buzz. No arcing or odd smells. Everything appears OK
except the metal enclosure vibrates violently like there's a loose
transformer in there.
Oh, it won't heat water, and is drawing only about 350W from the outlet
when running (rear label says 1.5KW).

I can tell you everything you want to know about electronics (well,
almost), but microwaves are somewhat of a mystery to me.

Any ideas on what's wrong, or where to start?

Shorted high voltage diode or magnetron.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

Stay out of that thing. And if you could buy a new magnetron, it would
probably cost more than a new microwave.

Perce


On 02/26/06 06:48 pm wrote:

Samsung MW8490W, about 6.5 years old. Tried microwaving something
today, and the microwave just vibrates and buzzes. It's definately a
60Hz-based buzz. No arcing or odd smells. Everything appears OK
except the metal enclosure vibrates violently like there's a loose
transformer in there.
Oh, it won't heat water, and is drawing only about 350W from the outlet
when running (rear label says 1.5KW).

I can tell you everything you want to know about electronics (well,
almost), but microwaves are somewhat of a mystery to me.

Any ideas on what's wrong, or where to start?

Stay out, why? I know there's a HV capacitor in there, and I know
electronics plenty good enough to know what not to do.

And yes, you're right. Magnetrons are expensive. However, I just
tracked it down to the diode. 0.040 V drop in both directions. Yeah,
it's shorted. Much cheaper than a new microwave.

Percival P. Cassidy wrote:
Stay out of that thing. And if you could buy a new magnetron, it would
probably cost more than a new microwave.

Perce


On 02/26/06 06:48 pm wrote:

Samsung MW8490W, about 6.5 years old. Tried microwaving something
today, and the microwave just vibrates and buzzes. It's definately a
60Hz-based buzz. No arcing or odd smells. Everything appears OK
except the metal enclosure vibrates violently like there's a loose
transformer in there.
Oh, it won't heat water, and is drawing only about 350W from the outlet
when running (rear label says 1.5KW).

I can tell you everything you want to know about electronics (well,
almost), but microwaves are somewhat of a mystery to me.

Any ideas on what's wrong, or where to start?

wrote in message
oups.com...
Stay out, why? I know there's a HV capacitor in there, and I know
electronics plenty good enough to know what not to do.

And yes, you're right. Magnetrons are expensive. However, I just
tracked it down to the diode. 0.040 V drop in both directions. Yeah,
it's shorted. Much cheaper than a new microwave.


Hope that's all it is. In my experiance, HV failures tend to cascade to
several components.

"PipeDown" writes:

wrote in message
oups.com...
Stay out, why? I know there's a HV capacitor in there, and I know
electronics plenty good enough to know what not to do.

And yes, you're right. Magnetrons are expensive. However, I just
tracked it down to the diode. 0.040 V drop in both directions. Yeah,
it's shorted. Much cheaper than a new microwave.


Hope that's all it is. In my experiance, HV failures tend to cascade to
several components.

There aren't that many HV components: HV diode, HV cap, magnetron.

So, conceivably, a bad magnetron took out the diode (though the exact
mechanism isn't clear). The cap is still good or else the main fuse would
have blown. If it was the HV transformer, that wouldn't damage the HV diode.
So, you're left with the HV diode.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

Buzzing is the last thing a microwave does before detonates.

HTH

Steve