12 replies to this topic

[Bullstok]

First off, I haven't worked on microwaves before. This is mine so I figure what the hell, right? I know some about the opperation and such. Anyway, the wife says "the microwave is acting wierd" so I have her demonstrate the "wierd" and the sucker starts arcing and throwing sparks through the front vent. I said "woa, turn that damn thing off" and took appart the covers. I found that the high voltage diode has a lightning bolt shape etched in the side of it and this is what was lighting up when it was ran.

My question is this: obviously the diode itself is bad. I can easily order/ install another. But it this a sub problem cause by something else? Or has it going bad possibly caused other issues? How would the testing go? I wasn't wanting to learn about microwaves too much today as I am home sick and feel like crap. Apparently I can't get a sick day where I don't feel the need to fix some damn thing or another. Anyhoo, do I get a new diode or two and see what happens or is there a "leading cause of diode failure" to test? Thanks

[Cactus Bob]

No part failing in your microwave can cause a diode to fail

but

A failing diode can make other parts of your microwave go bad ( cap , control panel , ect )

SO

Get a Diode , install it and try it , works great or not you must start there

[RegUS_PatOff]

there wouldn't be any high-voltage if the Diode was bad

post pictures / video of Diode and sparks
YouTube

[Chat_in_FL]

There seems to be a fairly high failure rate on magnetrons on this model. Not sure if it is related to the cooling system (no seperate fan for cooling the mag & X-fmr). Just an observation, especially since you mentioned "sparks."

[Bullstok]

here it is:

Edited by Bullstok, 06 September 2012 - 05:56 PM.

[RegUS_PatOff]

OOOHHH ... a light-emmitting Diode

It looks like it's arcing across the Diode..
It sure does look bad.
(not just a lightning logo etched onto the part)
You may have other problems, also...

do some resistance / shorts tests:
on the HV Capacitor, Transformer, Magnetron, etc ...
http://appliantology...b2-tech-sheets/

[Bullstok]

Heh, I didn't mean there was a lightening symbol on it and it got deeper and more melted after those pictures, since it actually is glowing hot inside the "groove."

[Cactus Bob]

Please don't do that again . every time you strike a spark even for a split second you come one steep closer to a wiped out capacitor . and if your lucky you can wipe out your control panel as well . if it was still sparking when you stopped your cap is still good , if it stopped your cap is now wiped .

[Bullstok]

Hey, Reg wanted a show

Its all part of the learning experience.

P.s. does this forum have liability insurance...

[RegUS_PatOff]

Heh, I didn't mean there was a lightening symbol on it

that was my thought till I saw it ...

almost any HV MW Diode will work if it has the correct terminals
such as this one
http://www.repaircli...tDetail/1268195

 

 

... P.s. does this forum have liability insurance...

[Bullstok]

Since I may have a fried capacitor now... Can these high volt caps be tested the same way as a regular cap, with direct mfd readings? I see how the service sheet lists the old "rise & drop in resistance" test, but I never use that on regular caps.

[Cactus Bob]

rise and drop never works well on these ultra low value caps

I have a supco MFD-10 that i love ! just a great tester ! I even have a fluke that will do caps and i still grab my mfd-10

[Bullstok]

The results:

diode obviously bad. cap tested ok. i was still a little leery, since you cant really test a cap under load. then i found on tehbay someone selling parts "from damaged units" that were supposedly new. not that i would go this route if i was a "joe homeowner" (the questionable part factor and all that entails) but it was 12 bux with shipping for diode and cap. so "what the hell" says i, and its been working fine since. also the wife don't say "we all get no dinner tonight" cause all the food is still frozen. bonus. thanks everyone. i even thank regus_patoff for helping me try to fry my whole microwave (and possibly giving me nut cancer in the process), because it is still working and i got some kick ass pictures as a result

Edited by Bullstok, 29 September 2012 - 09:54 AM.