I was given a non-functioning LG microwave range hood that was built in Feb 2006. According to the previous owner, one morning he came down and it was dead: no power, no lights, nothing.

I had a chance to crack it open tonight, and on the chance it might be something simple (we can always hope) I changed the 20 amp ceramic line fuse. NOTHING.

Later in the week I will dig out my multi-meter; I know enough to be afraid, and have read about the need to discharge the capacitor. Since this MW has been off for quite a while, when I tried to jump the capacitor terminals with a screwdriver there was no spark.

But...what would cause a less than 2 year old MW to go dead like this? No power to the panel; no power to the fan; to the lights... I thought I would start by checking continuity tracing the line coming in. The unit comes with a little parts layout diagram and a schematic, and even a lists of test for some of the high voltage components using a multi-meter. I see in the diagrams that the fuse block is mounted on what is called a "noise filter". If indeed the fuse did not blow, then perhaps this is the culprit? I just don't understand why the entire unit is dead; I expected to find a blown fuse.

And...if it is an interlock of some sort, wouldn't at least an interior light be on or something??? I see in th ediagram there are three switches: a primary switch, monitor switch, and secondary switch. Would any of these stuck open cut power to the entire unit?

Finally, would a malfunctioning oven thermostat or Magnetron thermostat do this? A bad (open) H.V. transformer? I figure if I keep listing parts somehow I will stumble upon something... (!!!!)

There is of course the possiblity that the fuse I put in is defective; when I get that meter out I will check for continuity of both the old and new.

Thanks for the advice; I am stumped for now and am throwing in the towel for tonight.

Robert (who hates to throw things away.)

Thanks Gene. I see both of them on the parts layout diagram; I remember seeing the mgt thermostat when I opened it up. I am not sure yet how to get to the oven thermostat but if the mgt is not open I will check the other. Now that you have pointed them out to me, I found them on the circuit diagram and see how either one, without continuity, would leave the entire circuit open and thus, no power to the microwave.

If by chance I am lucky enough to isolate the problem to this issue, where does one buy a replacement thermostat (whichever one it might be?)

I am heading out of town tomorrow, but will post my findings after the weekend for others' benefit.

Robert

Robert

I could not find an exact match to my existing oven cavity thermostat listed above; what I did find was a thermostat with the same 230-degree opening rating, but that would re-set at 190-degrees. It also comes with 1/4" terminals instead of 3/16", but they have reducers available.

Is there any reason not to use this substitution? It seems like with the upper rating the same it would provide the same protection if it overheats for some reason, and with the lower re-set rating would "fix itself" until the problem occurred again. I don't know why the first one went bad; but if it is a recurring problem this will at least give me a chance to sort it out.

Thanks.

Robert

thanks!

I was curious about whether it would re-set if I put it in the freezer, and in fact tried that first; no such luck.

Thanks for the part number.

Guys, I can't thank you enough. I have a LMV2053SB and it "died" about two years ago. It semed like it blew a fuse but that wasn't the case so I gave up.

After reading this thread, I test both thermostats and found the magnetron thermostat open. I put it in the freezer for about an hour, test it, and it was closed! That was about a month ago and it is still going strong (and microwave get a workout in my house of three teenagers plus friends)! Gene, Thanks for you expert advice and Robert, Thank you for hating to throw things away (like me). You guys rock!