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Justin
Justin, Appliance Technician
Category: Appliance
Satisfied Customers: 828
Experience:  Owner of Shaffer's Appliance Service
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I have a Sharp Carousal Microwave R-320FK. When turned on,

Customer Question

I have a Sharp Carousal Microwave R-320FK. When turned on, it falters, then groans loudly and grinds away, stinking like its burning - all within 5 seconds. HAVE TO shut it off ASAP. Is it fixable?
Submitted: 3 years ago.
Category: Appliance
Expert:  replied 3 years ago.

Justin :

Sure it's repairable. What it sounds like, based on your description of the problem, is the magnetron tube has failed. When these fail, they "CAN" make a loud humming noise and stink. It is powered by 4,000 volts DC. A few other things can cause this too. A failed high voltage capacitor and failed high voltage diode can replicate this condition. Most likely though, you have a bad magnetron.

Justin :

You can check the capacitor by setting an ohmmeter on the highest setting (preferably in the megohms) and measuring resistance across the terminals. Normally, the resistance value should start low and rise until it shows infinite. Reversing the leads and testing again will produce same results. For the diode, I've made a video I can link if you'd like. The magnetron should read less than 1 ohm across the filament terminals and should read OPEN between any terminal and chassis ground.

Justin :

If you test the cap and diode and they test normal, you need a magnetron.

Customer :

Is it something I can replace myself, or does it need a service technician?

Justin :

http://www.youtube.com/watch?v=5aYPathqPl0 This is the video to test the diode

Justin :

I don't know what your skill level is. If you can turn a screw driver and feel confident, sure you can do it.

Justin :

You'll need knowledge of using a volt/ohmeter to test a few things

Justin :

Most times with this condition, it's a bad magnetron, but you have to rule the other two things out.

Justin :

Is this an over the range type microwave or a counter top unit?

Customer :

My level of skill is "3 wrenches" out of 4 (from a recent washing machine repAIR MANUAL - HA!). I don't have a volt/ohmmeter, nor have used one. Is it worth getting one, and if so, what quality?

Justin :

The capacitor is silver, looks like a cylindar which has been smashed with two terminals. The HV diode attaches to one terminal of the capacitor and the other end is screwed to chassis ground. The magnetron is a square metal piece with cooling fins around it.

Customer :

This is a counter top unit.

Justin :

It's always worth having a meter. You can pick one up for 25 bucks. It's helpful for a lot of things around the house and it's one of those tools which is nice to have for situations like this. Resistance tests are using the scale which has the Ω sign on the meter. To test the cap, you want to use the HIGHEST setting. Find a meter which can measure in the megohms (millions of ohms) to test the cap. For the diode test, you have to rig a lamp cord with two alligator clips. That test is done on AC volts. You want somewhere around 60 volts.... watch the video :) The mag test involves using the ohms scale on the LOWEST setting. A lot of times, the mag can test normal even if it's bad. You test the two terminals of the magnetron for less than 1 ohm. Then place a lead on a terminal and test the other lead to the metal case and that should read OPEN.

Justin :

Ok, since it's a counter top unit, it might not be worth repairing. Magnetrons usually cost 70 -100 dollars. You can buy a new one for that.

Justin :

You can test the diode and cap though

Justin :

If it's one of those, you might find it's worth it.

Justin :

I'll tell you though that there is a 95% likelihood that your magnetron is the culprit.

Customer :

OK - sounds helpful. You've been very helpful I'm happy to pay you.. I'll watch the video, decide on a meter, and try to isolate the problem. Can I print out this discussion?

Justin :

Yes, just highlight and then right click to print

Justin :

I have three meters... two digital and one analog

Justin :

If you want, I can change this to Q and A. That mode takes us out of live chat and then I can send you an email notification where you can contact me later if needed.

Customer :

Sure, send me the email w/contact info.

Justin :

Ok, Just Answer will send you an email. Just follow the link and you'll have me if you need. Anything else before I exit live chat? Thanks in advance. Please click accept if you're satisfied and please do leave feedback. I'll be happy to help you if you need further assistance.

Justin, Appliance Technician
Category: Appliance
Satisfied Customers: 828
Experience: Owner of Shaffer's Appliance Service
Justin and 3 other Appliance Specialists are ready to help you
Expert:  Justin replied 3 years ago.
Please reply here if you need. I'll be happy to assist you further. Read through our chat and DO watch that video if you want to attempt the diode test. Thanks for using Just Answer.

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