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Slightly OT: how to test magnetrons?

PostPosted: Sun Feb 06, 2011 9:47 pm
by ilyaz
I've collected about a dozen microwave magnetrons. I originally planned to scrap them but none of the local yards take them at all, or take them as light iron. So I want to try selling them on eBay as replacement parts. The question is: how can I test them if they are good? I pulled some of them out of working ovens and some out of broken ones plus I threw them all into a bucket so might have damaged them in the process. So how can I make sure it's actually a functioning magnetron?

Thanks!

Re: Slightly OT: how to test magnetrons?

PostPosted: Mon Feb 07, 2011 10:50 am
by cuppoor
If you are not an electrician or a EE then I would recommend not trying to test them. The autotransformer and rectifier produce lethal high voltage and current and doubly dangerous since it's not isolated from line voltage. If you don't have the knowledge and proper test equipment then don't try it. It's not worth it.

Re: Slightly OT: how to test magnetrons?

PostPosted: Mon Feb 07, 2011 12:34 pm
by ilyaz
cuppoor wrote:If you are not an electrician or a EE then I would recommend not trying to test them. The autotransformer and rectifier produce lethal high voltage and current and doubly dangerous since it's not isolated from line voltage. If you don't have the knowledge and proper test equipment then don't try it. It's not worth it.


All the magnetrons I am trying to test have already been pulled out of the microwaves, so there is no danger of electric shock.

I found the following page on testing magnetrons: http://www.ehow.com/how_5864880_test-magnetron-microwave-oven.html

The question is whether I can assume that a magnetron is functional if it passed both tests described in steps 4 and 5.

Thanks.

Re: Slightly OT: how to test magnetrons?

PostPosted: Mon Feb 07, 2011 8:48 pm
by Dr. Cadmium
ilyaz wrote:
The question is whether I can assume that a magnetron is functional if it passed both tests described in steps 4 and 5.

Thanks.


Yes.

But - I would not sell a used magnetron or capacitor from any household countertop microwave that's more than a few years old. Most modern consumer level microwaves are really cheap to buy new.

Commercial microwaves and more expensive under-the-counter models are a totally different story. Many businesses run older equipment and would rather buy a few used parts then new equipment.

Usually when a microwave is dumped curbside there's only one thing wrong with it. Exceptions are if it was dropped, set on fire or hit by a large power surge - the first two being obvious by visual inspection. If you can diagnose the problem, you can usually assume the other components are good.

Re: Slightly OT: how to test magnetrons?

PostPosted: Mon Feb 07, 2011 10:31 pm
by ilyaz
Dr.

So are you saying that it's unlikely anybody will buy even a slightly used but functional magnetron from a consumer-grade oven, but other components might be more valuable?

I have two yards not too far from me: one does not take magnetrons at all, the other takes it as light iron. So I guess microwaves turned out to be much less valuable as scrap than I thought originally. Oh well...

Re: Slightly OT: how to test magnetrons?

PostPosted: Tue Feb 08, 2011 10:34 am
by Dr. Cadmium
It's my opinion that's it's not worth my time to deal with older parts from cheaper appliances. I can't say what the best approach is for someone else.

When in doubt, look online and see if anyone else is selling that particular model part. See what they're asking and what others have sold for.

If a part is relatively modern and no one else has one available, you can in theory charge whatever you want for it. Just make sure it's a savings over buying a whole new microwave. It makes sense to charge $25-$30 for a used magnetron to fix a two-year-old $120 microwave.

On the other hand, some people stock their online stores full of hundreds to thousands of $5-$10 used parts. That way they keep a steady flow of orders coming in every week. Even though they're only making a few dollars profit per item, it adds up.

The glass cooking tray that most scrappers throw away is actually the easiest and most profitable part of a used microwave to sell. This is the part that people always break and need to replace. Also, no testing required. Just make sure you have the correct part number and dimensions and that you know how to package glass items for shipping.

Re: Slightly OT: how to test magnetrons?

PostPosted: Tue Feb 08, 2011 11:16 am
by ilyaz
Dr. Cadmium wrote:The glass cooking tray that most scrappers throw away is actually the easiest and most profitable part of a used microwave to sell. This is the part that people always break and need to replace. Also, no testing required. Just make sure you have the correct part number and dimensions and that you know how to package glass items for shipping.


Thanks, this is a great suggestions!

Re: Slightly OT: how to test magnetrons?

PostPosted: Tue Feb 08, 2011 12:15 pm
by natsb88
ilyaz wrote:
Dr. Cadmium wrote:The glass cooking tray that most scrappers throw away is actually the easiest and most profitable part of a used microwave to sell. This is the part that people always break and need to replace. Also, no testing required. Just make sure you have the correct part number and dimensions and that you know how to package glass items for shipping.


Thanks, this is a great suggestions!

When our microwave died a couple years ago, I listed the glass turntable on eBay and got something like $35 for it :D

Re: Slightly OT: how to test magnetrons?

PostPosted: Sat Feb 12, 2011 12:49 am
by cuppoor
ilyaz wrote:
cuppoor wrote:If you are not an electrician or a EE then I would recommend not trying to test them. The autotransformer and rectifier produce lethal high voltage and current and doubly dangerous since it's not isolated from line voltage. If you don't have the knowledge and proper test equipment then don't try it. It's not worth it.


All the magnetrons I am trying to test have already been pulled out of the microwaves, so there is no danger of electric shock.

I found the following page on testing magnetrons: http://www.ehow.com/how_5864880_test-magnetron-microwave-oven.html

The question is whether I can assume that a magnetron is functional if it passed both tests described in steps 4 and 5.

Thanks.


Okay you are testing the resistance of the magnetron for shorts after safely discharging the cap. That's a pretty good test but you may not be 100% sure it still works under proper load. Still be cautious though as your provided link is a little vague on getting the cap and mag out of the oven. It should be discharged first before doing anything after power is removed. Once its out don't plug it in unless you want to make dangerous voltages or fry something nearby. Anytime those caps are re-energized they can keep lethal charges for a long time, just like CRTs.