microwave magnetron dead?


no shorts between magnetron contacts or ground but when plugged it does not heat the oven contents and has loud hum Is it dead(how to make sure) or perhaps requires say 1v higher cathode heating voltage than what transformer supplies?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

This is tube that came with a microwave oven, and the tranformer that came with it too?
Did it used to work?
I think it unlikely that it requires a mere 1 volt more voltage, or that the working transformer doesn't provide the right voltage. The transformer may be the most expensive part ot replace.
Be careful running the thing with the cover off. I presume there is still a shield around the microwave tube, but if so, absolutely don't run the thing without the shield. Radio Shack used to sell inexpensive (10$) microwave detectors, for testing leakage around microwave ovens. Maybe they still sell them. I know that mine worked well, because I had an overn without a latch, and by pulling the door open a little, I was able to watch the meter reading rise from very very low to quite a bit higher.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Loud hum sometimes means something is shorted. The increased load on the transformer makes it hum more. You can't always detect a short in a high voltage component with an ohm meter. You can measure the heating element voltage with an multi-meter but you really ned to be careful. There is probably a diode and capacitor in the high voltage circuit as well. If the diode has shorted the ac load will go through the capacitor and that can also cause the high hum. I tried to fix one once that had a bad magnitron but the magnitron was about half the cost of a whole new microwave,
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Do you have experience with high voltage and RF equipment, especially microwave/radar frequencies? Do you have the equipment for measuring high voltage safely? You need something that can handle 10,000 volts - a cheap Radio Shack meter will not do this safely. By the questions you ask, I'm guessing you don't.
I very strongly recommend that you close up the cabinet and either take it to someone that knows what they are doing, or throw it in the trash. Microwave ovens are incredibly dangerous if you don't know what you are doing, and you can end up seriously injured or dead real fast. It's not worth it - just throw it in the trash.
If you really want to try to fix it and risk killing yourself and burning down your house, etc. :-)
Try here; http://www.gallawa.com/microtech /
It has some basic service procedures, but I don't think you will find anything telling you how to troubleshoot the RF or high voltage circuitry. That requires special knowledge and equipment that not even a lot of the techs that fix these things have.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Could be a lot of things most are unsafe to test without proper equipment and experience. The voltages exceed that which can be safely handled by most voltmeters. Back when I used to work on these things the first things I would check is the diode, filament caps, power supply cap. I could do this safely with ohm meter and Hi-pot tester. I had a homebrew test bed for checking transformers, don't even think of measuring voltage on these even the filament are at multi kilovolt levels and grounded to the chassis. The decision to replace the maggie was usually based on a process of elimination.
Jimmie
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I ran into that recently. It sort of started to work by generating heat, but that didn't last long. I like using an old analog meter with the 5 KV scales. I didn't get a chance to replace the manetron. It cost the owner a bunch for the transformer and diode.
The diode and transformer became BAD, but don't know at what point. Before or after the manetron went bad. greg
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
abo mahab wrote:

I see you're posting from 93.98.28.228, which works out to be
IP address: 93.98.28.228 Reverse DNS: [No reverse DNS entry per ns-pri.ripe.net.] Reverse DNS authenticity: [Unknown] ASN: 34397 ASN Name: CYBERIA-RUH (Cyberia Riyadh Autonomous System) IP range connectivity: 2 Registrar (per ASN): RIPE Country (per IP registrar): SA [Saudi Arabia] Country Currency: SAR [Saudi Arabia Riyals] Country IP Range: 93.98.0.0 to 93.98.255.255 Country fraud profile: Normal City (per outside source): Riyadh, Ar Riyad Country (per outside source): SA [Saudi Arabia] Private (internal) IP? No IP address registrar: whois.arin.net
Whatsa matter? Couldn't find anyone in your country interested in listening to you?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
mynick wrote:

Watch out for a big capacitor in there which in some cases can give you a nasty high voltage bite even after the oven has been unplugged for a while.
Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat \'57 EE)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
In article

Or as a guy I know would so eloquently warn... "Dont ya'll be messin with that s**t lest you know what you doin; it'll up'n give yo ass a dirt nap"
Good advise too. I hate 'dirt naps' anymore, especially now that I'm a bit older.
Microwaves reached disposable appliance status eons ago... if it's not in warranty, spring for a new one, they're cheap.
Erik
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I meant what is going to happen if you try replace original magnetron with one that has 4.13v or 3.6v filament voltage but original hv transformer gives 3.15V
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Video Please, I want to see this on stupid microwave tricks.
Jimmie
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Those numbers don't seem to make any sense at all. Sounds like maybe something is shorted or the capacitor or rectifier is shot.
BE VERY, VERY CAREFUL. LETHAL VOLTAGES!!!!!!!.
My advice is always, don't mess with it unless you are a competent high voltage/radio transmitter technician! There are voltages of 5000+ volts and potential RF radiation that can fry your eyes (cos that's what it does in minutes to meat, eh?). In effect a m.wave oven is a one kilowatt radio transmitter in a tin box! And much less than that can easily kill you!!!!!!!!
The circuit is complex enough that the typical do it yourself-er may not be able to follow. For example we recently fixed, in less than 20 minutes, a microwave that the owner, a capable sort of chap for most 'carpentry type' repairs, but not an electronics technician, thought had a bad component in the power supply (HV transformer, rectifier, capacitor etc.) .
Then he thought it was something to do with the control panel!
Initially I had thought it might be the contacts of the relay on the control panel that switches most of the power the m.wave uses. One could hear it closing but no power!
It wasn't any of those! The problem was a defective door micro-switch (Canadian Spec. not necessarily same as USA by the way!) that prevented basic 115 volts AC from reaching the fan, the power supply, the interior light etc. etc. A somewhat basic fault as it turned out. We had a spare micro-switch of the same spec. from a junked m.wave fairly easy install, stand back, since the cover was still off, for a test and it was all done.
Not only the wrong diagnosis, twice, plus my first thought about the control realy; but the owner had put the cover back on incorrectly and it had a slight gap where microwaves 'might' be able to leak right near the door 'handle'! Not good.
For goodness sake 'BE CAREFUL' a replacement m.wave can be had for around $50 and the risk is not worth it.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I was checking out an amplifier I built and broke, and sitting for a couple years. Sure enough, I got a spark messing around with it.
greg
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Oct 16, 6:14am, snipped-for-privacy@zekfrivolous.com (GregS) wrote:

If the filament voltage->current is too low maybe it will not emmit,why else is that magnetron spec?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
mynick wrote:

Hi, More than magnetron. Suspect your HV source.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
mynick wrote:

Sounds like it maybe the HV-Diode..
P.S. You most likely won't be able to test it with your DMM unless it's totally shorted.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
responding to http://www.homeownershub.com/maintenance/microwave-magnetron-dead-400476-.htm lawei wrote:
mynick wrote:

-------------------------------------
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.