microwave buzing/humming confirm suspicions

[torxhead]

hi just a quick post.
my miscrowave is buzzing/humming loud.
i suspect the transformer.
can anyone confirm my suspcions,
t.i.a.

[A1TEC]

Re: microwave buzing/humming confirm suspicions

Could be magnatron. 😉

[chezza]

Re: microwave buzing/humming confirm suspicions

check diode and capacitor too 😆

transformers not usualy too much trouble

[torxhead]

Re: microwave buzing/humming confirm suspicions

update.
hi thanks for replies.
magnetron is lighting up, but i dont know how much it should glow.
ideas anyone?
i suspect the magnetron but would like a second opinion.

[Phidom]

Re: microwave buzing/humming confirm suspicions

As the magnetron is a type of thermionic valve there is not much you can check on it with the meter, apart from the heater filament, which rarely fails. You therefore have to use the Sherlock method and eliminate everything else, leaving just the magnetron. You can check the capacitor, which will get charged by the multimeter battery and show increasing resistance until it goes to infinity. You can also check the primary and secondary resistances on the transformer. The diode will normally read open circuit in both directions on a normal multimeter but you can still check for shorts. There may also be a short circuit protection diode which can ironically also go short circuit. If the other parts check out OK you can be pretty certain the magnetron is cream crackered. On the other hand, if it’s an inverter type machine, that’s a whole different ball game!

[torxhead]

Re: microwave buzing/humming confirm suspicions

how can you tell if it is an inverter machine from the internals? is it the same set up, ie transformer, capacitor, magnetron?

[Phidom]

Re: microwave buzing/humming confirm suspicions

No, I was probably confusing the issue there. The inverter microwaves don’t have the big capacitor and the magnetron wires go to a circuit board mounted in the base of the machine.

[torxhead]

Re: microwave buzing/humming confirm suspicions

hi, well thats new to me.
ive never heard of an invertor microwave, but lets not go into it.

thanks for the reply anyway, it helps me think. :rolls:

[eastlmark]

Re: microwave buzing/humming confirm suspicions

Phidom wrote:No, I was probably confusing the issue there. The inverter microwaves don’t have the big capacitor and the magnetron wires go to a circuit board mounted in the base of the machine.

more obviously…..they dont have a transformer and the wieght associated with it.

Torxhead, please do not start new threads on the same subject. AFAICT there are 3 threads running on this same issue.

[clivejameson]

Re: microwave buzing/humming confirm suspicions

torxhead wrote:
ive never heard of an invertor microwave, but lets not go into it.

I just hope you’re well insured 😀

[torxhead]

Re: microwave buzing/humming confirm suspicions

its funny, im getting all these emails which arent relatiing to my original post, and yet no one has been agble to give me any anwsers which i had hoped for.

a bit dissapointed on this occasion with the response.

[clivejameson]

Re: microwave buzing/humming confirm suspicions

Well Torxhead, you are obviously learning on the job, inverters have been about for at least ten years now. Inverters are electronic circuit boards that provide the necessary high voltage to the magnetron, they are fairly reliable, lighter in weight than a transformer and far more expensive (to the end user). They are nearly always unrepairable when faulty mainly due to the fact that manufacturers don’t provide detailed technical information and testing the high voltages produced without the correct equipment is lethal (literally).
To answer your question directly without the ear of experience to hear the noise, the only pragmatic way way to test for this fault is to substitute a known good magnetron.
Sorry to sound harsh on this but it’s out of concern for your safety, if you are already measuring voltages on the magnetron you are putting yourself in grave danger if you do not have the correct measuring equipment and use safe working practices…..

[torxhead]

Re: microwave buzing/humming confirm suspicions

hi, i appreciate your concerns and info on the inverters.
but i am not new to working with electrical or electronic devices, as i have done since the age of 16 when i gained my city and guilds 224 part one and two.

i am aware of the capacitor holding charge which has to be discharged my means of shorting both the terminals with an insulated instrument.

there is nothing wrong with measuring the two wires to the magnetron for voltage, as this is common practice.

this post isnt getting anywhere, i will try a different thread which will help me come to a conclusion. or find some other opinions to confirm my suspicions.

i need to know if magnetrons are interchangeable. because the price of a magnetron for my machine is £110 each and there are two of them.

i am making all the effort to find the fault without guessing and putting new parts on to see if it works.

that sort of procedure is not all that reliable, especially if you have an intermittent fault or a faulty new part.

[torxhead]

Re: microwave buzing/humming confirm suspicions

fao eastlmark moderator.

i have more than one microwave both the same model, both with different issues.

one thread was for one fault i have with micro a

the other thread was for the fault reported with micro b

if you wish, clear/lock the threads, as i have progressed a bit more.

i have started another thread with a different question about microwaves in general.
cheers

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