repair microwave ovan

I have a Panasonic NN-GS597M microwave. When using its microwave heating function, it stops after 4 seconds regardless of the setting is H/M/L. In this 4 seconds, there is a slight "tic tic" sound near the a/c rectifier and the large transformer of the inverter (they seat close to each other). I managed to find an inverter board and replaced it, but didn't solve the problem. So it must be something else that cause the problem.

The rectifier board is just simple R, C, varistor and self recovering fuse, which are unlikely to have any problem. For magnetron, I've measured the resistance of the 2 leads. With my DMM at 200ohm it reads 0.3. Each lead is open to the case of the ovan. So I think the magnetron is ok. So what else can I check to resolve the problem. Please help.

NB. http://www.repairfaq.org/sam/micfaq.htm is where I learn the above, in case it can help others.

 

[sender jones]

One more point, during this 4 seconds, the ovan is noisy as usual. But after it failed, it is quiet but the cooling fan is still turning.

 

[c4urs11]

On Sat, 07 Feb 2015 16:48:25 -0800, sender jones wrote:

One more point, during this 4 seconds, the ovan is noisy as usual.
But after it failed, it is quiet but the cooling fan is still turning.

Can this help, disregarding its fun typos?
http://ask.metafilter.com/259488/Possessed-mircowave


Cheers!

 

[Samuel M. Goldwasser]

sender jones <senderj@hotmail.com> writes:

One more point, during this 4 seconds, the ovan is noisy as usual. But
after it failed, it is quiet but the cooling fan is still turning.

There isn't much besides the rectifier, inverter, and magnetron.

That tick tick might be the inverter trying to power an excessive load -
just a guess.

Magnetrons can fail with voltage applied and test good on a meter.

You can probably find a new/NOS replacement for less than $20 on eBay.

It's worth the risk.

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[sender jones]

On Sunday, February 8, 2015 at 8:32:59 AM UTC+8, sender jones wrote:

I have a Panasonic NN-GS597M microwave. When using its microwave heating function, it stops after 4 seconds regardless of the setting is H/M/L. In this 4 seconds, there is a slight "tic tic" sound near the a/c rectifier and the large transformer of the inverter (they seat close to each other). I managed to find an inverter board and replaced it, but didn't solve the problem. So it must be something else that cause the problem.

The rectifier board is just simple R, C, varistor and self recovering fuse, which are unlikely to have any problem. For magnetron, I've measured the resistance of the 2 leads. With my DMM at 200ohm it reads 0.3. Each lead is open to the case of the ovan. So I think the magnetron is ok. So what else can I check to resolve the problem. Please help.

NB. http://www.repairfaq.org/sam/micfaq.htm is where I learn the above, in case it can help others.

Thank you for all the replies. I finally get hold of a replacement magnetron. But there is a scratch mark on the insulator of the emitting end.

https://kanbox.com/a/zE7nqe

Are modern domestic microwave ovens still use beryllium oxide in their magnetron insulator. I know beryllium is highly toxic. But will such scratch mark dangerous?