24 replies to this topic

[ibis81]

When I use my Advantium microwave function for a minute or so it begins to emit a burning electrical smell. It seems to come out the exhaust under the microwave. Any idea on how to troubleshoot?

[Samurai Appliance Repair Man]

Hard to troubleshoot a smell. About the best you could do is to open her up and have a look at the guts, looking forward discoloration, scorching, and paying particular attention to any burned solder joints on the back of the circuit board.

[ibis81]

I had opened it and checked everything. It all looked ok so I put it back together. Fast forward six months and I now have a dead advantium. I opened it up again and the line fuse holder is melted on the bottom half.

I have read that a fault by one of the latch sensors will cause the line fuse to be intentionally shorted. Is that correct? If so, would it melt the holder? Should I start with those or are there other trouble shooting steps I should take first.

[RegUS_PatOff]

... have read that a fault by one of the latch sensors will cause the line fuse to be intentionally shorted.

... Fuse would blow instanly ..
wouldn't cause an "electrical burning smell"
For service manuals and other perks,
http://appliantology...-special-perks/

[ibis81]

... Fuse would blow instanly ..
wouldn't cause an "electrical burning smell"
For service manuals and other perks,
http://appliantology...-special-perks/

Thanks for the quick response. Any other guidance on where to start?

I will check out the membership when I get home.

[RegUS_PatOff]

could be a bad HV Diode, HV Capacitor or bad Magnetron
31-9038
link PM'd

[ibis81]

Ok. I suspect the smell was caused by the melting plastic fuse holder.

I did a visual inspection of the diode and capacitor. Both show no signs of any problem. I'll check them with an ohmmeter tomorrow.

Any idea where I can find instructions on testing the magnetron?

[RegUS_PatOff]

... did a visual inspection of the diode and capacitor. Both show no signs of any problem.

if bad, they won't show any visual indications

[ibis81]

So I tested the diode and the capacitor. It looks like the capacitor is ok but the diode seems to be faulty. At least thats what my very rusty multimeter skills indicate. The when I test the cap in one direction it reads infinity. When I switch it it reads negative and then returns to infinity. I think that is what it's supposed to do. Please confirm.

The diode shows infinity in both directions.

If it is the diode should I check anything else that would have made it fail?

Also should I also check the magnetron? If so how do I do that?

Edited by ibis81, 17 September 2011 - 04:17 PM.

[RegUS_PatOff]

... reads negative and then returns to infinity.
... he diode shows infinity in both directions.

1) yes
2) Diode is probably OK, usually shorts when bad.
use a 9v battery in series and test for voltage
forward = some voltage
reverse = 0 v

[ibis81]

Yep. Sure enough the diode shows voltage in only one direction.

I found some instruction on testing the magnetron. It reads ~.9-1 ohm across the terminals.

[Samurai Appliance Repair Man]

Only thing left is the HV transformer. Test the primary and secondary windings. Look for discoloration around it, too.

[Budget Appliance Repair]

Disconnect the two wires going to the magtube and set it for 20-30 seconds and run it. If no abnormal noises and no smell with magtube disconnected, (MAKE SURE BOTH WIRES THAT ARE DISCONNECTED FROM THE MAGTUBE ARE SAFELY AWAY FROM EVERYTHING AND MAKE SURE NOT TO GET NEAR THEM!!!!!!!), the most likely problem is a bad magtube.

If you short the capacitor, carefully with an insulated screwdriver after doing the above test and it sparks you can be pretty sure
the magtube is bad also.

If everything else checks OK and the smell is kind of a sweet plastic burning smell, (I don't know how else to explain it but once you've smell it once you will know for sure the next time), then it's for sure a bad magtube.

[ibis81]

I tested the hv transformer. These are the results.

Between primary leads -1.2 ohms
Between filament leads - 1.2 ohms
Between tap and chassis - 65 ohms
between filaments and chassis - infinite

Disconnect the two wires going to the magtube and set it for 20-30 seconds and run it. If no abnormal noises and no smell with magtube disconnected, (MAKE SURE BOTH WIRES THAT ARE DISCONNECTED FROM THE MAGTUBE ARE SAFELY AWAY FROM EVERYTHING AND MAKE SURE NOT TO GET NEAR THEM!!!!!!!), the most likely problem is a bad magtube.

If you short the capacitor, carefully with an insulated screwdriver after doing the above test and it sparks you can be pretty sure
the magtube is bad also.

If everything else checks OK and the smell is kind of a sweet plastic burning smell, (I don't know how else to explain it but once you've smell it once you will know for sure the next time), then it's for sure a bad magtube.

I can't do this because the line fuse has blown. I'm afraid if I replace it to test this it will just blow again.

[RegUS_PatOff]

... I can't do this because the line fuse has blown.
I'm afraid if I replace it to test this it will just blow again.

[ibis81]

Ok I'll pick those up. Do the results of the hv transformer tests seem correct? Another site I saw said the readings on the filaments and the primaries should be significantly below one ohm.

[RegUS_PatOff]

... the readings on the filaments and the primaries should be significantly below one ohm.

yes, as shown in the 31-9038 service manual

[ibis81]

yes, as shown in the 31-9038 service manual

I guess what I am asking is what are acceptable tolerances?

In you opinion are the readings I took significantly different to indicate a problem that would cause the original problem?

Should I go ahead and perform the test BAR suggested anyway?

[RegUS_PatOff]

... are the readings I took significantly different to indicate a problem
... Should I go ahead and perform the test BAR suggested anyway?

1) may depend on your meter..
2) that may be the easiest ..

[ibis81]

So i did the test outlined. I ran the microwave with the magnitron disconnected. Everything seemed to run fine.

After I did the test. I unplugged everything. When I shorted the capacitor it did not appear to have held a charge, nothing at all. Is there anything that could account for that?