Glowing Magnetron.

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Panasonic Inverter microwave oven model NN-S751WF.
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Fault - Oven starts to cook but soon shuts off.

Customer told me one of his children turned the oven on for several
minutes with nothing in it.
The magnetron was a bit bent out of shape.

After testing the oven with a secondhand Magnetron,
and finding everything to work o.k., I bought a new 2M261-M32 from
WES.

The oven does work with the new Magnetron, but there is a red glow in
the top
near the terminals that concerns me. There is no glow from the
secondhand unit.


Could the new unit be faulty?



Thanks in advance,
Russell Griffiths.

 

[Jeff]

Hi Russell ,
I will let you know of my experiences with microwave repairing.
Firstly I will assume you know all the safety stuff about the HV

I have safely been able to measure the filament/heater winding - which is
around 3v (extreme caution needed as it is above 2kv)
Luckily I haven't had to do this very often due to the risk.
I have gone by a very simple and maybe crude way of listening to the magie
at switch on and the overall temp after running it for a set time.
"Most" magies will give a noticeable increase in loading within the first 2
seconds (as the filament/heater warms up)
and after 1 min heating a cup of water the magie will be less than 50 deg
(warm but not hot)
Due to the replacement cost of most mw's I haven't seen many lately - so I
cannot confirm the heater as visible, all the ones that I have seen to date
are enclosed and not visible at all.
But due to the HV and current if there was an issue with the terminals and
insulation etc - it WILL become very noticeable very quickly.

my 2 cents worth anyway
Jeff

 

[Mitch]

Hi Russell ,
I will let you know of my experiences with microwave repairing.
Firstly I will assume you know all the safety stuff about the HV

I have safely been able to measure the filament/heater winding - which is
around 3v (extreme caution needed as it is above 2kv)
Luckily I haven't had to do this very often due to the risk.
I have gone by a very simple and maybe crude way of listening to the magie
at switch on and the overall temp after running it for a set time.
"Most" magies will give a noticeable increase in loading within the first
2 seconds (as the filament/heater warms up)
and after 1 min heating a cup of water the magie will be less than 50 deg
(warm but not hot)
Due to the replacement cost of most mw's I haven't seen many lately - so I
cannot confirm the heater as visible, all the ones that I have seen to
date are enclosed and not visible at all.
But due to the HV and current if there was an issue with the terminals and
insulation etc - it WILL become very noticeable very quickly.

my 2 cents worth anyway
Jeff

Russel and Jeff,

my two cents worth. when I was repairing them in the late 1980s, I
remember
hearing after pushing the start button. 1. a low level hum. then, 2 a
sizzling sound.then, 3 a much loader hum as the magentron starts
to emit microwaves.

On the subject of caution, the supply in the oven is lethal. A friend in
the 80s showed me, through an experiment, just how lethal they are.

Regards,
Mitch...

 

[Jeff]

I concur Mitch,
My test setup is completely hands and body free (nowhere within 3 feet).

I don't measure the HV much anymore as I do most by ear - and you don't need
to most times

Regards
Jeff