On 15/05/2021 22:26, Max Demian wrote:
On 15/05/2021 18:09, Tim+ wrote:
Chris Bacon wrote:
On 15/05/2021 05:59, jon wrote:

So any help on what's up, and what to do about it?

I had something similar and it turned out to be the magnetron breaking
down under load.

I've got one on order, plus 10 fuses....

I didnt realise it was economically viable to replace magnetrons.Â* I
must
admit, if our ancient Panasonic ever dies (about 35 years old), if
possible
I would like it repaired as it has a €œproper€� mechanical countdown timer
and a real bell that goes €œding€�. ;-)

I don't think it would be economical to replace the glass turntable on
mine as I think they charge £25 including carriage and the oven cost £40.

In case I break it, I've lifted the turntable from one someone threw out.


The secondary metal tray that comes with a Panny combi micro (which you
must use on top of the glass turntable when using grill or convection
oven) was missing from my BHF charity shop purchase so I use the old
enamelled metal turntable from my defunct Sharp. It's the same diameter
so just sits on top. They are about £44 to buy :-(. I only paid £30
for the oven.

On 16/05/2021 08:37, Chris Bacon wrote:
On 16/05/2021 08:21, Jeff Layman wrote:
Why is the turntable made from glass, and not the same metal as the
rest of the microwave oven? Glass is pretty transparent to microwave
frequencies, and the turntable is only a cm or so above the metal
floor, so why not make the turntable from the same metal?

Yes, that. Mine's a steel one. There's a resistive heating element
under, which allows the turntable to be used to make nice pizzas in!

Really. That is what the Sharp microwaves had, plus a halogen grill
at the top, allowing it to get up to convection temp (even up to 230C)
in minutes.

No-one seems to make them like that now, so I'm not surprised you
are repairing yours. My Sharp is sitting in my car waiting for its
trip to the dump, even though the grill and oven part work fine,
only the microwave bit is dead.

On 16/05/2021 11:00, newshound wrote:
On 15/05/2021 23:29, The Natural Philosopher wrote:
On 15/05/2021 18:09, Tim+ wrote:
I must
admit, if our ancient Panasonic ever dies (about 35 years old), if
possible
I would like it repaired as it has a €œproper€� mechanical countdown timer
and a real bell that goes €œding€�.;-)

So does my brand new 'catering' microwave.

And the 45? quid cheapo from Tesco that it replaced


While I am all for repair in general, IMHO the functionality of
"expensive" microwaves (oven, grill, etc) is a waste of time. I think I
replaced a fuse in one once, but they are a minefield even for
experienced repairers unless you actually have a background in them. So
I with TNP here, throw it away and replace with a £50 or less basic. It
will go in the "metals" skip at the tip so the steel, stainless steel,
and copper will all get recovered and recycled. I don't believe there
will be enough on the PCB to be worth recovering, but perhaps as robots
get smarter they will get plucked out before shredding too.

He threw away a £45 Tesco cheapee and replaced it with a commercial
microwave, but they tend to be too big for most domestic settings
and usage.

On 16/05/2021 13:20, Andrew wrote:
On 16/05/2021 11:00, newshound wrote:
On 15/05/2021 23:29, The Natural Philosopher wrote:
On 15/05/2021 18:09, Tim+ wrote:
I must
admit, if our ancient Panasonic ever dies (about 35 years old), if
possible
I would like it repaired as it has a €œproper€� mechanical countdown
timer
and a real bell that goes €œding€�.;-)

So does my brand new 'catering' microwave.

And the 45? quid cheapo from Tesco that it replaced


While I am all for repair in general, IMHO the functionality of
"expensive" microwaves (oven, grill, etc) is a waste of time. I think
I replaced a fuse in one once, but they are a minefield even for
experienced repairers unless you actually have a background in them.
So I with TNP here, throw it away and replace with a £50 or less
basic. It will go in the "metals" skip at the tip so the steel,
stainless steel, and copper will all get recovered and recycled. I
don't believe there will be enough on the PCB to be worth recovering,
but perhaps as robots get smarter they will get plucked out before
shredding too.

He threw away a £45 Tesco cheapee and replaced it with a commercial
microwave, but they tend to be too big for most domestic settings
and usage.

OK sorry, I mis-followed the threads. But that's my view, some things
are not actually worth fixing, especially if they are recycled
appropriately.

On 16/05/2021 13:16, Andrew wrote:
On 16/05/2021 08:37, Chris Bacon wrote:
Mine's a steel (turntable). There's a resistive heating element
under, which allows the turntable to be used to make nice pizzas in!

Really. That is what the Sharp microwaves had, plus a halogen grill
at the top, allowing it to get up to convection temp (even up to 230C)
in minutes.

No-one seems to make them like that now, so I'm not surprised you
are repairing yours. My Sharp is sitting in my car waiting for its
trip to the dump, even though the grill and oven part work fine,
only the microwave bit is dead.

That's it. Mine has a grill at the top too. I have done whole roasted
chicken in there before, as well as home-made pizza, it's excellent, and
yes that is one reason I am trying to fix it. I can't remember, but did
you try fixing yours?

On 16/05/2021 13:06, Andrew wrote:
How do Panasonic inverter microwaves work then ?.

My trusty, reliable Sharp just pulsed on and off in varying times
when a power setting less than 100% was chosen, but the Panny sounds
the same om Medium as it does on full power.


Linear power control, no pulsing.

It's a variant of SMPS, the transformer is physically smaller etc....

Panasonic normally make domestic goods and electronics that last a good
years with abuse. Their microwave ovens are fine, have a good bit of
space inside. However, they don't last - we've sent three of basically
the same model to the skip in twenty years.

Kept all the glass turntables though.

--
Adrian C

Andrew wrote:
How do Panasonic inverter microwaves work then ?.

My trusty, reliable Sharp just pulsed on and off in varying times
when a power setting less than 100% was chosen, but the Panny sounds
the same om Medium as it does on full power.

Andrew

You can see a sample schematic here. AC to DC to AC to DC.

https://fccid.io/ACLAP4T01/Schematic...atic-77643.pdf

T701 is the output transformer.


On 15/05/2021 08:57, Brian Gaff (Sofa) wrote:
There is no such thing as low power on a Magnetron, they simply put it on
and off to simulate the lower energy over time so to speak.

Is the filament reading OK?

Also, I was intrigued by the diode being such a poor conductor in one
direction, in your previous post. However as you have not actually killed
yourself yet, my guess is there is no eht for whatever reason.
Brian

On 16/05/2021 17:08, Chris Bacon wrote:
On 16/05/2021 13:16, Andrew wrote:
On 16/05/2021 08:37, Chris Bacon wrote:
Mine's a steel (turntable). There's a resistive heating element
under, which allows the turntable to be used to make nice pizzas in!

Really. That is what the Sharp microwaves had, plus a halogen grill
at the top, allowing it to get up to convection temp (even up to 230C)
in minutes.

No-one seems to make them like that now, so I'm not surprised you
are repairing yours. My Sharp is sitting in my car waiting for its
trip to the dump, even though the grill and oven part work fine,
only the microwave bit is dead.

That's it. Mine has a grill at the top too. I have done whole roasted
chicken in there before, as well as home-made pizza, it's excellent, and
yes that is one reason I am trying to fix it. I can't remember, but did
you try fixing yours?

Mo, I don't really have the courage to poke about too carefully and
it weighs about 21 KG so it is a bit of a lump to manouvre.

If the 2nd hand panny lasts a year I haven't lost anything, it was
only £30. Actually, considering it only has the halogen top element
for grill and oven it gets up to temp acceptably fast. I only use
it up to 190C and I don't do Pizzas.

On 14/05/2021 13:31, Chris Bacon wrote:
So it was making an odd noise, and not heating the food, light comes on,
steel turntable revolves, beeper sounds at end of cook time.

Check HV fuse. Blown. Aha, replaced, it's done that before, should be
OK... but no! Food still cold, fuse blown again.


Check the diode (CL04-12) using a multimeter on 20V setting and 9V
(actually 8.34V) battery. 0V one way, 3.26 the other. A bit low?

Capacitor: No connection (meter on 2000k ohms setting) between either
terminal and case. Between terminals resistance increases from zero to
infinity over a second or so.

Magnetron: Meter set to 200 ohms. 0.5 ohms between terminals either way.
Meter set to 2000kohms, no connection between terminals and case.

High voltage transformer: Primary, isolated, about 2.2 ohms. Secondary
150. There is another winding that seems to go to the magnetron, I don't
know what this is.


So any help on what's up, and what to do about it?

I came across this link and thought of this thread.

It shows the diode and capacitor arrangement clearly and typical of a
mains transformer (non-inverter) circuit.
http://www.kronjäger.de/hv-old/hv/where/micro.html

On 18/05/2021 12:48, Fredxx wrote:
I came across this link and thought of this thread.

It shows the diode and capacitor arrangement clearly and typical of a
mains transformer (non-inverter) circuit.
http://www.kronjäger.de/hv-old/hv/where/micro.html
That's nice. My fuses arrived tody, in a jiffy bag with two unfranked
1st. class stamps on, too. I'm still a little worried about the state of
my diode

On 14/05/2021 13:31, Chris Bacon wrote:
So it was making an odd noise, and not heating the food, light comes on,
steel turntable revolves, beeper sounds at end of cook time.

Check HV fuse. Blown. Aha, replaced, it's done that before, should be
OK... but no! Food still cold, fuse blown again.


Check the diode (CL04-12) using a multimeter on 20V setting and 9V
(actually 8.34V) battery. 0V one way, 3.26 the other. A bit low?

Capacitor: No connection (meter on 2000k ohms setting) between either
terminal and case. Between terminals resistance increases from zero to
infinity over a second or so.

Magnetron: Meter set to 200 ohms. 0.5 ohms between terminals either way.
Meter set to 2000kohms, no connection between terminals and case.

High voltage transformer: Primary, isolated, about 2.2 ohms. Secondary
150. There is another winding that seems to go to the magnetron, I don't
know what this is.


So any help on what's up, and what to do about it?

Well, I fitter a used magnetron sourced from
appliancespareparts.mysimplestore.com, with some worry, because it
looked as if it had been wrenched from some machine and thrown into a
parts bit with lots of others. Anyway, straightened out where possible,
fitted, bits put back together, replaced the fuse and it works. Yay!
Success! What was cold can now easily be made hot again.

The "headline" part number "M24FB-610A GALANZ MICROWAVE MAGNETRON" is
the same on both the original and replacement, but the business ends of
the things, have differently shaped holes, presumably something to do
with how they're put together during manufacture, I can't see anything
that says the hole shape has anything to do with functionality.

On 18/05/2021 14:19, Chris Bacon wrote:
On 18/05/2021 12:48, Fredxx wrote:
I came across this link and thought of this thread.

It shows the diode and capacitor arrangement clearly and typical of a
mains transformer (non-inverter) circuit.
Â*Â*Â* http://www.kronjäger.de/hv-old/hv/where/micro.html
That's nice. My fuses arrived tody, in a jiffy bag with two unfranked
1st. class stamps on, too. I'm still a little worried about the state of
my diode

Is that the one on your left side?

:-)

On 20/05/2021 22:34, newshound wrote:
On 18/05/2021 14:19, Chris Bacon wrote:
I'm still a little worried about the state of my diode

Is that the one on your left side?

No, it's OK in fact. I used the microwave to warm up my tea. But now I
have no tea.

On Thu, 20 May 2021 22:34:19 +0100, newshound
wrote:

I'm still a little worried about the state of
my diode

Is that the one on your left side?

:-)

I got it mate. ;-)

Cheers, T i m