In a classic example of “Sod’s law” when the repair man came around to look
at our 43 year Toshiba it started working perfectly. Made all the normal
humming noises that had been absent before and made stuff hot.

Can magnetron filaments behave like old light bulbs and start working again
if shoogled a bit?

Of course I’m sure it’ll die again soon and given that the repairman didn’t
really have any useful repair suggestions I’m no worse off. Kinda tempted
to attempt a magnetron transplant when it dies. Seems it’s not that hard
if the internet is to be believed…

Tim

--
Please don't feed the trolls

Tim+ <tim.downie@gmail.com> wrote:
>
> In a classic example of “Sod’s law” when the repair man came around to look
> at our 43 year Toshiba it started working perfectly. Made all the normal
> humming noises that had been absent before and made stuff hot.
>
> Can magnetron filaments behave like old light bulbs and start working again
> if shoogled a bit?
>
> Of course I’m sure it’ll die again soon and given that the repairman didn’t
> really have any useful repair suggestions I’m no worse off. Kinda tempted
> to attempt a magnetron transplant when it dies. Seems it’s not that hard
> if the internet is to be believed…
>
> Tim
>

Just a little follow up. I’ve found a magnetron on-line that claims to be a
substitute for mine (a 2M172J).

https://magsells.co.uk/product/magnetron-msm702/

The thing is, this is a 1050 W one and I think our old one was rated at 650
W. Would it be reasonable to assume that fitting this would be a bad idea?

Tim

--
Please don't feed the trolls

On 8/4/2023 6:27 PM, Tim+ wrote:
> Tim+ <tim.downie@gmail.com> wrote:
>>
>> In a classic example of “Sod’s law” when the repair man came around to look
>> at our 43 year Toshiba it started working perfectly. Made all the normal
>> humming noises that had been absent before and made stuff hot.
>>
>> Can magnetron filaments behave like old light bulbs and start working again
>> if shoogled a bit?
>>
>> Of course I’m sure it’ll die again soon and given that the repairman didn’t
>> really have any useful repair suggestions I’m no worse off. Kinda tempted
>> to attempt a magnetron transplant when it dies. Seems it’s not that hard
>> if the internet is to be believed…
>>
>> Tim
>>
>
> Just a little follow up. I’ve found a magnetron on-line that claims to be a
> substitute for mine (a 2M172J).
>
> https://magsells.co.uk/product/magnetron-msm702/
>
> The thing is, this is a 1050 W one and I think our old one was rated at 650
> W. Would it be reasonable to assume that fitting this would be a bad idea?
>
> Tim

Seeing as the diagram for it "looks like a tube", the parametrics
could be quite different. The HV transformer could be putting out
a different voltage level, on the two designs.

Maybe the parametrics of your tube have shifted enough, it will start
some times, and not others.

Paul

On 04/08/2023 22:19, Tim+ wrote:
>
> In a classic example of “Sod’s law” when the repair man came around to look
> at our 43 year Toshiba it started working perfectly. Made all the normal
> humming noises that had been absent before and made stuff hot.

There's nothing like an intermittent fault to drive you round the bend.

Well, if it has been working correctly, then you are now guaranteed to
have the HV capacitor(s) fully charged! If you do go fiddling around
inside, perhaps to change the magnetron, you'll have to be really
careful to make sure any caps are discharged completely.

> Can magnetron filaments behave like old light bulbs and start working again
> if shoogled a bit?

I would very much doubt it.

> Of course I’m sure it’ll die again soon and given that the repairman didn’t
> really have any useful repair suggestions I’m no worse off. Kinda tempted
> to attempt a magnetron transplant when it dies. Seems it’s not that hard
> if the internet is to be believed…

One fairly simple thing to try if the fault's intermittent is to look
for a dry joint. If the circuitry is reasonably straightforward, a few
minutes going over any soldered joints with fresh solder can't harm.

--

Jeff

Door switch trouble?
I have never found a Magnetron to come back to life if it dies. More likely
to be a dodgy connection. Also some silicon rectifiers of the vintage did
have shrinking plastic syndrome where the wire that goes into the body gets
a void around it and eventually the weld to the wire to the device inside
can become intermittent. The only way to know for sure is to swap them out.
Brian

--

--:
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"Tim+" <tim.downie@gmail.com> wrote in message
news:467987403.712876439.015592.tim.downie-gmail.com@news.individual.net...
>
> In a classic example of "Sod's law" when the repair man came around to
> look
> at our 43 year Toshiba it started working perfectly. Made all the normal
> humming noises that had been absent before and made stuff hot.
>
> Can magnetron filaments behave like old light bulbs and start working
> again
> if shoogled a bit?
>
> Of course I'm sure it'll die again soon and given that the repairman didn't
> really have any useful repair suggestions I'm no worse off. Kinda tempted
> to attempt a magnetron transplant when it dies. Seems it's not that hard
> if the internet is to be believed.
>
> Tim
>
> --
> Please don't feed the trolls

I'm not convinced its the magnetron from your descriptions, sounds much more
like a dodgy connection somewhere, be it a relay a switch dry joint or
dodgy rectifier.
Magnetrons tend to fade away, not just stop unless the standing wave
detector finds microwaves coming back exceed a certain tolerable level of
course.
Brian

--

--:
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"Tim+" <tim.downie@gmail.com> wrote in message
news:1379166907.712878341.558705.tim.downie-gmail.com@news.individual.net...
> Tim+ <tim.downie@gmail.com> wrote:
>>
>> In a classic example of "Sod's law" when the repair man came around to
>> look
>> at our 43 year Toshiba it started working perfectly. Made all the normal
>> humming noises that had been absent before and made stuff hot.
>>
>> Can magnetron filaments behave like old light bulbs and start working
>> again
>> if shoogled a bit?
>>
>> Of course I'm sure it'll die again soon and given that the repairman didn't
>> really have any useful repair suggestions I'm no worse off. Kinda
>> tempted
>> to attempt a magnetron transplant when it dies. Seems it's not that hard
>> if the internet is to be believed.
>>
>> Tim
>>
>
> Just a little follow up. I've found a magnetron on-line that claims to be
> a
> substitute for mine (a 2M172J).
>
> https://magsells.co.uk/product/magnetron-msm702/
>
> The thing is, this is a 1050 W one and I think our old one was rated at
> 650
> W. Would it be reasonable to assume that fitting this would be a bad idea?
>
> Tim
>
> --
> Please don't feed the trolls

At that age it will be using leaded solder, so itswise to use the same or it
might make things worse.
Brian

--

--:
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"Jeff Layman" <Jeff@invalid.invalid> wrote in message
news:uakr8c$1lcjb$1@dont-email.me...
> On 04/08/2023 22:19, Tim+ wrote:
>>
>> In a classic example of "Sod's law" when the repair man came around to
>> look
>> at our 43 year Toshiba it started working perfectly. Made all the normal
>> humming noises that had been absent before and made stuff hot.
>
> There's nothing like an intermittent fault to drive you round the bend.
>
> Well, if it has been working correctly, then you are now guaranteed to
> have the HV capacitor(s) fully charged! If you do go fiddling around
> inside, perhaps to change the magnetron, you'll have to be really careful
> to make sure any caps are discharged completely.
>
>> Can magnetron filaments behave like old light bulbs and start working
>> again
>> if shoogled a bit?
>
> I would very much doubt it.
>
>> Of course I'm sure it'll die again soon and given that the repairman didn't
>> really have any useful repair suggestions I'm no worse off. Kinda
>> tempted
>> to attempt a magnetron transplant when it dies. Seems it's not that hard
>> if the internet is to be believed.
>
> One fairly simple thing to try if the fault's intermittent is to look for
> a dry joint. If the circuitry is reasonably straightforward, a few minutes
> going over any soldered joints with fresh solder can't harm.
>
> --
>
> Jeff
>

Of course, Brian, *proper* solder! I've still got a few metres of the
stuff for when it's required.

--

Jeff

On 05/08/2023 11:14, Brian Gaff wrote:
> At that age it will be using leaded solder, so itswise to use the same or it
> might make things worse.
> Brian
>

On Friday, August 4, 2023 at 9:19:49 PM UTC, Tim+ wrote:
> In a classic example of “Sod’s law” when the repair man came around to look
> at our 43 year Toshiba it started working perfectly. Made all the normal
> humming noises that had been absent before and made stuff hot.
>
> Can magnetron filaments behave like old light bulbs and start working again
> if shoogled a bit?
>
> Of course I’m sure it’ll die again soon and given that the repairman didn’t
> really have any useful repair suggestions I’m no worse off. Kinda tempted
> to attempt a magnetron transplant when it dies. Seems it’s not that hard
> if the internet is to be believed…

Should that phrase read "43 year OLD Toshiba"? I'm getting daily use from a Sanyo catering microwave oven of the same vintage (bought second-hand in 1986 when Isle College, Wisbech closed its catering course and sold off all the equipment).

Purely based on this one experience, my feeling is that if the magnetron has been working well for all these years, it's not going to be a magnetron problem now. Each time I've had a problem with my Sanyo, it's turned out to be related to a build up of dirt and/or grease. In one case, the dirt caused a problem with the connection to one of the big, internal fuses but the problems have usually been more of a mechanical nature and always (so far, fingers crossed, touch wood) fixable at home by myself.

Nick
nickodell49@yahoo.ca

On 05/08/2023 11:32, Jeff Layman wrote:
> Of course, Brian, *proper* solder! I've still got a few metres of the
> stuff for when it's required.
>
Its not illegal to sell it, just to use it in manufacturing

Tons for sale everywhere.

The point about lead free is its far harder to get it just right so it
makes a decent joint. Amateurs are allowed to use tin/lead. As are some
critical industries.

--
"What do you think about Gay Marriage?"
"I don't."
"Don't what?"
"Think about Gay Marriage."

Jeff Layman <Jeff@invalid.invalid> wrote:
> On 04/08/2023 22:19, Tim+ wrote:
> >
> > In a classic example of “Sod’s law” when the repair man came around to look
> > at our 43 year Toshiba it started working perfectly. Made all the normal
> > humming noises that had been absent before and made stuff hot.
>
> There's nothing like an intermittent fault to drive you round the bend.
>
> Well, if it has been working correctly, then you are now guaranteed to
> have the HV capacitor(s) fully charged! If you do go fiddling around
> inside, perhaps to change the magnetron, you'll have to be really
> careful to make sure any caps are discharged completely.

This. 2kV DC is no joke... especially due to 0.5*CV^2.

These caps are about 1uF, so about 2 joules of stored energy. At 2kV that
could be a very nasty zap.

> > Can magnetron filaments behave like old light bulbs and start working again
> > if shoogled a bit?
>
> I would very much doubt it.

There is a heater element, which I suppose could do the light bulb thing,
but seems unlikely. It could be insulation breaking down, either in the
magnetron or capacitor.

> One fairly simple thing to try if the fault's intermittent is to look
> for a dry joint. If the circuitry is reasonably straightforward, a few
> minutes going over any soldered joints with fresh solder can't harm.

Could be that too, although I wonder how it's managed to have a dry joint
after 43 years. Could be cracking of joints from thermal expansion I
suppose.

Theo

Theo <theom+news@chiark.greenend.org.uk> wrote:
> Jeff Layman <Jeff@invalid.invalid> wrote:
>> On 04/08/2023 22:19, Tim+ wrote:
>>>
>>> In a classic example of “Sod’s law” when the repair man came around to look
>>> at our 43 year Toshiba it started working perfectly. Made all the normal
>>> humming noises that had been absent before and made stuff hot.
>>
>> There's nothing like an intermittent fault to drive you round the bend.
>>
>> Well, if it has been working correctly, then you are now guaranteed to
>> have the HV capacitor(s) fully charged! If you do go fiddling around
>> inside, perhaps to change the magnetron, you'll have to be really
>> careful to make sure any caps are discharged completely.
>
> This. 2kV DC is no joke... especially due to 0.5*CV^2.
>
> These caps are about 1uF, so about 2 joules of stored energy. At 2kV that
> could be a very nasty zap.
>
>>> Can magnetron filaments behave like old light bulbs and start working again
>>> if shoogled a bit?
>>
>> I would very much doubt it.
>
> There is a heater element, which I suppose could do the light bulb thing,
> but seems unlikely. It could be insulation breaking down, either in the
> magnetron or capacitor.
>
>> One fairly simple thing to try if the fault's intermittent is to look
>> for a dry joint. If the circuitry is reasonably straightforward, a few
>> minutes going over any soldered joints with fresh solder can't harm.
>
> Could be that too, although I wonder how it's managed to have a dry joint
> after 43 years. Could be cracking of joints from thermal expansion I
> suppose.
>
> Theo
>

Well I’m a bit baffled as it’s working just fine now. It’s possible that
something temporarily overheated but it was only being used for a bit of
defrosting on a 50% duty cycle when it died so that seems unlikely.

Incidentally the suppliers of the compatible magnetron have confirmed that
it *is* compatible so I’ll give that a go if and when it dies again.

Tim
--
Please don't feed the trolls

On 05/08/2023 12:38, The Natural Philosopher wrote:
> On 05/08/2023 11:32, Jeff Layman wrote:
>> Of course, Brian, *proper* solder! I've still got a few metres of the
>> stuff for when it's required.
>>
> Its not illegal to sell it, just to use it in manufacturing
>
Not true. Military and Civil planes still use leaded solder.
Lead-free solder is not allowed according to my near neighbour
who used to be a licensed aircraft engineer for Virgin.

> Tons for sale everywhere.
>
> The point about lead free is its far harder to get it just right so it
> makes a decent joint. Amateurs are allowed to use tin/lead. As are some
> critical industries.
>
>

On 05/08/2023 18:35, Andrew wrote:
> On 05/08/2023 12:38, The Natural Philosopher wrote:
>> On 05/08/2023 11:32, Jeff Layman wrote:
>>> Of course, Brian, *proper* solder! I've still got a few metres of the
>>> stuff for when it's required.
>>>
>> Its not illegal to sell it, just to use it in manufacturing
>>
> Not true. Military and Civil planes still use leaded solder.
> Lead-free solder is not allowed according to my near neighbour
> who used to be a licensed aircraft engineer for Virgin.
>
Oh dear. You missed out the part of my post that said 'except for some
industries'

>> Tons for sale everywhere.
>>
>> The point about lead free is its far harder to get it just right so it
>> makes a decent joint. Amateurs are allowed to use tin/lead. As are
>> some critical industries.
>>
>>
>

--
I would rather have questions that cannot be answered...
....than to have answers that cannot be questioned

Richard Feynman

On Saturday, 5 August 2023 at 14:40:29 UTC+1, Tim+ wrote:
> Theo <theom...@chiark.greenend.org.uk> wrote:
> > Jeff Layman <Je...@invalid.invalid> wrote:
> >> On 04/08/2023 22:19, Tim+ wrote:
> >>>
> >>> In a classic example of “Sod’s law” when the repair man came around to look
> >>> at our 43 year Toshiba it started working perfectly. Made all the normal
> >>> humming noises that had been absent before and made stuff hot.
> >>
> >> There's nothing like an intermittent fault to drive you round the bend..
> >>
> >> Well, if it has been working correctly, then you are now guaranteed to
> >> have the HV capacitor(s) fully charged! If you do go fiddling around
> >> inside, perhaps to change the magnetron, you'll have to be really
> >> careful to make sure any caps are discharged completely.
> >
> > This. 2kV DC is no joke... especially due to 0.5*CV^2.
> >
> > These caps are about 1uF, so about 2 joules of stored energy. At 2kV that
> > could be a very nasty zap.
> >
> >>> Can magnetron filaments behave like old light bulbs and start working again
> >>> if shoogled a bit?
> >>
> >> I would very much doubt it.
> >
> > There is a heater element, which I suppose could do the light bulb thing,
> > but seems unlikely. It could be insulation breaking down, either in the
> > magnetron or capacitor.
> >
> >> One fairly simple thing to try if the fault's intermittent is to look
> >> for a dry joint. If the circuitry is reasonably straightforward, a few
> >> minutes going over any soldered joints with fresh solder can't harm.
> >
> > Could be that too, although I wonder how it's managed to have a dry joint
> > after 43 years. Could be cracking of joints from thermal expansion I
> > suppose.
> >
> > Theo
> >
> Well I’m a bit baffled as it’s working just fine now. It’s possible that
> something temporarily overheated but it was only being used for a bit of
> defrosting on a 50% duty cycle when it died so that seems unlikely.
>
> Incidentally the suppliers of the compatible magnetron have confirmed that
> it *is* compatible so I’ll give that a go if and when it dies again.
> Tim

I've seen no reason for it to b the magnetron, and would not replace bits at random.
You might begin by hanging meters off the transformer to see if it still gets power when it goes faulty, and divide the fault area from there. It's a slow process when it doesn't fault often, and you must deal safely with the potential serious electrical hazards with doing this unsafely.