It's quite old, but a match to the double Neff Oven.

The time display goes blank after use. Otherwise it works normally for
setting the operating time. Press stop, and it appears at 12.00. Can then
be set and works normally, until the unit is used again.

Is there an internal battery that might have failed? It is never powered
down.

--
*Why is "abbreviated" such a long word?

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:

The time display goes blank after use.

I think the time display on my neff m/w blanks between certain hours,
yours doesn't think it's 9pm when it's really 9am does it?

In article ,
Andy Burns wrote:
Dave Plowman (News) wrote:

The time display goes blank after use.

I think the time display on my neff m/w blanks between certain hours,
yours doesn't think it's 9pm when it's really 9am does it?

Mine doesn't. And since with this fault you have to reset the time after
using it, unlikely. ;-)

--
*Vegetarians taste great*

Dave Plowman London SW
To e-mail, change noise into sound.

On 05/11/2020 15:44, Dave Plowman (News) wrote:
It's quite old, but a match to the double Neff Oven.

The time display goes blank after use. Otherwise it works normally for
setting the operating time. Press stop, and it appears at 12.00. Can then
be set and works normally, until the unit is used again.

Is there an internal battery that might have failed? It is never powered
down.

I wouldn't have thought so. Cookers are amongst the most annoying white
goods that forget the time whenever there is a short powercut.

They then choose either:

to restart as if from midnight 1/1/1980
or
flash 00:00 and refuse to do anything until you set the system clock.

We have one in each camp and of the same brand so it is possible to
infer both that there has been a power cut and also how long ago.

--
Regards,
Martin Brown

Dave Plowman (News) wrote:
In article ,
Andy Burns wrote:
Dave Plowman (News) wrote:

The time display goes blank after use.

I think the time display on my neff m/w blanks between certain hours,
yours doesn't think it's 9pm when it's really 9am does it?

Mine doesn't. And since with this fault you have to reset the time after
using it, unlikely. ;-)


Sounds like the DC power supply for the controller board
is winking out for some reason. Like maybe when the
microwave oven door opens and the light comes on ?

You'd need to dig up a sample schematic for a microwave,
to see what "best practice/cheapest method" looks like
and from there, figure out the fault modes possible.

My previous microwave needed a pretty decent DC voltage,
since the display was vacuum fluorescent and the segment
drive for that is like 18-27VDC or so. Other technologies will
need different voltages. A LED based display could be
neatly done off 5VDC. The voltage doesn't particularly
matter, just find how they're making that voltage, and
trace what could be shorting it out and causing it
to current limit.

There's nothing adventurous about this one. A 5V design
based off a 7805 (1 amp) regulator. The unregulated
rail is used for relay drive, so that the relay current
doesn't overtax the 7805. 7805 has thermal cutout, if
it gets too hot, output is cut off. And naturally,
they'll put the 7805 in there, with no heatsink on it.
Because heatsinks cost money.

https://www.electronicsforu.com/wp-c...owave-oven.jpg

That schematic is "too pretty" to be real. Real schematics,
the controller board doesn't have the 7805 on it, and
the power components would be on another page of schematic,
poorly labeled and impossible to follow. That's how real
schematic drawing works :-)

The relays around the edge, could be feeding interfaces
on the microwave board, whatever that is. They'd likely
want some isolation between the two circuits, to reduce
the opportunities for HV leakage from the microwave
section, blowing up the controller.

You'd be looking for a center tapped transformer wire
set, three wires, feeding from some transformer to the
controller board. And right after that should be
some rectifiers to make pulsating DC. Which needs to be
filtered by a cap. Check the cap for brown leakage.
High voltage caps, the fabrication is pretty careful.
Filter caps for 5V, any Chinese junk will do.

Paul

Yes I had that issue with a 12v regulator in a cassette deck. shove a heat
sink on it and all was sweetness and light. Insufficient testing.
However in this case I'm intrigued why would a time be needed to be blanked
at any time of day? Is it made by weigh****chers, ie after 9pm you are not
allowed to cook? grin

Brian

--

This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Paul" wrote in message
...
Dave Plowman (News) wrote:
In article ,
Andy Burns wrote:
Dave Plowman (News) wrote:

The time display goes blank after use.

I think the time display on my neff m/w blanks between certain hours,
yours doesn't think it's 9pm when it's really 9am does it?

Mine doesn't. And since with this fault you have to reset the time after
using it, unlikely. ;-)


Sounds like the DC power supply for the controller board
is winking out for some reason. Like maybe when the
microwave oven door opens and the light comes on ?

You'd need to dig up a sample schematic for a microwave,
to see what "best practice/cheapest method" looks like
and from there, figure out the fault modes possible.

My previous microwave needed a pretty decent DC voltage,
since the display was vacuum fluorescent and the segment
drive for that is like 18-27VDC or so. Other technologies will
need different voltages. A LED based display could be
neatly done off 5VDC. The voltage doesn't particularly
matter, just find how they're making that voltage, and
trace what could be shorting it out and causing it
to current limit.

There's nothing adventurous about this one. A 5V design
based off a 7805 (1 amp) regulator. The unregulated
rail is used for relay drive, so that the relay current
doesn't overtax the 7805. 7805 has thermal cutout, if
it gets too hot, output is cut off. And naturally,
they'll put the 7805 in there, with no heatsink on it.
Because heatsinks cost money.

https://www.electronicsforu.com/wp-c...owave-oven.jpg

That schematic is "too pretty" to be real. Real schematics,
the controller board doesn't have the 7805 on it, and
the power components would be on another page of schematic,
poorly labeled and impossible to follow. That's how real
schematic drawing works :-)

The relays around the edge, could be feeding interfaces
on the microwave board, whatever that is. They'd likely
want some isolation between the two circuits, to reduce
the opportunities for HV leakage from the microwave
section, blowing up the controller.

You'd be looking for a center tapped transformer wire
set, three wires, feeding from some transformer to the
controller board. And right after that should be
some rectifiers to make pulsating DC. Which needs to be
filtered by a cap. Check the cap for brown leakage.
High voltage caps, the fabrication is pretty careful.
Filter caps for 5V, any Chinese junk will do.

Paul

I wonder could this be a leaky electrolytic which is supposed to cover a bit
of a pulse in the supply but no longer does?
Brian

--

This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Martin Brown" wrote in message
...
On 05/11/2020 15:44, Dave Plowman (News) wrote:
It's quite old, but a match to the double Neff Oven.

The time display goes blank after use. Otherwise it works normally for
setting the operating time. Press stop, and it appears at 12.00. Can
then
be set and works normally, until the unit is used again.

Is there an internal battery that might have failed? It is never powered
down.

I wouldn't have thought so. Cookers are amongst the most annoying white
goods that forget the time whenever there is a short powercut.

They then choose either:

to restart as if from midnight 1/1/1980
or
flash 00:00 and refuse to do anything until you set the system clock.

We have one in each camp and of the same brand so it is possible to infer
both that there has been a power cut and also how long ago.

--
Regards,
Martin Brown

On 05/11/2020 18:46, Paul wrote:
Dave Plowman (News) wrote:
In article ,
Â*Â* Andy Burns wrote:
Dave Plowman (News) wrote:

The time display goes blank after use.

I think the time display on my neff m/w blanks between certain hours,
yours doesn't think it's 9pm when it's really 9am does it?

Mine doesn't. And since with this fault you have to reset the time after
using it, unlikely. ;-)


Sounds like the DC power supply for the controller board
is winking out for some reason. Like maybe when the
microwave oven door opens and the light comes on ?

You'd need to dig up a sample schematic for a microwave,
to see what "best practice/cheapest method" looks like
and from there, figure out the fault modes possible.

My previous microwave needed a pretty decent DC voltage,
since the display was vacuum fluorescent and the segment
drive for that is like 18-27VDC or so. Other technologies will
need different voltages. A LED based display could be
neatly done off 5VDC. The voltage doesn't particularly
matter, just find how they're making that voltage, and
trace what could be shorting it out and causing it
to current limit.

There's nothing adventurous about this one. A 5V design
based off a 7805 (1 amp) regulator. The unregulated
rail is used for relay drive, so that the relay current
doesn't overtax the 7805. 7805 has thermal cutout, if
it gets too hot, output is cut off. And naturally,
they'll put the 7805 in there, with no heatsink on it.
Because heatsinks cost money.

https://www.electronicsforu.com/wp-c...owave-oven.jpg


That schematic is "too pretty" to be real. Real schematics,
the controller board doesn't have the 7805 on it, and
the power components would be on another page of schematic,
poorly labeled and impossible to follow. That's how real
schematic drawing works :-)

The relays around the edge, could be feeding interfaces
on the microwave board, whatever that is. They'd likely
want some isolation between the two circuits, to reduce
the opportunities for HV leakage from the microwave
section, blowing up the controller.

You'd be looking for a center tapped transformer wire
set, three wires, feeding from some transformer to the
controller board. And right after that should be
some rectifiers to make pulsating DC. Which needs to be
filtered by a cap. Check the cap for brown leakage.
High voltage caps, the fabrication is pretty careful.
Filter caps for 5V, any Chinese junk will do.

Â*Â* Paul


--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 05/11/2020 18:46, Paul wrote:

https://www.electronicsforu.com/wp-c...owave-oven.jpg


That schematic is "too pretty" to be real. Real schematics,
the controller board doesn't have the 7805 on it, and
the power components would be on another page of schematic,
poorly labeled and impossible to follow. That's how real
schematic drawing works :-)


Ab alternative from bigClive
https://www.youtube.com/watch?v=WvpIgxB_a7w
--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 05/11/2020 17:03, Martin Brown wrote:


I wouldn't have thought so. Cookers are amongst the most annoying white
goods that forget the time whenever there is a short powercut.

Getting them on the internet of things can't happen too soon for my liking.

I was rather pleased to find that my new latest toy (GoPro 9) sets the
date and time either when you enable GPS or connect it to a smart phone.

On 05/11/2020 21:26, newshound wrote:
On 05/11/2020 17:03, Martin Brown wrote:


I wouldn't have thought so. Cookers are amongst the most annoying
white goods that forget the time whenever there is a short powercut.

Getting them on the internet of things can't happen too soon for my liking.

Mine blew up destroyed the magnetron inside guarantee a few years back
and I was surprised to see inside that the mother board had a wifi
networking chipset on it. The service guy told me that in theory you
could scan the QR code on a product and it sets the timer accordingly.

However, AFAIK this functionality has still not been fully implemented
on any production models or enabled on existing ones. The hardware was
physically present in the build but the firmware support was/is not.

I was rather pleased to find that my new latest toy (GoPro 9) sets the
date and time either when you enable GPS or connect it to a smart phone.

GPS has become the time standard of choice these days.

--
Regards,
Martin Brown

newshound wrote:

Martin Brown wrote:

Cookers are amongst the most annoying
white goods that forget the time whenever there is a short powercut.

Getting them on the internet of things can't happen too soon for my liking.

Or just remove the clock functionality and leave them with timers; I
mean honestly who has ever gone to work and set the oven to have their
tea cooked ready for whatever time they expect to get home?

I suppose we should be grateful washing machines don't have clocks too.

In article ,
Andy Burns wrote:
newshound wrote:

Martin Brown wrote:

Cookers are amongst the most annoying
white goods that forget the time whenever there is a short powercut.

Getting them on the internet of things can't happen too soon for my liking.

Or just remove the clock functionality and leave them with timers; I
mean honestly who has ever gone to work and set the oven to have their
tea cooked ready for whatever time they expect to get home?

I suppose we should be grateful washing machines don't have clocks too.


Only time I've used the timer is for an enormous turkey Xmas day. Worked
just fine.

--
*Fax is stronger than fiction *

Dave Plowman London SW
To e-mail, change noise into sound.