We have a dead combi microwave.

Fisrt test - get the back off.
Fortunately I have a set of security bits so can take the special screws
out.

Second test - check fuse where the power comes in.
This is O.K. according to my multi-meter.

Third test?
Suggestions please.

Looking back I see that microwaves are supposed to be 'very fixable' but
there's an awful lot of wiring in there.

TIA

Dave R

--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

David WE Roberts wrote:

Looking back I see that microwaves are supposed to be 'very fixable' but
there's an awful lot of wiring in there.

Usually, if everything works bar actually zapping anything then it's the
magnetron.

Fixed one t'other month (expensive combi so better to repair than
replace with a Tesco £20 one) and, before ordering a spare, tested my
theory by using the 'broken' microwave to power the magnetron in situ in
another microwave that was kicking about.

And lo, the mutant hybrid two microwave monster made some water warm.

A new ebay special magnetron was purchased, fitted and is working well.

Scott

On 24/09/2012 13:41, David WE Roberts wrote:
We have a dead combi microwave.

Fisrt test - get the back off.
Fortunately I have a set of security bits so can take the special screws
out.

Second test - check fuse where the power comes in.
This is O.K. according to my multi-meter.

Third test?
Suggestions please.

Looking back I see that microwaves are supposed to be 'very fixable' but
there's an awful lot of wiring in there.

TIA

Dave R


Does *anything* work? If the grill works but the microwave doesn't, it
could well be a problem with the micro-switches on the door - which
provide a fairly complex interlock to prevent you from microwaving yourself.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On Monday, September 24, 2012 1:43:19 PM UTC+1, David WE Roberts wrote:
We have a dead combi microwave.



Fisrt test - get the back off.

Fortunately I have a set of security bits so can take the special screws

out.



Second test - check fuse where the power comes in.

This is O.K. according to my multi-meter.



Third test?

Suggestions please.



Looking back I see that microwaves are supposed to be 'very fixable' but

there's an awful lot of wiring in there.



TIA



Dave R

If that's all you know to do, I'd leave it alone. The HV cap plus various wiring connected to it can sometimes kill you and a whole queue of people in an instant.

If there's no sign of life at all, first thing I'd do after discharging the cap is check the fuse inside the microwave. If its o/c, odds are an interlock failure took it out. Replacing the fuse without fixing the problem is dangerous, as the machine then has a faulty interlock plus probably an o/c shorting resistor.


NT

and they can be extremely dangerous as well if you stick fingers in even if
its been off for a while.

Brian

--
From the Sofa of Brian Gaff Reply address is active
"David WE Roberts" wrote in message
...
We have a dead combi microwave.

Fisrt test - get the back off.
Fortunately I have a set of security bits so can take the special screws
out.

Second test - check fuse where the power comes in.
This is O.K. according to my multi-meter.

Third test?
Suggestions please.

Looking back I see that microwaves are supposed to be 'very fixable' but
there's an awful lot of wiring in there.

TIA

Dave R

--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

Not much to go wrong with a magnetron, though I have had some that were low
output. However I doubt that much care is taken to make sure they will last
too long when they are made, no doubt to a price.
Handy magnets to keep though.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"Scott M" wrote in message
...
David WE Roberts wrote:

Looking back I see that microwaves are supposed to be 'very fixable' but
there's an awful lot of wiring in there.

Usually, if everything works bar actually zapping anything then it's the
magnetron.

Fixed one t'other month (expensive combi so better to repair than replace
with a Tesco £20 one) and, before ordering a spare, tested my theory by
using the 'broken' microwave to power the magnetron in situ in another
microwave that was kicking about.

And lo, the mutant hybrid two microwave monster made some water warm.

A new ebay special magnetron was purchased, fitted and is working well.

Scott

Well seen no feedback hope you have not killed yourself..
Brian

--
From the Sofa of Brian Gaff Reply address is active
"David WE Roberts" wrote in message
...
We have a dead combi microwave.

Fisrt test - get the back off.
Fortunately I have a set of security bits so can take the special screws
out.

Second test - check fuse where the power comes in.
This is O.K. according to my multi-meter.

Third test?
Suggestions please.

Looking back I see that microwaves are supposed to be 'very fixable' but
there's an awful lot of wiring in there.

TIA

Dave R

--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

On Sep 24, 1:43*pm, "David WE Roberts" wrote:
We have a dead combi microwave.

It's filthy inside and new ones are cheap.

Scrap it, save the bits, make yourself a halloween ghost out of the
turntable motor.

On Sep 24, 4:11*pm, wrote:

The HV cap plus various wiring connected to it can sometimes kill you and a whole queue of people in an instant.

Only if you get them to all stand in a circle holding hands...


....so I guess that's the next Hackspace meeting taken care of then!

On Monday, September 24, 2012 6:42:23 PM UTC+1, Andy Dingley wrote:
On Sep 24, 1:43*pm, "David WE Roberts" wrote:

We have a dead combi microwave.



It's filthy inside and new ones are cheap.



Scrap it, save the bits, make yourself a halloween ghost out of the

turntable motor.

or use it as a megger


NT

On Mon, 24 Sep 2012 13:41:47 +0100, "David WE Roberts"
wrote:

We have a dead combi microwave.

Fisrt test - get the back off.
Fortunately I have a set of security bits so can take the special screws
out.

Second test - check fuse where the power comes in.
This is O.K. according to my multi-meter.

Third test?
Suggestions please.

Looking back I see that microwaves are supposed to be 'very fixable' but
there's an awful lot of wiring in there.

TIA

Dave R

It would help a great deal if you gave the make and model so we knew
what we are dealing with.
Does it have a permanent display of some kind? a clock perhaps,
If it has, and I assume this is also not working look for a small
transformer that supplies the control panel, this will probably have
its own fuse on the primary side, and a conventional bridge rectifier
and smoothing cap on the secondary side.

Typically there is a relay on the control board that energises the big
transformer.

Be careful.




--
Graham.
%Profound_observation%

"David WE Roberts" wrote in message
...
We have a dead combi microwave.

Fisrt test - get the back off.
Fortunately I have a set of security bits so can take the special screws
out.

Second test - check fuse where the power comes in.
This is O.K. according to my multi-meter.

Third test?
Suggestions please.

Looking back I see that microwaves are supposed to be 'very fixable' but
there's an awful lot of wiring in there.


More information.
[Microwave has been sitting in the shed for a couple of years after being
reported dead by No. 1 daughter.]

Combi microwave, grill, convection oven.

Cookworks brand (model unknown ATM).

After looking inside and checking the power fuse, put it back together and
tested.
[Getting the case back on was interesting - like early PCs before they
worked out that easy removal and replacement of the case was a good idea.]

Display lights up and controls work.

On 'microwave' the light comes on, the turntable turns, but a cup of water
stays cold.
[So probably not a door interlock problem.]

Grill works.

Convection oven works.

So it looks like the Magnetron (wasn't that one of the Transformers?) is not
working.

If I knew which internal bit it was I might be tempted to change it.

However when the new kitchen arrives it will include a built in microwave.
We have a replacement simple microwave.
We currently lack a grill and oven (old kitchen long gone to the scrap
heap).
So for the moment we will run two devices - on as a microwave and the other
as an oven/grill.

I would like to repair this one just for the learning experience but lack of
time will prevent me before it becomes redundant.

Some interesting large pieces of heavy metal inside, but I must resist!

Thanks for all the replies.

Cheers

Dave R
--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

On Tuesday, September 25, 2012 7:52:20 AM UTC+1, David WE Roberts wrote:
"David WE Roberts" nospam wrote in message

...

We have a dead combi microwave.



Fisrt test - get the back off.

Fortunately I have a set of security bits so can take the special screws

out.



Second test - check fuse where the power comes in.

This is O.K. according to my multi-meter.



Third test?

Suggestions please.



Looking back I see that microwaves are supposed to be 'very fixable' but

there's an awful lot of wiring in there.





More information.

[Microwave has been sitting in the shed for a couple of years after being

reported dead by No. 1 daughter.]



Combi microwave, grill, convection oven.



Cookworks brand (model unknown ATM).



After looking inside and checking the power fuse, put it back together and

tested.

[Getting the case back on was interesting - like early PCs before they

worked out that easy removal and replacement of the case was a good idea.]



Display lights up and controls work.



On 'microwave' the light comes on, the turntable turns, but a cup of water

stays cold.

[So probably not a door interlock problem.]



Grill works.



Convection oven works.



So it looks like the Magnetron (wasn't that one of the Transformers?) is not

working.



If I knew which internal bit it was I might be tempted to change it.



However when the new kitchen arrives it will include a built in microwave.

We have a replacement simple microwave.

We currently lack a grill and oven (old kitchen long gone to the scrap

heap).

So for the moment we will run two devices - on as a microwave and the other

as an oven/grill.



I would like to repair this one just for the learning experience but lack of

time will prevent me before it becomes redundant.



Some interesting large pieces of heavy metal inside, but I must resist!



Thanks for all the replies.



Cheers



Dave R


Good news: I'm putting together a wiki article on repairing microwaves.
Bad news: it could be any of a list of parts
Good news: without fault finding there are things that can be tried.


NT

Good news: I'm putting together a wiki article on repairing microwaves.
Bad news: it could be any of a list of parts
Good news: without fault finding there are things that can be tried.


NT

Care to post a draft of what you've written so far?

--
Graham.
%Profound_observation%

wrote:

If that's all you know to do, I'd leave it alone. The HV cap plus various wiring connected to it can
sometimes kill you and a whole queue of people in an instant.

Remembering that you usually say this, last time I was playing with one
I went at the cap with my meter.

Flat as a flat flat thing.

I can't remember if I already had the lid off or it was in the time
taken to remove the case.

--
Scott

Where are we going and why am I in this handbasket?

On Sep 25, 7:15*pm, Scott M wrote:
Flat as a flat flat thing.

That's because it has a bleed resistor.

Now take the resistor off, leave it a day and measure again.

(The last bit does depend on the dielectric. However if you have
_real_ HT supplies, it's an issue.)

On Tue, 25 Sep 2012 12:00:51 -0700 (PDT), Andy Dingley
wrote:

On Sep 25, 7:15*pm, Scott M wrote:
Flat as a flat flat thing.

That's because it has a bleed resistor.

Now take the resistor off, leave it a day and measure again.

(The last bit does depend on the dielectric. However if you have
_real_ HT supplies, it's an issue.)

The bleed resistor is an integral part of the oil-filled capacitor.
That's not to say that it couldn't go O/C, it's just that I have
personally never known it to happen.

--
Graham.
%Profound_observation%

Graham. wrote:

Flat as a flat flat thing.
That's because it has a bleed resistor.

Now take the resistor off, leave it a day and measure again.


The bleed resistor is an integral part of the oil-filled capacitor.
That's not to say that it couldn't go O/C, it's just that I have
personally never known it to happen.

ding The circuit diagram showed the bleed resistor and, from various
dire warnings, I assumed that it'd be a sufficiently large value to take
ages to flatten the thing. Was surprised that it was so quick.

Scott