In article ,
"ARW" writes:
I do not have a model number and it is a combi microwave.

All appears well but the microwave oven bit does not work (it goes through
the motions but does not actually heat anything up). I took the cover off
and the 5kV .8A fuse had blown.

A new fuse is £2 but what should I be looking at before just replacing the
fuse. Fuses seldom blow without reason.

A shorted HV rectifier or shorted HV capacitor would blow it.

Also, if the magnetron has somehow suffered a catastrophic internal
failure, it might end up with the anode and cathode shorted, but that
seems unlikely.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Andrew Gabriel wrote:
In article ,
"ARW" writes:
I do not have a model number and it is a combi microwave.

All appears well but the microwave oven bit does not work (it goes
through the motions but does not actually heat anything up). I took
the cover off and the 5kV .8A fuse had blown.

A new fuse is £2 but what should I be looking at before just
replacing the fuse. Fuses seldom blow without reason.

A shorted HV rectifier or shorted HV capacitor would blow it.

Also, if the magnetron has somehow suffered a catastrophic internal
failure, it might end up with the anode and cathode shorted, but that
seems unlikely.

Well I am sure I can test a rectifier, but how to test the cap?

I am happy to throw a few quid into getting it working but I do not want to
bugger around for days on end with the thing.

It's at my parents house and my Dad can get a couple of these ordered before
I go back there

http://www.ebay.co.uk/itm/Microwave-...-/280621034767



--
Adam

ARW expressed precisely :
Well I am sure I can test a rectifier, but how to test the cap?

I am happy to throw a few quid into getting it working but I do not want to
bugger around for days on end with the thing.

It's at my parents house and my Dad can get a couple of these ordered before
I go back there

http://www.ebay.co.uk/itm/Microwave-...-/280621034767

You cannot really test them properly, without the test voltage needed
for the test - just put another fuse in.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

On Sunday, August 25, 2013 4:22:11 PM UTC+1, wrote:
Andrew Gabriel wrote:
In article ,
"ARW" adamwadsworth writes:

I do not have a model number and it is a combi microwave.

All appears well but the microwave oven bit does not work (it goes
through the motions but does not actually heat anything up). I took
the cover off and the 5kV .8A fuse had blown.

Well I am sure I can test a rectifier, but how to test the cap?
I am happy to throw a few quid into getting it working but I do not want to
bugger around for days on end with the thing.
It's at my parents house and my Dad can get a couple of these ordered before
I go back there
http://www.ebay.co.uk/itm/Microwave-...-/280621034767

Simple, short the dead fuse & plug in. Nuke HV fuses just protect against fire risk from prolonged overrunning of the transformer. Testing it for a minute won't get it anywhere near hot enough. And millions of nukes have no such fuse too. If its ok with no fuse, fit one and its done.


NT

writes:

On Sunday, August 25, 2013 4:22:11 PM UTC+1, wro=
te:
Andrew Gabriel wrote:
In article ,
"ARW" adamwadsworth writes:

I do not have a model number and it is a combi microwave.

All appears well but the microwave oven bit does not work (it goes
through the motions but does not actually heat anything up). I took
the cover off and the 5kV .8A fuse had blown.

Well I am sure I can test a rectifier, but how to test the cap?

I was sure I could test a rectifier, then found out very belatedly that
the rectifier is internally a string of diodes in series. The result is
that it won't conduct in either direction if connected to a typical low
voltage ohmmeter. Which fooled me - you need maybe 15 or 20 volts to
make it conduct in the forward direction.

I am happy to throw a few quid into getting it working but I do not want =
to=20
bugger around for days on end with the thing.
It's at my parents house and my Dad can get a couple of these ordered bef=
ore=20
I go back there
http://www.ebay.co.uk/itm/Microwave-...ube-800mA-0-8=
A-5kV-/280621034767

Simple, short the dead fuse & plug in. Nuke HV fuses just protect against f=
ire risk from prolonged overrunning of the transformer. Testing it for a mi=
nute won't get it anywhere near hot enough. And millions of nukes have no s=
uch fuse too. If its ok with no fuse, fit one and its done.
--
Windmill, Use t m i l l
J.R.R. Tolkien:- @ S c o t s h o m e . c o m
All that is gold does not glister / Not all who wander are lost