Microwave diode bad?

A

Andrew Rossmann

Guest
I have an older, 1998 GE Microwave oven. By the LG parts inside,
probably just a rebadged LG. Lately, it's tended to 'thunk' when the
magnetron turns on. A few times, it started rapidly cycling. Once, I
didn't stop it in time and it blew it's 20A fuse. Another time, just
starting normally, it tripped a circuit breaker.

I opened it up and checked. So far, the only obvious thing I can see is
that the large diode between the transformer and ground may be open. I
get infinite resistance in both directions. I assume there is nothing
special about testing these types of diodes?

It's an HVR-1X diode. This appears, based on some Googling, to be very
common, and the HVR-1X3 seems to be a common replacement.

Do the symptoms I describe seem to go with the way the microwave is
acting? I'm not certain just what the true function of the diode is in
this case (I know how a diode itself works). There is also what looks
like a starter cap. It's rated at 1uF, and my meter says 1.15uF or so.

Do you think it's worth trying to replace it? I did buy a replacement
microwave, but regret it. It's basically the same, but has some issues I
don't like (display too far back from front, so you have to squat down
to see it while typing on the panel. Fan goes REAL fast when magnetron
off, then seems to nearly die when it's on.)

--
If there is a no_junk in my address, please REMOVE it before replying!
All junk mail senders will be prosecuted to the fullest extent of the
law!!
http://home.comcast.net/~andyross
 
On Sun, 28 Aug 2011 08:38:50 -0500, Andrew Rossmann
<andysnewsreply@no_junk.comcast.net> wrote:


I opened it up and checked. So far, the only obvious thing I can see is
that the large diode between the transformer and ground may be open. I
get infinite resistance in both directions. I assume there is nothing
special about testing these types of diodes?

It's an HVR-1X diode. This appears, based on some Googling, to be very
common, and the HVR-1X3 seems to be a common replacement.
Click to expand...
That diode is spec'ed at having a large forward voltage drop (10-14
volts). I regular ohm meter will not provide a voltage that high and
will show open.
 
A microwave diode is used as a mixer at microwave frequencies. You have
a microwave oven diode.


Andrew Rossmann wrote:
I have an older, 1998 GE Microwave oven. By the LG parts inside,
probably just a rebadged LG. Lately, it's tended to 'thunk' when the
magnetron turns on. A few times, it started rapidly cycling. Once, I
didn't stop it in time and it blew it's 20A fuse. Another time, just
starting normally, it tripped a circuit breaker.
Click to expand...

Check the waveguide to make sure it doesn't have food or grease in
it, and that the cover is in good shape.


I opened it up and checked. So far, the only obvious thing I can see is
that the large diode between the transformer and ground may be open. I
get infinite resistance in both directions. I assume there is nothing
special about testing these types of diodes?
Click to expand...

There are not regular diodes. There are a stack of diodes, and have
a higher forward voltage drop.


It's an HVR-1X diode. This appears, based on some Googling, to be very
common, and the HVR-1X3 seems to be a common replacement.

Do the symptoms I describe seem to go with the way the microwave is
acting? I'm not certain just what the true function of the diode is in
this case (I know how a diode itself works). There is also what looks
like a starter cap. It's rated at 1uF, and my meter says 1.15uF or so.
Click to expand...

That is a common oil filled HV cap. They usually fail shorted. Look
at the tolerance ratings on it. It's likely +/- 20%, which means the
reading is OK. Also, be careful inside a microwave. It can kill you in
a heartbeat. That cap should have a bleader resistor across it. If it
fails, the cap will retain a charge that will kill you.


Do you think it's worth trying to replace it? I did buy a replacement
microwave, but regret it. It's basically the same, but has some issues I
don't like (display too far back from front, so you have to squat down
to see it while typing on the panel. Fan goes REAL fast when magnetron
off, then seems to nearly die when it's on.)
Click to expand...

--
You can't have a sense of humor, if you have no sense.
 
In article <m4lk5711ubgcg2ecl252uged34clg47c3l@4ax.com>,
greenpjs@neo.rr.com says...
It's an HVR-1X diode. This appears, based on some Googling, to be
very
common, and the HVR-1X3 seems to be a common replacement.

That diode is spec'ed at having a large forward voltage drop (10-14
volts). I regular ohm meter will not provide a voltage that high and
will show open.
Click to expand...
Is there a simple setup I can create to test it?

--
If there is a no_junk in my address, please REMOVE it before replying!
All junk mail senders will be prosecuted to the fullest extent of the
law!!
http://home.comcast.net/~andyross
 
In article <MPG.28c41def789169f69897aa@news.eternal-september.org>,
andysnewsreply@no_junk.comcast.net says...
In article <m4lk5711ubgcg2ecl252uged34clg47c3l@4ax.com>,
greenpjs@neo.rr.com says...
It's an HVR-1X diode. This appears, based on some Googling, to be
very
common, and the HVR-1X3 seems to be a common replacement.

That diode is spec'ed at having a large forward voltage drop (10-14
volts). I regular ohm meter will not provide a voltage that high and
will show open.

Is there a simple setup I can create to test it?
Click to expand...
I guess I'll answer my own question! I used a 12V UPS battery I had
(12.89V measured) and checked if I could measure voltage through it. The
diode does work and measured about 9.5V.

Any other ideas on what could cause the power surge when the magnetron
is activated? The waveguide is clean. I removed the mica cover over it,
and there was nothing inside.

--
If there is a no_junk in my address, please REMOVE it before replying!
All junk mail senders will be prosecuted to the fullest extent of the
law!!
http://home.comcast.net/~andyross
 
On Sun, 28 Aug 2011 10:55:50 -0400, Michael A. Terrell wrote:
There are not regular diodes. There are a stack of diodes, and have
a higher forward voltage drop.
Click to expand...
Since there obviously lacking, their ought to be continuing education
classes where illiterates can improve they're language skills.
 
Andrew Rossmann wrote:

I have an older, 1998 GE Microwave oven. By the LG parts inside,
probably just a rebadged LG. Lately, it's tended to 'thunk' when the
magnetron turns on. A few times, it started rapidly cycling. Once, I
didn't stop it in time and it blew it's 20A fuse. Another time, just
starting normally, it tripped a circuit breaker.

I opened it up and checked. So far, the only obvious thing I can see is
that the large diode between the transformer and ground may be open. I
get infinite resistance in both directions. I assume there is nothing
special about testing these types of diodes?

It's an HVR-1X diode. This appears, based on some Googling, to be very
common, and the HVR-1X3 seems to be a common replacement.

Do the symptoms I describe seem to go with the way the microwave is
acting? I'm not certain just what the true function of the diode is in
this case (I know how a diode itself works). There is also what looks
like a starter cap. It's rated at 1uF, and my meter says 1.15uF or so.

Do you think it's worth trying to replace it? I did buy a replacement
microwave, but regret it. It's basically the same, but has some issues I
don't like (display too far back from front, so you have to squat down
to see it while typing on the panel. Fan goes REAL fast when magnetron
off, then seems to nearly die when it's on.)

That diode you speak of can not be tested in a conventional DIODE test
Click to expand...
in a DMM. It has several single diodes in series to up the over all
operating voltage, each one ~ 0.6 volt drop. Most basic diode modes in
DMM will only cover up to 2/3 in series. Long story short, you need
more voltage to be applied to the diode for a test. Some of us have
HV variable supplies, some crude, some elegant, like mine :)

A Varistate, HV transformer and HV probe works well to test these.

Jugging from your description, my guess would be a bad magnetron, one
that has an intermitting short.


Jamie
 
Andrew Rossmann wrote:

In article <MPG.28c41def789169f69897aa@news.eternal-september.org>,
andysnewsreply@no_junk.comcast.net says...

In article <m4lk5711ubgcg2ecl252uged34clg47c3l@4ax.com>,
greenpjs@neo.rr.com says...

It's an HVR-1X diode. This appears, based on some Googling, to be

very

common, and the HVR-1X3 seems to be a common replacement.

That diode is spec'ed at having a large forward voltage drop (10-14
volts). I regular ohm meter will not provide a voltage that high and
will show open.

Is there a simple setup I can create to test it?


I guess I'll answer my own question! I used a 12V UPS battery I had
(12.89V measured) and checked if I could measure voltage through it. The
diode does work and measured about 9.5V.

Any other ideas on what could cause the power surge when the magnetron
is activated? The waveguide is clean. I removed the mica cover over it,
and there was nothing inside.

Doing a forward test on a HV diode does not mean it's good, you still
Click to expand...
could have a break down problem with HV entered.

Jamie
 
Spamm Trappe wrote:

On Sun, 28 Aug 2011 10:55:50 -0400, Michael A. Terrell wrote:

There are not regular diodes. There are a stack of diodes, and have
a higher forward voltage drop.


Since there obviously lacking, their ought to be continuing education
classes where illiterates can improve they're language skills.
Click to expand...
Discussing such matters with MT is futile. Give it enough time, you'll
also be editing your list.

Jamie.
 
Spamm Trappe wrote:
On Sun, 28 Aug 2011 10:55:50 -0400, Michael A. Terrell wrote:
?
? There are not regular diodes. There are a stack of diodes, and have
? a higher forward voltage drop.

Since there obviously lacking, their ought to be continuing education
classes where illiterates can improve they're language skills.
Click to expand...

Since you want to point out typos, it's 'their language skills',
jackass.


--
You can't have a sense of humor, if you have no sense.
 
Spamm Trappe wrote:
Since there obviously lacking, their ought to be continuing education
classes where illiterates can improve they're language skills.

Michael A. Terrell wrote:
Since you want to point out typos, it's 'their language skills',
jackass.

Interesting that you dindn't mention the other 2
Click to expand...
purposeful misuses among there/their/they're
Satire is wasted on some people.
 
JeffM wrote:
Spamm Trappe wrote:
Since there obviously lacking, their ought to be continuing education
classes where illiterates can improve they're language skills.

Michael A. Terrell wrote:
Since you want to point out typos, it's 'their language skills',
jackass.

Interesting that you dindn't mention the other 2
purposeful misuses among there/their/they're
Satire is wasted on some people.
Click to expand...

One was enough. I made my mistakes from not enough sleep, for
months. Some days I'm in so much pain that I just don't give a damn.
Neither does my VA doctor, who thinks that the medication for diabetic
neuropathy is a real pain killer. He informed me that I was already on
'A very high dosage of pain killers'.


--
You can't have a sense of humor, if you have no sense.
 
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