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Anonymous Wrote:
Franc Zabkar <...@iinternode.on.net
Aside from the reliability issues which have been addressed in other
replies, it's possible that the HV diode died for reasons unrelated
to the inverter.
What does the oven do when you go to "cook". If nothing at all, then
there are almost certainly other bad parts, a fuse at the very least.
--
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Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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On Wed, 04 Mar 2009 16:10:38 +1100, Franc Zabkar <...@iinternode.on.net
On 03 Mar 2009 19:34:24 -0500, sa...@repairfaq.org (Samuel M.
Goldwasser) put finger to keyboard and composed:
I'm not sure where to look except for the magnetron.
Page 20 of the following service manual has a detailed circuit diagram
of the inverter:
http://www.eletrodomesticosforum.com/downloads/microondas/Panasonic_NN-G62BH.pd f
Page 42 of this manual has a block diagram of the controller chip:
http://rc5.ru/upload/panasonic_mw_NN-C2000_(MWO).pdf
I didn't test it in case something else broke, but my brother tells me
that everything appears to work except for the actual heating. That
is, the control panel works, the turntable turns, and the fan spins. A
shorted HV diode (there are two in a voltage doubler arrangement)
would mean that one of the 8200pF caps is now connected directly
across the secondary winding. I expect this would overload the
transformer and presumably the inverter would sense this fault
condition via the current transformer in the primary circuit. I'm told
that the oven shuts down after a time. Anyway I've ordered the diode
and I'll report back once I've tried it.
- Franc Zabkar
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On Thu, 05 Mar 2009 16:42:27 +1100, Franc Zabkar <...@iinternode.on.net
On Wed, 04 Mar 2009 16:10:38 +1100, Franc Zabkar
<...@iinternode.on.net
I replaced the HV diode and all appears well so far.
- Franc Zabkar
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Anonymous Wrote:
In article <...@4ax.com
I didn't know much about it. I bought one maybe 3 years ago. Small lightweight,
and the most powerfull one I have ever had. I use it everyday. The only problem, the light
does not come on when you open the door. My brother uses one in a resturant,
and they have failed after much use. That one the commercial job, costs a lot
more. Like I said, it small, powerfull, and cheap. My Sears GE microwave is
big, not nearly as powerfull, also has turbo oven, but I use the Panasonic
to heat fast. By other brother has a Samsung which has failed. Replaced
diode and found the transformer is bad. After two months still waiting for transformer.
greg
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On Tue, 3 Mar 2009 13:01:46 -0800 (PST), "hr(bob) hofm...@att.net" <...@att.net
Maybe the reason the light does not come on is because it is burned
out.
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Anonymous Wrote:
In article <...@o2g2000prl.googlegroups.com
The light comes on when its cooking. I usually carrry a flashlight so I can see the
condition of the food.
greg
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On Wed, 04 Mar 2009 08:20:56 -0600, jakdedert <...@bellsouth.net
<snipThat seems kind of obvious: door switch...probably gunked up with food
residue.
jak
> greg
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On Thu, 5 Mar 2009 01:04:07 +0000 (UTC), David Lesher <...@panix.com
jakdedert <...@bellsouth.net
My sister had one like that; light on during cook -- no light with the
door open. Dumb design.
I added a relay to solve the issue and was the big hero...
--
A host is a host from coast to coas...@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
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Anonymous Wrote:
In article <...@bignews6.bellsouth.net
It never worked. I don't see any reason to not believe thats the way its
designed. I need to hear from those who have these.
But, one day I'll open er up and change it.
I remember way back on an old Norelco microwave, the controller
failed, so I got out the old mechanical timer just like the one
on my first Heathkit microwave. I can't stress how this simple and easy
to use feature is missing on todays ovens. My father loved it.
I think on better models they used aother timer to cycle
the defrost. Those older models had at least 3 fail safe
microswitches on them, but the switch took the full current.
I'm sure in a fail safe mode, at least one microswitch in
ALL microwaves take the full current.
greg
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On Thu, 5 Mar 2009 07:32:39 -0800 (PST), "William R. Walsh" <...@hotmail.com
Hi!
I'm not sure I follow what you are saying. Are you saying that the
microwave, when its controller went bad, failed in an "on" position?
If I understand you correctly, I think it would be a far better idea
to have the oven fail in an "off" position.
Older microwaves sometimes had multiple timers. My grandfather has a
Litton microwave oven with two timers. One is the main timer, which is
an analog "knob" on the front. The other "timer" is engaged and used
in conjunction with the main timer when DEFROST mode is turned on. It
consists of a slow turning motor that drives an irregular cam. When
the cam rises up, it turns on a microswitch that enables the high
voltage and magnetron.
Today, the controller board in a "typical" oven has two relays...one
that runs the fan, turntable and light and another that can be turned
on and off to cycle the magnetron.
I'm not sure how long that technique was used, as I have a slightly
newer Litton microwave oven that is largely the same internally but
has a "rolling digits" timer and a solid-state control board for the
defrost and low power modes.
Newer microwaves also have multiple microswitches. (At least I have
yet to see one that does not, and that's on ovens manufactured as
recently as a year ago.) However, in normal operation, the microswitch
that interrupts the oven's operation when the door opens is actually a
low voltage signal to the controller board.
William
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On Tue, 3 Mar 2009 13:10:50 -0800, "Joel Koltner" <...@yahoo.com
"Franc Zabkar" <...@4ax.com...
Since they're a relatively new technology (at least at the consumer level), my
suspicion would be that, yeah, they are a bit less reliable.
There's also a bit of savings in lower freight costs from the lower weight.
And smaller people (women in particular) tend to put some emphasis on the
weight of their kitchen appliances, even if (as you point out) it's often
completely irrelevant once you get the thing up on the counter at home.
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On 3 Mar 2009 23:11:29 GMT, Jim Yanik <...@abuse.gov
"Joel Koltner" <...@en-nntp-01.dc1.easynews.com:
the savings is in not having to build an expensive,big transformer.
all that copper is expensive,too.
transformers,being far less complicated,are more reliable.
Inverters have a lot more components,particularly electrolytic caps,that
increase the odds of failure.
Many electrolytics are only rated for 3000 hrs or so of operation.
and it seems that surface-mount electrolytic caps are even less long-
lasting.
--
Jim Yanik
jyanik
at
kua.net
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On Thu, 5 Mar 2009 08:02:58 -0800 (PST), Tim Shoppa <...@trailing-edge.com
On Mar 3, 6:11 pm, Jim Yanik <...@abuse.gov
Microwave oven transformers are really quite undersized by
conventional engineering standards for the amount of power going
through them. Years of experience with the intermittent application
and detailed electrical+mechanical+thermal engineering for some
overtemp shutdowns is why they don't burn out despite being
undersized.
I suspect that with some experience under the belt that the inverters
can be made as reliable.
A lot of early consumer switching supplies weren't that good in their
first iterations either - electrolytics was at least one cause of the
problems.
Tim.
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On Tue, 3 Mar 2009 15:57:41 -0800 (PST), Mike WB2MEP <...@lmco.com
On Mar 3, 2:28 pm, Franc Zabkar <...@iinternode.on.net
Franc,
I don't think they're as reliable as conventional transformer/diode/
cap
power supplies. "Inverter" is just a switching power supply that
steps
up the voltage, and consumer-grade SMPS in a variety of products have
a
rather high failure rate.
There were several threads on SER a few years ago when Panasonic
first came out with the Inverter oves, about failures of the Inverter
circuit. At that time, Panasonic wouldn't sell replacement parts for
the Inverter power supply, or even provide a part number for the
switching trasistors that were failing. You had to replace the whole
power supply, which cost almost as much as a new oven.
The service manual for the NN-C2000 you linked to does have a parts
list for the Inverter board, so maybe they are considered repairable
now.
3 or 4 years ago, we needed a new microwave for the break room at
work.
Somebody donated an old (1984) Panasonic with a transformer power
supply,
and shortly thereafter a fancy new stainless-steel Panasonic Inverter
microwave was purchased. The two were used side-by-side for just over
a
year, then one day I came in and saw the Inverter oven set outside for
trash pickup.
So, I would definitely avoid the Inverter microwaves. Other
manufacturers
may be using switching power supplies, just not using the "Inverter"
name.
Last time I checked, most of the microwaves were still using
transformer
power supplies, but once the cost of a switching supply becomes less
than
a conventional supply, I would expect most of them to change over to
SMPS.
When you go into the store, just lift up the right side of each
microwave
on display, and buy the heaviest one.
Mike
WB2MEP
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On Thu, 05 Mar 2009 06:06:25 +1100, Franc Zabkar <...@iinternode.on.net
On Tue, 3 Mar 2009 15:57:41 -0800 (PST), Mike WB2MEP
<...@lmco.com
The transistors are now offered as "A691E4V10GP Transistor Kit Series
2".
Here are the datasheets for the GT30J322 (75W) and GT60M303 (170W)
IGBTs:
http://www.toshiba.com/taec/components2/Datasheet_Sync//361/4133.pdf
http://www.toshiba.com/taec/components2/Datasheet_Sync//361/4169.pdf
The oven has a rated output of 1100W. If the SMPS has an efficiency of
90%, then I expect that the transistors would be dissipating around
100W between them, although the mass of the heatsink appears
relatively small for such a high heat load.
- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
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On Sun, 08 Mar 2009 08:21:20 -0500, Rick <...@rcn.com
Heh - there's a Buyer's Guide tip you will never see in Consumer
Reports. <g
My favorite microwave oven is the Sharp "Carousel II" I pulled out of
the trash in 1994. Replaced an open fuse for about 50 cents and it's
been working fine ever since. I used that Sharp to replace a newer,
smaller model with less capacity and never regretted that decision.
It's a shame how many of the older models I've seen tossed that only
needed a fuse replacement.
Rick
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On Mon, 09 Mar 2009 09:09:03 +0800, rebel <...@privacy.net
Our National (aka Panasonic) Genius II from 1979 was running perfectly until a
power surge nuked it last year. Only ever needed a belt replaced. Weighed a
manly amount, about four times the weight of a contemporary unit.
I often utter that common remark "they don't make them like they used to".
Someone once said that's a sign I'm an old-timer. I replied that its a sign
that I remember how well they used to make things.
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On 8 Mar 2009 13:34:18 GMT, Jim Yanik <...@abuse.gov
sa...@repairfaq.org (Samuel M. Goldwasser) wrote in
news...@repairfaq.org:
My Carousel from early 1980s blew the HV capacitor after about 20
yrs,replaced it and the HV diode for $25 several years ago,it's still
running.
The MWs of today don't have as tall a cavity as my Sharp's.
--
Jim Yanik
jyanik
at
kua.net
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On Sun, 8 Mar 2009 09:06:07 -0700, "William Sommerwerck" <...@comcast.net
But I suspect it's not as wide.
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On 8 Mar 2009 17:03:52 GMT, Jim Yanik <...@abuse.gov
"William Sommerwerck" <...@reader.motzarella.org:
15.5" wide,10.25" high,and 16.5" deep,just measured it.
most MWs today are sandwich warmers....
I like to put a 2qt.pitcher in the MW and heat water in it for tea.
--
Jim Yanik
jyanik
at
kua.net
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On Sun, 08 Mar 2009 16:04:25 -0400, "Michael A. Terrell" <...@earthlink.net
I have a new Westinghouse 700 watt microwave, still in the box which
is 13*14*20 inches. The microwave itself would probably fit inside your
unit.
My dad bought it a few years ago for their motor home, and never
opened the box. It was in the huge pile of stuff they left here when
they sold their house in Florida and moved north. I haven't opened it,
because most of what I use a microwave for warns you not to use less
than a 1 KW unit.
--
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Goggle Groups, and Web TV users must request to be white listed, or I
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On Sun, 8 Mar 2009 13:43:04 -0700, "William Sommerwerck" <...@comcast.net
The only thing "wrong" with a 700W unit is that it won't heat things as
quickly. Which -- except for bacon and a few other things -- is all that
microwaves are good for -- heating and re-heating.
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On Mon, 09 Mar 2009 12:39:11 -0400, "Michael A. Terrell" <...@earthlink.net
Some items are marked, Do not use a microwave rated under 1 KW, to
prevent possible food posioning from under cooked meat. I have three
that are 1 KW or more, so why open the box? One is in the kitchen,
another is in the small cottage behind the house, and the third is a
spare. There are times I feel so bad I have to use a frozen dinner, and
i don't want to take chances. Other times I cook with one of my 5.5
quart crock pots.
--
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Goggle Groups, and Web TV users must request to be white listed, or I
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If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm
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On Mon, 9 Mar 2009 18:29:47 -0700, "William Sommerwerck" <...@comcast.net
I kinda, maybe, see the logic in that.
One should not be cooking meat in a microwave. (Other than bacon, I'm not
sure what sorts of mean /can/ be successfully cooked.
If you're heating up already-cooked items -- such as chicken nuggets -- the
only way you /might/ have a problem would be if you stuffed the oven with
several dozen, and the food stayed at an incubatory temperature long enough
for the bacteria to grow.
Even this is highly unlikely, as we're talking about pre-cooked food.
No obvious reason, other than that you raised the issue. (Nothing personal.)
You'll probably be upset to learn that, when I eat frozen dinners at work, I
let them completely defrost before shoving them in the microwave. It's
quicker, saves a bit of energy, and I'm not dead -- yet.
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On Tue, 10 Mar 2009 03:09:16 -0400, "Michael A. Terrell" <...@earthlink.net
A high power microwave will cook most meat, but doesn't brown it.
One thing that helps is to cook it about 2/3 of the required time, pour
off the fat and juices, and finish cooking. I cook hamburgers and small
steaks in mine. i add the spices and some dried onions before cooking,
so the steam and juices re hydrate the chopped onions and add their
flavor to the meat.
I have made meat loaf as well, but they are hard to drain the fat and
a little messy. I also precook some meat for homemade soup, to reduce
the cooking time in the crock pot. Another trick is to add a little
instant mashed potatoes to the soup to thicken it.
My favorite frozen dinner is a pot roast, with a side of green beans.
Nothing is completely pre-cooked, and it has the warning about using sub
KW microwaves. Sometimes they are in the freezer for a month, and
others, they are daily meals.
Having to survive on a minuscule VA Disability pension has forced me
to get creative because a full tank of propane for the gas stove just
isn't in the budget.
I generally only use frozen dinners when I'm too sick to cook, and I
never know when that will be. I used to put what I planned to microwave
into the fridge the night before, but quit when I had to throw out food
that spoiled before I could cook it. Its hard to be ready to fix a
planed meal on time, and some days I can barely even face food, let
alone what was planned.
--
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Goggle Groups, and Web TV users must request to be white listed, or I
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If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm
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On Tue, 10 Mar 2009 04:35:09 -0700, "William Sommerwerck" <...@comcast.net
I'm sorry to hear you're feeling so bad. One of my best friends died several
years ago from cancer-induced starvation. He almost completely lost his
appetite, even to the point of finding many foods bad-tasting.
If there's anything I can do to help, let me know and I'll try.
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On 10 Mar 2009 13:03:20 GMT, Jim Yanik <...@abuse.gov
"William Sommerwerck" <...@news.motzarella.org:
smoke pot. 8-)
(is that an offer to supply some MJ??? <grin
--
Jim Yanik
jyanik
at
kua.net
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Anonymous Wrote:
In article <...@earthlink.com
They used to sell microwaves with browners. Of course, they still make combp
microwave/ Turbo ovens. I could not live without my little turbo oven.
Everybody is amazed who use it. You can cook most anything in
the microwave safely buy covering it and let it steam all the way through.
I would recommend my turbo oven but its not made anymore.
There is no substitute, and I have fixed it once. I'll try to keep fixing it
as long as I can. The burner connections go bad. i have two other turbo
ovens and they don't compare.
greg
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On 10 Mar 2009 16:41:35 GMT, Jim Yanik <...@abuse.gov
zekf...@zekfrivolous.com (GregS) wrote in
news...@usenet01.srv.cis.pitt.edu:
cooking a STEAK in a microwave?
Sacrilege. you might as well boil it.
same for the burger.
--
Jim Yanik
jyanik
at
kua.net
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Anonymous Wrote:
In article <...@74.209.136.87
Cooking in the turbo oven is the only way, except for charbroil.
I never said a microwave was the best way, allthough a combo
turbo/microwave can be used in turbo mode. It still does not brown properly
cause a turbo/microwave has no exposed radiating elements.
I tried getting the company to start making this oven again. Communicating
with companies like Salton who marketed the Toatmaster consumer grade product,
is next to impossible.
greg
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