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GE Microwave JVM1540DM3WW Everything but Heat

A

amdx

Jan 1, 1970
0
Ian Field skrev den 05/04/2013:


Another thing to consider is the resulting effect of the microwave.

Using these formulas:

1 Ws = 1J

4.184 J for the temperature of one gram of water to increase 1 degree
Celsius (°C).

Then take the time for 100g=1dl tap-water to boil from tap-temperature,
perhaps 10C, it is easy to calculate the resulting effect.

(And here you see the advantage of using metric, instead of units based
on the length of king X's thumb and the volume of his bladder or
whatever :) )

Doing that, I discovered my microwave, labeled 900w, actually delivered
250w.

I don't know if it still takes 900w from the mains, but I discarded it
and replaced it.

technically, you might have called it "working" :)

Leif
Is it necessarily true that all the microwaves leaving the magnetron
are being focused in your bowl of water?
Mikek
 
W

William Sommerwerck

Jan 1, 1970
0
Is it necessarily true that all the microwaves leaving the
magnetron are being focused in your bowl of water?

Those that miss the bowl bounce around until they're absorbed.
 
C

Cydrome Leader

Jan 1, 1970
0
Ian Field said:
Some ovens have a "pin-pivot" set of vanes hidden behind a low dielectric
ceramic panel, the microwaves bouncing off the vanes pushes them round; thus
causing a constantly varied angle of incidence for the waves to bounce
around the compartment.

I've not seen this in years, or goofy stuff like temperate probes either.

Who really cooks a turkey in the microwave?
 
C

Cydrome Leader

Jan 1, 1970
0
amdx said:
I have a working Frigidaire microwave that was manufactured in 1983.
The specs say 1.38 KW 120V 60HZ, a little odd, now it would be amps not
KW. Don't know about the output power, nothing on the unit, and the
owners manual says nothing about the power. The model number is MC800M,
I would think 800W is to low for the output power. But, I'm curious what
is the efficiency of a magnetron?
Mikek

Mine has a spec sheet indicating input power of 1.25kW and 14.5A and
output power of 70 to 700W in 10 steps, or 56% efficient as a whole. I'd
hope new ones are slightly better than this. This thing also has a listed
weight of 80 pounds which is without question, accurate. The manufacture
date is June, 1981. It's possible the 700W is optimistic, but at least
more honest than the numbers you see on vacuum cleaners, like 6
horsepower.
PS. The owners manual says " If you move or sell the microwave to
another person please report the change so we can update our records.
Hope I'm not in trouble, I've moved 5 times without reporting. :)

Mine mentions not to put the temperature probe into frozen food as
breakage can occur, and that you should not dry clothing or wet newspapers
with it.

When did they start to plastic bag newspapers?
 
W

William Sommerwerck

Jan 1, 1970
0
I've not seen this in years, or goofy stuff like temperate
probes either.

I prefer the intemperate ones... Much more fun.

Who really cooks a turkey in the microwave?

No one in their right mind.

Microwave ovens don't actually cook anything. They just heat it.
 
P

Phil Allison

Jan 1, 1970
0
"amdx"
I have a working Frigidaire microwave that was manufactured in 1983.
The specs say 1.38 KW 120V 60HZ, a little odd, now it would be amps not
KW. Don't know about the output power, nothing on the unit, and the owners
manual says nothing about the power. The model number is MC800M,
I would think 800W is to low for the output power. But, I'm curious what
is the efficiency of a magnetron?


** My Samsung MB245 is rated at 1000W and has a nameplate consumption of
1650W.

The AC current draw is 7 amps at 240V.


..... Phil
 
T

Trevor Wilson

Jan 1, 1970
0
Everything operates correctly, except no heat. I can hear a transformer hum, come and go while it acts like it is working, like it is trying to run, but nothing heats. I understand electrical systems and have read considerable about troubleshooting and repair. I just wanted to ask before undertaking this task. Based on the circumstances with the on and off hum, what do you think?

Thank you ...Ken

**Commonly, the fault is that the magnetron has failed. HOWEVER, as PA
mentioned, inexperienced people should NEVER attempt to repair a
microwave oven. Even after switching off, sufficient energy may be
stored in the main filter cap to kill a human. When powered up, the
danger is further magnified. 2,000 Volts at 0.5 Amp will easily kill.
 
C

Cydrome Leader

Jan 1, 1970
0
William Sommerwerck said:
I prefer the intemperate ones... Much more fun.



No one in their right mind.

Microwave ovens don't actually cook anything. They just heat it.

they are unsurpassed for stuff like frozen burritos or fresh broccoli.

And also accumulating that microwave oven smell, no matter what's heated
up in them.
 
T

Trevor Wilson

Jan 1, 1970
0
Utter rubbish! - the mains filter cap is insignificant, its the hefty
cap in the doubler circuit that could be dangerous.

**I said:

"...the MAIN filter cap..." Not MAINS filter cap (whatever that is). I
did not assume a SMPS, rather a linear supply. The cap in question can
store several kV.

The transformer secondary delivers 2kV at enough current to guarantee
lethality, it can strike an arc to your hand through a cracked
screwdriver handle and kill you!

**Of course.
The capacitor in the doubler is typically 0.9uF - 1uF and can remain
charged upto some proportion of 2kV.

**That is exactly what I stated.
 
C

Cydrome Leader

Jan 1, 1970
0
Ian Field said:
Utter rubbish! - the mains filter cap is insignificant, its the hefty cap in
the doubler circuit that could be dangerous.


The transformer secondary delivers 2kV at enough current to guarantee
lethality, it can strike an arc to your hand through a cracked screwdriver
handle and kill you!

The capacitor in the doubler is typically 0.9uF - 1uF and can remain charged
upto some proportion of 2kV.

plus you need a good pair of leather gloves just to open them these days.
The sheet metal (foil?) they use, especially the stainless is unbelievably
sharp on the inner edges.
 
W

William Sommerwerck

Jan 1, 1970
0
"Cydrome Leader" wrote in message
They are unsurpassed for stuff like frozen burritos or fresh broccoli.

And they're perfect for bacon. The microwave oven is the bachelor's friend.
 
C

Cydrome Leader

Jan 1, 1970
0
William Sommerwerck said:
"Cydrome Leader" wrote in message


And they're perfect for bacon. The microwave oven is the bachelor's friend.

I always found microwave bacon creepy.

di you have one of those weird "browning dishes" with the metal oxide
coating?
 
W

William Sommerwerck

Jan 1, 1970
0
And they're perfect for bacon. The microwave oven
I always found microwave bacon creepy.

You mean it moves?

You're probably not cooking it enough. You can "blast" it in a microwave
without burning, if you so desire.

Did you have one of those weird "browning dishes"
with the metal oxide coating?

No, I never did. Are they still made?
 
C

Cydrome Leader

Jan 1, 1970
0
Ian Field said:
VCRs were just as bad before they started making *EVERYTHING* out of
plastic.

yeah- within the past month I cut myself on a circa 2000 hitachi VCR from
a storage room. I popped the cover to check the rubber parts which are
actually intact, and the takeup torque is still good.

I wonder who set the trend of "let's save money and leave sheared edges
razor sharp" on stuff like that. They need a solid punch to the face, over
and over again.
 
C

Cydrome Leader

Jan 1, 1970
0
William Sommerwerck said:
You mean it moves?

You're probably not cooking it enough. You can "blast" it in a microwave
without burning, if you so desire.



No, I never did. Are they still made?

nope, and they're expensive on ebay.

I don't want one, but it would be fun to play with for about 10 minutes
I'm sure.

frozen potpies have paper bowls now instead of foil that will brown stuff,
sort of like whatever the stuff is inside a bag of microwave popcorn.
 
T

Trevor Wilson

Jan 1, 1970
0
And what gave you the idea of calling the voltage doubler charge-pump
cap; a "filter cap"?

**Pedant.

I will say once more:

I did NOT say "mains cap", despite your mis-reading of my words.

You can back-track all you wish. The meaning of my words is clear enough
to any sane person.
 
W

William Sommerwerck

Jan 1, 1970
0
I may have to spend the dollar on a potpie to take a look
at the bowl. I don't recall them looking or feeling all that
special, but it was fascinating that they did work.

They're best-known for their inclusion with Hot Pockets, but I find they don't
work that well -- probably because the sleeve surrounds the Pocket too closely
to allow moisture to easily escape. I generally start Hot Pockets bare in the
microwave, then crisp them in the toaster oven.
 
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