dead microwave
james
When plugged in, no clock is displayed. Nothing. No response to any buttons.
No lights, no fan, no sound.
It failed gradually. Starting from a few buttons that didn't work, then
this.
It is a combo microwave/range hood. I opened up the panel/keyboard. There's
a layer of grease on the circult board, and some grease droplets dangling on
wires and connectors. Some greenish(!) grease drips out of connectors. Could
the grease cause the connectors to fail?
I found on the internet a parts and schematic PDF for this model.
Unfortunately, the schematic shows everything (relays, transformers, lights,
fuses, magnetron, motors) but the controller board. Yet the controller board
is where I want to start debugging since it houses the LCD display and hooks
up to the keypad. Does anyone know where to get the controller board's
schematic?
BTW, there's a note inside saying "this device should not be serviced by a
do-it-yourself repair person". I could understand if it says "this device
should be serviced only by a qualified person". But why get personal?
Meat Plow
> Frigidaire, Professional Series PLMV169DCD
>
> When plugged in, no clock is displayed. Nothing. No response to any
> buttons. No lights, no fan, no sound.
> It failed gradually. Starting from a few buttons that didn't work, then
> this.
Uh Huh.
> It is a combo microwave/range hood. I opened up the panel/keyboard.
> There's a layer of grease on the circult board, and some grease droplets
> dangling on wires and connectors. Some greenish(!) grease drips out of
> connectors. Could the grease cause the connectors to fail?
Yep
> I found on the internet a parts and schematic PDF for this model.
> Unfortunately, the schematic shows everything (relays, transformers,
> lights, fuses, magnetron, motors) but the controller board. Yet the
> controller board is where I want to start debugging since it houses the
> LCD display and hooks up to the keypad. Does anyone know where to get
> the controller board's schematic?
Controllers are usually replaced not serviced.
> BTW, there's a note inside saying "this device should not be serviced by
> a do-it-yourself repair person". I could understand if it says "this
> device should be serviced only by a qualified person". But why get
> personal?
Because your health depends on you knowing what you are doing. What price
are you willing to see yourself and others possibly pay for a more
friendly message?
--
Live Fast, Die Young and Leave a Pretty Corpse
William Sommerwerck
> serviced by a do-it-yourself repair person". I could understand
> if it says "this device should be serviced only by a qualified
> person". But why get personal?
"I don't get no respect!"
Why not start by simply cleaning up everything? The only thing you might
have to worry about is electrostatic discharge damaging the controller or
other electronic components.
hrho...@att.net
wrote:
I would suggest some naptha and a soft brush to dissolve the grease
and clean the board. Do NOT use soap and /or water!!!! After
everything looks clean and nice, let it sit overnoght before you plug
it back in. That gives time for things to dry out reasonably well.
Arfa Daily
<hrho...@att.net> wrote in message
news:3c5b4d13-bdf2-45ef...@l20g2000yqm.googlegroups.com...
Surely, the most fundamental first move is to take a meter to the power
supply, and see if there is at least some supply to the system control micro
etc ? The fact that it's covered in grease may well be neither here nor
there as far as the fault goes. Oils and greases are not known for being
particularly conductive or corrosive. Dead is a positive problem, and one to
which basic faultfinding techniques should be first applied, before going
off on an 'if-then-maybe' exercise ...
Arfa
William Sommerwerck
> supply, and see if there is at least some supply to the system control
> micro etc ? The fact that it's covered in grease may well be neither here
> nor there as far as the fault goes. Oils and greases are not known for
> being particularly conductive or corrosive. Dead is a positive problem,
> and one to which basic faultfinding techniques should be first applied,
> before going off on an 'if-then-maybe' exercise ...
I'd normally agree, but the fact the unit /slowly/ declined suggests that
something other than a voltage loss is going on.
Of course, it takes just a few seconds to check the voltages. Couldn't hurt.
Cydrome Leader
That is an odd warning. Microwaves should just state "you will die if you
open this, even if it's unplugged.
Arfa Daily
"William Sommerwerck" <grizzle...@comcast.net> wrote in message
news:i9aetj$8ke$1...@news.eternal-september.org...
>> Surely, the most fundamental first move is to take a meter to the power
>> supply, and see if there is at least some supply to the system control
>> micro etc ? The fact that it's covered in grease may well be neither here
>> nor there as far as the fault goes. Oils and greases are not known for
>> being particularly conductive or corrosive. Dead is a positive problem,
>> and one to which basic faultfinding techniques should be first applied,
>> before going off on an 'if-then-maybe' exercise ...
>
> I'd normally agree, but the fact the unit /slowly/ declined suggests that
> something other than a voltage loss is going on.
Well, not really. Analogue power supplies, such as the ones in microwave
ovens usually are, will die gracefully as a result of bad electrolytics
getting worse.
Arfa
William Sommerwerck
>> that something other than a voltage loss is going on.
> Well, not really. Analogue power supplies, such as the ones in
> microwave ovens usually are, will die gracefully as a result of bad
> electrolytics getting worse.
I've never seen this, but I sure don't know everything. Anyhow, what about
the fact that some buttons "failed" before others? (That's a rhetorical
question.)
Arfa Daily
"William Sommerwerck" <grizzle...@comcast.net> wrote in message
news:i9c0fe$h4n$1...@news.eternal-september.org...
Understood a rhet question, but I guess it still might need an answer for
others following the thread.
If a supply that's feeding a logic device such as a microcontroller becomes
'dirty' - that's either with excessive ripple from an analogue supply, or
hash from a switch mode supply, and both cases potentially caused by a
failing filter cap, - then operation of the micro can become 'flaky'. This
can take the form of odd / unreliable behaviour, incorrect reset at power
up, incorrect operation of any connected displays, and wrong operation of
connected peripherals such as keypads, fault sensors etc. This is
particularly true of devices which use A-D converter inputs with a ladder of
resistors connected between buttons, to sense which button has been pressed,
although it can also occur with matrix driven / sensed keypads.
Arfa
Meat Plow
The microwave as I understood was above a stove and was probably cleaned
frequently because of its location. I've seen many control panels
permanently damaged by cleaning fluids on not only microwaves but also
other home appliances and electronics. This fact can certainly account
for button failure.
Arfa Daily
"Meat Plow" <mhy...@yahoo.com> wrote in message
news:pan.2010.10...@lmao.lol.lol...
Agreed. I was just thinking of a scenario that would account for both
progressive failure of buttons, and then ultimately (apparent) total failure
of the unit to operate at all.
Arfa
Meat Plow
Total failure as in front panel function could easily result from
cleaning fluids, corrosive cooking vapors, condensation etc..
I don't recall if the OP mentioned the interior light working when the
door was opened.
hrho...@att.net
> On Sat, 16 Oct 2010 14:41:02 +0100, Arfa Daily wrote:
>
> - Show quoted text -
Excellent point about the interior door/light, that is usually a
combination of microswitches and a relay contact from the controller
so the light goes on if the door is opened or if it is cooking.
Jim Yanik
news:PXhuo.1843$jH7....@newsfe29.ams2:
grease infiltration into the keypad could be the first problem,and then
grease making a conductive path and the HV shorting out and blowing the
line fuse.
I finally "retired" my 30 year old,$350USD Sharp MW,replaced it with a $99
GE from Wal-Mart;1.8Cu.Ft.,1100W.
Had to return the first one,the turntable didn't turn....
then I realized how much the power had dropped on the older 700W Sharp. ;-)
I don't expect the GE to last half as long as the Sharp did.
--
Jim Yanik
jyanik
at
localnet
dot com
Klaatu
news:Xns9E138A1338FF3...@216.168.3.44...
If it has GE on the front, you'll be lucky to make it past the first year.
ESPECIALLY if you bought it at Wal-Mart.
William Sommerwerck
My GE over-the-cooktop microwave is 11 years old, gets near-daily use, and
is a-working still.
Jeffrey Angus
That's because it IS 11 years old.
The reference was for the new ones being sold at Wal=Mart.
Jeff
William Sommerwerck
>>> the first year.
>> My GE over-the-cooktop microwave is 11 years old,
>> gets near-daily use, and is a-working still.
> That's because it IS 11 years old.
> The reference was for the new ones being sold at Wal-Mart.
I still have one of the last made-in-the US Littons, which I can pull out if
the GE fails.
Does anyone make a really good, reliable microwave?
PS: There's a classic MAD spoof showing an Appalachian family (is that
sufficiently PC) around their washing machine, which has been converted for
alcohol production: "Our Mayjag is 18 years old, and it's a-working still!"
Meat Plow
1100 watt GE here. Now 6 years old, works good as new.
Jeff Liebermann
<mhy...@yahoo.com> wrote:
>Total failure as in front panel function could easily result from
>cleaning fluids, corrosive cooking vapors, condensation etc..
>I don't recall if the OP mentioned the interior light working when the
>door was opened.
I was once asked to look at a heavily used microwave oven at a local
residential facility. The description was similar, but the problem
was obvious on first inspection. Long finger nails punching through
the elastometric contact keyboard. Once the protective membrane on
the front panel is punctured, all manner of liquids and gasses can
cause damage. I've seen this problem other times, where the customer
doesn't want to admit that they damaged the front panel, or somehow
considers such damage as normal. It also applies to TV/hi-fi remote
controls, printer control panels, calculators, where easily damaged
flexible membranes are used in place of hard plastic buttons.
While grease is usually non-conductive, having any grease in the
various connectors will produce lousy connections. I suspect a good
cleaning, and a low grease diet, might restore the oven to normal
operation. The green crud (copper sulfate) does not necessarily
signal the demise of the wiring, unless it's extensive. I would not
replace any electronics until the keyboard and controller cards are
baptized in solvent. It would also be interesting to determine how
the grease entered the area. Probably a mechanically mis-aligned
exhaust duct.
Opinions:
<http://www.epinions.com/reviews/Frigidaire_PLMV169DC_Stainless_Steel_Microwave_Oven>
This one is interesting:
<http://www.epinions.com/review/Frigidaire_PLMV169DC_Stainless_Steel_Microwave_Oven/content_392811679364>
The Bottom Line: Despite the top-flight brand name, attractive
styling, and high price tag, this microwave is unreliable and
extremely difficult to clean.
Drivel: US DoE can't figure out how to measure microwave oven power
output.
<http://www.federalregister.gov/articles/2010/07/22/2010-17773/energy-conservation-program-for-consumer-products-test-procedure-for-microwave-ovens-repeal-of>
Sigh.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
David
>power
>output.
><http://www.federalregister.gov/articles/2010/07/22/2010-17773/energy-conservation-program-for-consumer-products-test-procedure-for-microwave-ovens-repeal-of>
>Sigh.
>Jeff Liebermann je...@cruzio.com
Your tax dollars at work, Sigh^2.
David
Meat Plow
I've seen the corruption of membrane switch panels from users spraying
things like window cleaners directly on them. Without any punctures.
While talking to the customer I try to ask how they cleaned their stuff
without trying to point blame. People don't like to readily admit to the
over zealous spraying of cleaners that can and do eventually seep into
membrane panels. I cringed in horror once watching my girlfriend cleaning
my then 2 year old GE oven, She sprayed the front with copious amounts of
window cleaner. I told her from now on she was to lightly spray it on a
clean cloth first then wipe the membrane. On everything. Not too many
realize this is a serious problem unfortunately.
Fred McKenzie
Jeff Liebermann <je...@cruzio.com> wrote:
> Drivel: US DoE can't figure out how to measure microwave oven power
> output.
Jeff-
My impression is that the referenced article refers to efficiency, not
power output. It talks about such things as magnetron filament current
and warm-up time.
Somewhere on the web I found a procedure for measuring power. You heat
a liter of water for a certain amount of time, measuring temperature
before and after. Using a formula, temperature rise correlates to power
output.
I think such a procedure is basic, and don't see how it could be
challenged other than for "hot spots" in an oven. In my case, the oven
has a carousel to compensate.
My old 900 Watt Sharp microwave actually puts out 650 Watts according to
the procedure. I adjust cooking times meant for 1100 Watt units,
multiplying by 1100/650. The food appears to be getting the right
amount of heat.
An old Sharp "Half Pint" is rated for 450 Watts. The above procedure
agrees exactly.
Fred
Jeff Liebermann
wrote:
Yeah, it's really a tough problem. Never mind IEC-705 which has been
around since 1990.
<http://www1.eere.energy.gov/buildings/appliance_standards/residential/docs/krtp1003.txt>
Place about a liter of water in the oven. Measure temperature. Apply
power. Measure temperature again after a specific cooking time.
Power = (Volume_of_water) x (Temp_rise) x 4.1868 / (Cook_time)
4.1868 is joules/calorie (specific heat of water)
Power = Watts
Volume = Cubic centimeters or Milliliters
Temp rise = Celsius
Cooking time = Seconds
Every oven I've tested (6 ovens) with a liter flask and about a minute
runtime has resulted in measurements of 15% to 30% less than the rated
power. If a use more water and a longer runtime, even less (because
the magnetron decreases in RF output as it gets hot). This is not
because the manufacturers all lie, but because the IEC-705 standard
method generates inflated results for power output. This might also
offer a clue why the DoE can't seem to find a workable procedure that
produces the same results as IEC-705.
I've also measured the efficiency of these ovens. All are about 60%
(using the above test procedure).
Perhaps what's needed is a multi-million dollar research grant to
study methods of measuring microwave oven power output. However,
should such a study succeed, I'm certain the method will be ultra
complexicated and designed to sell plenty of specialized hardware and
certified testing labs. With luck, maybe even a bureaucracy to
oversee the muddle.
Hint: Don't use a big heavy Pyrex glass bowl as it becomes part of
the thermal mass and wrecks the results. Use thin chemistry glassware
or if really careful, light plastic bowls. A 10C to 20C temp rise is
sufficient. No need to boil the water. Don't leave the thermometer
inside the oven when running. Let the water temperature stabilize for
30 seconds or more at the end of a run as microwave heating is rather
uneven.
Dave Platt
William Sommerwerck <grizzle...@comcast.net> wrote:
>Does anyone make a really good, reliable microwave?
We had a Kenmore which had lasted us almost 20 years.
When it gave up the ghost, I replaced it with a Panasonic "inverter"
model... one of the higher-end consumer-grade microwaves. This died
early this year less than three years of service. Looking at the
consumer-grade microwaves available at the time gave me no confidence
at all.
I bought an Amana "medium volume commercial setting" model (ALD10T) as
a replacement. It's roughly twice the price of the better
consumer-grade type, but does seem to have a substantially better
build quality, and the magnetron has a 3-year warranty as opposed to 1
year (or less) for consumer-grade models. My hope is that it will
have a substantially longer lifetime than today's race-to-the-bottom
consumer junk. Biggest negative noted so far (from my wife'w point of
view) is that the fan continues to run for 30 seconds to a minute
after the cooking cycle is complete - this clears out the steam and
odors from inside the oven, but she hates the noise.
The companion model ALD10D has a mechanical timer and dial, and only a
single power setting... less to go wrong.
--
Dave Platt <dpl...@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
Jeff Liebermann
wrote:
>In article <throb6lgnkk4keed3...@4ax.com>,
> Jeff Liebermann <je...@cruzio.com> wrote:
>
>> Drivel: US DoE can't figure out how to measure microwave oven power
>> output.
>
>Jeff-
>
>My impression is that the referenced article refers to efficiency, not
>power output. It talks about such things as magnetron filament current
>and warm-up time.
Yep. I measure the power input to the microwave with a Kill-a-watt
power meter. The power output is using the calorimetric water heater
method. I can throw in defrost, pre-heat, warm-up, cool-down, and
such if you insist.
>Somewhere on the web I found a procedure for measuring power.
What was dropped was:
<http://www1.eere.energy.gov/buildings/appliance_standards/residential/docs/krtp1003.txt>
<http://www1.eere.energy.gov/buildings/appliance_standards/residential/pdfs/home_appl_micro_oven_tp_fr.pdf>
They're measuring "useful cooking energy" which is similar to the
exaggerated numbers produced by "peak music power" in hi-fi.
>You heat
>a liter of water for a certain amount of time, measuring temperature
>before and after. Using a formula, temperature rise correlates to power
>output.
<http://www.gallawa.com/microtech/output.html>
<http://www.ebsciences.com/papers/microwave_quality.htm>
<http://www.zyra.info/micropwr.htm>
>I think such a procedure is basic, and don't see how it could be
>challenged other than for "hot spots" in an oven. In my case, the oven
>has a carousel to compensate.
I was borrowing an FLIR i7 infrared camera to do some unrelated (and
paying) tests.
<http://www.flir.com/thermography/americas/us/content/?id=24072>
What got my attention was the rather bizarre pattern of heating on a
small pizza in the microwave oven. Of course, the carousel and
stirrer fan help reduce hot spots, but it still takes time for the
heat to move around in a liter of water.
>My old 900 Watt Sharp microwave actually puts out 650 Watts according to
>the procedure. I adjust cooking times meant for 1100 Watt units,
>multiplying by 1100/650. The food appears to be getting the right
>amount of heat.
My cheap junk Welbilt something oven claims 950 watts and delivers 800
watts.
>An old Sharp "Half Pint" is rated for 450 Watts. The above procedure
>agrees exactly.
That's because IEC-705 was designed to inflate the ratings. See first
paragraph at:
<http://www.gallawa.com/microtech/output.html>
Jeff Liebermann
wrote:
>Yeah, it's really a tough problem. Never mind IEC-705 which has been
>around since 1990.
><http://www1.eere.energy.gov/buildings/appliance_standards/residential/docs/krtp1003.txt>
New and improved IEC-705 is now IEC 60705:
<http://global.ihs.com/doc_detail.cfm?currency_code=USD&customer_id=2125482C3B0A&shopping_cart_id=282758232F4950244D595D58240A&rid=Z56&input_doc_number=iec%20705&mid=5280&input_doc_number=iec%20705&country_code=US&lang_code=ENGL&item_s_key=00133560&item_key_date=930931&input_doc_number=iec%20705&input_doc_title=&org_code=IEC>
For only $143, you too can learn how governments rate microwave ovens
or maybe P-IEC 60705 {Ed.3.2}
<http://www.iec.ch/cgi-bin/procgi.pl/www/iecwww.p?wwwlang=e&wwwprog=cat-det.p&progdb=db1&wartnum=035873>
<http://www.iecchallenge.net/cgi-bin/procgi.pl/www/iecwww.p?wwwlang=english&wwwprog=pro-det.p&progdb=db1&He=IEC&Pu=60705&Pa=&Se=&Am=1&Fr=&TR=&Ed=3>
for $170.