sci.electronics.repair@googlegroups.com

Today's topics:

* What's wrong with high humidity? - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/01fadf8338789066?hl=en
* IEC 705-88 Microwave Oven power measurement???what is it? - 2 messages, 2
authors
http://groups.google.com/group/sci.electronics.repair/t/ea891b75f315fec8?hl=en
* AA-sized conductor (fake battery) wanted - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/33083a4b1e46ccc0?hl=en
* Microwave timer/clock 4 digit 7-segmnt display is out. Timer works fine. - 2
messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/f9d37ccd9c82199e?hl=en
* Magnifying glass for smd components - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/152fab9f5593225c?hl=en

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TOPIC: What's wrong with high humidity?
http://groups.google.com/group/sci.electronics.repair/t/01fadf8338789066?hl=en
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== 1 of 1 ==
Date: Fri, Jan 14 2011 9:42 pm
From: mm

On Tue, 11 Jan 2011 09:48:33 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>On Tue, 11 Jan 2011 02:22:59 -0500, "Michael A. Terrell"
><mike.terrell@earthlink.net> wrote:
>
>>mm wrote:
>>>
>>> To sci.electronics.repair
>>>
>>> Most electronic things are rated wrt humidity, but it never mattered
>>> to me before. Now something I might actually want** has a maximum
>>> operating humidity of 80%, and I am pretty sure it gets that humid
>>> here sometimes. (I rarely use my AC and it's broken now anyhow.)
>>>
>>> So what's wrong with high humidity? What won't it do, and why? I've
>>> had high humidity all my life for part of the summer, and I don't
>>> remember anything not working.
>
>> Condensation when the temperature drops.

Thanks.
>
>Yep. Also a tendency to increase leakage in hydroscopic and
>hydrophilic components such as some film capacitors, phenolic circuit
>boards, paper insulators, paper speaker grills, some microphone
>elements, and some carbon comp resistors. I designed marine radios
>for too many years and water absorption was a serious consideration.
>We even designed most radios with vertically mounted boards to prevent
>condensation from puddling. In humid climates, there was the added
>bonus of mold and mildew. I've had to clean out radios that looked
>like a biology experiement gone wild.

Thanks also.

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TOPIC: IEC 705-88 Microwave Oven power measurement???what is it?
http://groups.google.com/group/sci.electronics.repair/t/ea891b75f315fec8?hl=en
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== 1 of 2 ==
Date: Fri, Jan 14 2011 9:46 pm
From: "Wild_Bill"

Ohhhh.. you mean leakage.

--
Cheers,
WB
.............

"mike" <spamme9@gmail.com> wrote in message
news:igr3j9$mpu$1@news.eternal-september.org...
> IEC 705-88 Microwave Oven power measurement???what is it?
>
> What is the IEC 705-88 procedure for measuring microwave
> oven power output?
>
> I've googled myself silly. Only thing I found is one
> Amazon book excerpt. Starts describing the procedure,
> but deletes two pages out of the middle...please insert
> $200 to read the entire article...thankyouverymuch.
>
> I AM NOT ASKING HOW TO MEASURE MICROWAVE OVEN POWER OUTPUT.
> I AM NOT ASKING HOW TO MEASURE MICROWAVE OVEN POWER OUTPUT
> I AM NOT ASKING HOW TO MEASURE MICROWAVE OVEN POWER OUTPUT
> I AM NOT ASKING HOW TO MEASURE MICROWAVE OVEN POWER OUTPUT
> I AM NOT ASKING HOW TO MEASURE MICROWAVE OVEN POWER OUTPUT
>
> Maybe if I write it 5 times, the message will get through.
>
> I know how to measure it with a thermometer and a stopwatch.
>
> What I'm asking is...
> When I go to the store and look at the numbers written
> on the box that state the power output per iec705,
> what do THEY mean...and how does that relate to what I'm
> gonna find when I use my stopwatch and thermometer.
>
> One more time.
> I AM NOT ASKING HOW TO MEASURE MICROWAVE OVEN POWER OUTPUT.
> I'm asking how IEC705 measures power output.
>
> Thanks, mike

== 2 of 2 ==
Date: Fri, Jan 14 2011 9:56 pm
From: "Phil Allison"

"mike"
>
> IEC 705-88 Microwave Oven power measurement???what is it?
>

** Very secret & very mysterious .....

> What is the IEC 705-88 procedure for measuring microwave
> oven power output?
>
> I've googled myself silly. Only thing I found is one
> Amazon book excerpt. Starts describing the procedure,
> but deletes two pages out of the middle...please insert
> $200 to read the entire article...thankyouverymuch.
>
> I AM NOT ASKING HOW TO MEASURE MICROWAVE OVEN POWER OUTPUT.
> I AM NOT ASKING HOW TO MEASURE MICROWAVE OVEN POWER OUTPUT
> I AM NOT ASKING HOW TO MEASURE MICROWAVE OVEN POWER OUTPUT
> I AM NOT ASKING HOW TO MEASURE MICROWAVE OVEN POWER OUTPUT
> I AM NOT ASKING HOW TO MEASURE MICROWAVE OVEN POWER OUTPUT
>
> Maybe if I write it 5 times, the message will get through.
>
> I know how to measure it with a thermometer and a stopwatch.
>
> What I'm asking is...
> When I go to the store and look at the numbers written
> on the box that state the power output per iec705,
> what do THEY mean...and how does that relate to what I'm
> gonna find when I use my stopwatch and thermometer.

** All references on the net suggest that the IEC method uses a " formula "
to compute the effective microwave power level on the basis of a specified
test.

The dish of water and a thermometer method is fairly obviously not
recise - there is the heat stored in the dish itself and lost when water
vapour that is formed during the test.

PLUS heat energy is lost due to radiation and conduction from the dish as it
rises above ambient.

Seems the IEC method compensates for all these factors and you wind up with
a figure that is about 10 to 15 % more than the imprecise method.

..... Phil

==============================================================================
TOPIC: AA-sized conductor (fake battery) wanted
http://groups.google.com/group/sci.electronics.repair/t/33083a4b1e46ccc0?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Jan 14 2011 9:57 pm
From: "Wild_Bill"

The dowel and wire would be the most easily fabricated/accomplished for most
handy folks, I think.
If some cells are arranged end-to-end in the equipment's battery holder,
placing the dowel version between 2 other cells would eliminate the need for
a more sophisticated top and bottom terminal, which some battery holders
actually require.

Additionally, it's about as lightweight as can be, and durable (won't
collapse or leak, etc).

--
Cheers,
WB
.............

"Jim Yanik" <jyanik@abuse.gov> wrote in message
news:Xns9E6DD3D6CE067jyaniklocalnetcom@216.168.3.44...
>
> Better to just cut a dowel to size,cut a slot for a wire from end to
> end,fold over the ends,maybe epoxy in place.
>
> Cheap,easy. follows the KISS principle.
>
> --
> Jim Yanik
> jyanik
> at
> localnet
> dot com

==============================================================================
TOPIC: Microwave timer/clock 4 digit 7-segmnt display is out. Timer works fine.

http://groups.google.com/group/sci.electronics.repair/t/f9d37ccd9c82199e?hl=en
==============================================================================

== 1 of 2 ==
Date: Fri, Jan 14 2011 11:52 pm
From: "Angelo Campanella"

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:igmsb5$ifv$1@news.eternal-september.org...
> Can you view the board enough to count the pins on each of the non-display
> electronic chips?

Have to unscrew the bezel allen screws again. in a few days..

Ange

== 2 of 2 ==
Date: Sat, Jan 15 2011 12:20 am
From: "Angelo Campanella"

"Geo" <hw9j-s5hw@dea.spamcon.org> wrote in message
news:cfsti651b4s20lm4ge8tstl36nbnhfiocu@4ax.com...
> If you look at this page:-
> http://www.decodesystems.com/old-displays.html

Seems to be near what I have.

> There are two gifs from an HP appnote.
> They shows suitable multiplexing circuits.
> It is possible that your circuit has stopped multiplexing so only single
> segments permanently on.
> May be missing a clock signal.

I'm an old discrete component and vacuum tube guy.

I presume that "strobe" means hat there is only one driver, the SN7447
which is the only segment feeder, that the digit switched on at the moment
by the strobe signal will take segment current and light up.

The current comes from the 7447, whatever of the 7 lines is to run to
make the number of the instant.

In my uwave, only E segment is lit and the E of all 4 digits are on all
the time. No other segments of all 4 digits ever light. Well, actually the
4 of digit 4 is lighting every time its turn comes in the countdown. Perhaps
that digit is more sensitive.

One thing for me to look at is the health of the seven 47 ohm resistors.

Another is to check the + voltage supply. Do I expect 5 volts or some
higher value? The two raw dc supplies are 10 or 20 volts (the filter
capacitors gave away their location.)

Ange

==============================================================================
TOPIC: Magnifying glass for smd components
http://groups.google.com/group/sci.electronics.repair/t/152fab9f5593225c?hl=en
==============================================================================

== 1 of 1 ==
Date: Sat, Jan 15 2011 12:40 am
From: "N_Cook"

Jack00 <SPal508596@aol.com> wrote in message
news:cb4d689d-d0b4-42ae-a5dc-1b288aa86ce4@a10g2000vby.googlegroups.com...
> Does anyone know a magnifying glass that can be used for surface
> mounted components as they are too small to see with a standard
> magnifying glass. And also which amplification ie 2x 5x 10x 20x
>
> Cheers

I usually use one of these
http://www.growhubhydroponics.com/images/Pocket_Microscope.jpg
with the transparent bit slid off. It has x30 and a goodly amount of
"headroom" between SMD and the lens.
If SMD lies right next to a large/deep lump on the pcb then a kids
microscope barrel with a large notch ground into the objective end, actually
ground into the plastic lens,
originally used for viewing VCR heads.

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