Digest for sci.electronics.repair@googlegroups.com - 25 updates in 9 topics

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Tim Schwartz <tim@bristolnj.com>: Oct 24 11:43AM -0400

On 10/23/2014 1:23 PM, Arfa Daily wrote:
> is ?
 
> TIA
 
> Arfa
 
Hi,
 
Found this link to an owner's manual of the MKII version:
 
http://images.thomann.de/pics/prod/195950_manual_eng.pdf
 
The last page as an address and a web address.:
 
http://www.thomann.de/gb/index.html?sid=aaf669a1b37cdccc73575203df1d90a2
 
Hope this helps,
Tim
Bristol Electronics
Ricardo Abreu <meus.registos.online@gmail.com>: Oct 24 07:28AM -0700

Hi,
 
 
I am troubleshooting my microwave oven and I need your help/hints.
(Yes, I know the risks of microwave oven's troubleshooting, I know the security rules and this is not the first oven I repair with your aid. :)
 
Problem is everything tests OK as you can see below (I am posting all the tests and measurements I made) but still no heat.
 
I must also state my test and measurement gear is a regular DMM, a HV capacitor discharging resistor string and my brain cells (at least those that survived the first years of parenting).
 
 
Make: LG
Model: MG-4324B
Type: Microwave oven
 
Symptoms: No microwave heating (everything else is fine). No reduced performance was noticed before failing.
 
Troubleshoot done so far:
 
HV transformer:
- AC mains DOES reach the primary winding while entering cooking cycle;
- No open winding;
- Resistance of primary winding: under 1 ohm;
- Resistance of 3.3V winding: under 1 ohm;
- Resistance of HV winding: 147 ohm;
- Voltage of 3.3V winding: 3.3V open, 2.8V loaded with magnetron's filament (HV disconnected);
 
Magnetron:
- Resistance between cathode/filament and anode/case: above 40 Mohm;
- Filament resistance: under 1 ohm
- Voltage at the filament: 2.8V (HV disconnected);
 
Diode:
- Tested good, forward voltage drop: 8V;
 
HV capacitor, marked 1.05uF +/-3% with internal bleeding resistor:
- Capacitance: 1.027uF;
- DC resistance (after transient): slightly above 1 Mohm or 4 Mohm (depending on how the DMM probes are connected);
 
Connections and wires:
- Tested and revised, all OK;
 
 
Any hints besides having a poltergeist inside the oven palying tricks on me?
Please?
 
Ricardo
Cydrome Leader <presence@MUNGEpanix.com>: Oct 24 03:42PM


> Any hints besides having a poltergeist inside the oven palying tricks on me?
> Please?
 
> Ricardo
 
That's some pretty thorough testing you've done so far, especially with
testing the filament winding open and under load. It think it's safe to
say the filament is good, and either the HV section has an issue or the
magnetron is just bad.
 
Testing the HV part is a little trickier. Do you have a way to safely test
the HV output from the doubler? If not, just skip this.
 
Next step would be swap parts, starting with the cheap ones. Swap the
cap with a new or known good one, then try the diode. If that doesn't
help, you probably have a bad magnetron, which may or may not be worth
replacing.
 
This has some pointers, which you've probably seen already
 
http://www.repairfaq.org/REPAIR/F_micfaq5.html#MICFAQ_001
 
It's a good doc for learning the concepts or experimenting at home, but
sort of pointless for real repair work, where speed matters. For example,
in a real shop, nobody takes the time to build a test jig for diodes. That
would cost more than just replacing it, even if that's not the problem.
Tapping into the filament with resistors seems weird too, since most
places have a current meter, and if you're confirmed the HV section is
good anyways, there's nothing left to replace but the magnetron, so
proving that the filament resistance is 4% out of spec doesn't even
accomplish anything anyways.
richard <f6ceedb9c75b52f7fcc0a55cf0cfbf5d_993@example.com>: Oct 21 01:37AM

the power beats two times faster than the opc light
 
--
Jeff Liebermann <jeffl@cruzio.com>: Oct 20 07:38PM -0700

On Tue, 21 Oct 2014 01:37:02 +0000, richard
 
>the power beats two times faster than the opc light
 
Beating on the TV isn't going to fix it.
Maybe a reset will help:
<http://technology.blurtit.com/624217/the-power-light-and-the-opc-light-blink-in-a-pattern-on-my-sharp-aquos-42-inch-lcd-it>
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
vjp2.at@at.BioStrategist.dot.dot.com: Oct 20 08:02PM

I had long figured I would have to pull a line from my phone nexus to near
the fuse box to connect to fiber modem. Phone nexus is in laundry room which
has plenty of power. Someone told me I can just plug in the fiber modem in
the laundry (and HVAC) room, which also conveniently has conduits with wires
going in and out of the house that I can bring the fiber line into. I know
installers just love to prove they can drill though just about any wall, but
I'm really no that keen about letting them.
 
 
- = -
Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist
http://www.panix.com/~vjp2/vasos.htm
---{Nothing herein constitutes advice. Everything fully disclaimed.}---
[Homeland Security means private firearms not lazy obstructive guards]
[Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos]
Jerry Peters <jerry@example.invalid>: Oct 19 07:58PM

> insulating "jacket" on the outside of the heater. A thermal
> insulating plastic layer between the water and the steel tank should
> improve efficiency.
 
I was discussing a *gas* HWH, where you do want the heat from the
burner to be conducted through the tank to the water.
 
> have stiffening ribs, which would allow the use of thinner steel. I
> guess(tm) stiffening might interfere with the necessary flexing of the
> tank with temperature.
 
I was thinking of the hot spots you could get with a gas HWH if the
plastic isn't in complete contact with the tank.
 
Stormin Mormon <cayoung61@hotmail.com>: Oct 19 05:35PM -0400

On 10/19/2014 12:57 PM, micky wrote:
> other, to their respective schools, but 2 years ago a big tree fell down
> blocking the path, with no good way to go around it, and now only one or
> two kids use it. ).
 
Center posted, like yours.
Someone should fine the HOA for the uncleared
tree. Yes, I've heard about HOA and towing
cars, seems to be a major passion of theirs.
I don't remember the details, but I do know
some folks who were visiting out of town. The
folks said fine to park in front of the house
while you stay over night. Car missing in Am,
$130 plus tow bill.
 
--
.
Christopher A. Young
Learn about Jesus
www.lds.org
.
josephkk <joseph_barrett@sbcglobal.net>: Oct 19 03:14PM -0700

On Sat, 18 Oct 2014 13:56:45 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
 
>warmer than the ambient air, you're wasting energy heating that
>atmosphere instead of the water. Same with a refrigerator. If the
>case of the fridge is colder than ambient, you're cooling the kitchen.
 
No. Refrigerators always heat the kitchen, they have condensers as well
and ALL the heat removed from the interior and the operating losses are
added to the room heat.
 
?-)
micky <NONONOmisc07@bigfoot.com>: Oct 19 09:15PM -0400

On Sun, 19 Oct 2014 17:35:42 -0400, Stormin Mormon
 
>Center posted, like yours.
>Someone should fine the HOA for the uncleared
>tree.
 
LOL. I hope not. I liked the kids and didn't mind them walking by,
but I'm happy the tree blocks their path. One or two of them would
ride their bikes on the grass, at least one of them even when the ground
was wet. One rider did about 10 times as much damage as one walker, and
one rider when it was wet did about 100 or 1000 times as much damage.
 
Anyhow, the land beyond mine is owned by Warren Buffett. I just learned
this a while back when the developer-apparent of a small old farm nearby
talked about who he dealt with concerining drainage from his property to
the stream. Well, he didnt deal with Buffet but with someone from his
company, maybe MidAmerican Energy Holdings Company's HomeServices of
America.
 
> Yes, I've heard about HOA and towing
>cars, seems to be a major passion of theirs.
 
Oh, yeah. They'd tow away your house, if they could.
 
>folks said fine to park in front of the house
>while you stay over night. Car missing in Am,
>$130 plus tow bill.
 
Darn.
Stormin Mormon <cayoung61@hotmail.com>: Oct 20 04:54AM -0400

On 10/20/2014 12:00 AM, Jeff Liebermann wrote:
> back and replaced it with one that had more insulation, which worked
> as expected. Since then, I've seen a few others that were cold to the
> touch.
 
Eventually, the guys at church will use a couple more
of the flood lights that are as bright as a "real"
one. I'll try and take home one of the boxes. Will
let you know what brand and model and so on.
--
.
Christopher A. Young
Learn about Jesus
www.lds.org
.
"Mr. Man-wai Chang" <toylet.toylet@gmail.com>: Oct 20 07:00PM +0800

On 13/10/14 3:53 AM, Bob F wrote:
> micky wrote:
>> Can an LED floodlight possibly be as bright as a real floodlight?
 
> The city street lights on my block are now LEDs, and they are plenty bright.
 
Came across an interesting article:
 
Your eco-friendly LED lights are drawing an awful lot more moths
http://www.engadget.com/2014/10/17/led-lights-drawing-more-insects/?a_dgi=aolshare_twitter
 
--
@~@ Remain silent. Nothing from soldiers and magicians is real!
/ v \ Simplicity is Beauty! May the Force and farces be with you!
/( _ )\ (Fedora 19 i686) Linux 3.14.22-100.fc19.i686
^ ^ 18:54:03 up 1 min 0 users load average: 0.21 0.13 0.05
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_pubsvc/page_socsecu/sub_addressesa
vjp2.at@at.BioStrategist.dot.dot.com: Oct 20 07:56PM

Eventually they should be. Right now they waste energy (produces heat but
not enough light) with transforming. I understand they will be doing pure
transistor voltage clipping which should be a heck of a lot more efficient
and produce fewer heat issues. This from asking dumb questions at trade shows
and fully understanding the folks at the booths might not really know. I have
a few 200W incandescents at home and haven't quite been able to replace
them. Then again I'm just a Chem Engr who took two oblig EE courses and grew
up with two vaccuum-tube-educated (photoypesetting and avionics) EE uncles.
 
- = -
Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist
http://www.panix.com/~vjp2/vasos.htm
---{Nothing herein constitutes advice. Everything fully disclaimed.}---
[Homeland Security means private firearms not lazy obstructive guards]
[Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos]
vjp2.at@at.BioStrategist.dot.dot.com: Oct 20 07:47PM

How do these work? (I generally believe it has some sort of Piezoelectric generator)
 
What if it stopped (I didn't use it for a few days)?
 
Does it have any battery which after a few years needs replacement?
 
Any chance I can find out what battery Curren M8039B uses so I only open it once?
 
And see what's inside (schematics) before I risk breaking it?
 
much obliged
 
(I was once at a lecture where someone used a piezo generator with a device
that created eddies in forest fires so they could call in the fire on a
cellular network without battery or wired power. I thought it was so cool I
found this ten buck watch that worked that way.)
 
- = -
Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist
http://www.panix.com/~vjp2/vasos.htm
---{Nothing herein constitutes advice. Everything fully disclaimed.}---
[Homeland Security means private firearms not lazy obstructive guards]
[Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos]
josephkk <joseph_barrett@sbcglobal.net>: Oct 19 05:26PM -0700

On Fri, 17 Oct 2014 22:13:09 +0100, "Gareth Magennis"
 
>Gosh, I am cross tonight. Must be the wine.
 
>Gareth.
 
In vino veritas.
 
?-)
"Michael A. Terrell" <mike.terrell@earthlink.net>: Oct 20 12:36AM -0400

"Mr. Man-wai Chang" wrote:
 
> I have yet to see a blueprint that generates electricity from nuclear
> fusion. I would expect a fusion-powered steamer. :)
 
 
Blueprints don't produce electricity.
 
 
--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
N_Cook <diverse@tcp.co.uk>: Oct 20 07:59AM +0100

On 20/10/2014 05:36, Michael A. Terrell wrote:
 
>> I have yet to see a blueprint that generates electricity from nuclear
>> fusion. I would expect a fusion-powered steamer. :)
 
> Blueprints don't produce electricity.
 
Perhaps just an overactive PR dept, making sure the name L-M is in the
media, near enough same story from 18 months ago
http://www.fusenet.eu/node/400
"Michael A. Terrell" <mike.terrell@earthlink.net>: Oct 20 11:36AM -0400

N_Cook wrote:
 
> Perhaps just an overactive PR dept, making sure the name L-M is in the
> media, near enough same story from 18 months ago
> http://www.fusenet.eu/node/400
 
 
Lockheed-Martin doesn't need PR. They are a large defense contractor
that does basic research as well. They have facilities scattered all
over the US. There is one not far from here that did sat terminals for
government agencies. They build planes, weapons systems and other items
for multiple countries.
 
 
--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
josephkk <joseph_barrett@sbcglobal.net>: Oct 19 04:27PM -0700

On Thu, 16 Oct 2014 10:33:22 -0400, "Michael A. Terrell"
>which was slow and expensive.
 
> The production line was developed to build rifles for the U.S. Army,
>with interchangable parts.
 
Interchangable parts (specifically for guns) is at least 50 years older
than H. Fords production line for cars.
 
?-)
josephkk <joseph_barrett@sbcglobal.net>: Oct 19 04:31PM -0700

>> think it's Nobel-worthy.
 
>Fair point, certainly wrt yellow or green or orange but blue was the
>key to getting to white LED-light, a quantum leap ;-)
 
No, not a quantum leap. Certainly not compared to the initial LED.
 
?-)
josephkk <joseph_barrett@sbcglobal.net>: Oct 19 04:38PM -0700

>can be powered off a battery and solar cells to recharge it.
 
>They are looking at the big picture.
 
> Michael
 
Well, sort of. The Nobel is a political award, as evidenced by giving one
to Yassir Arafat an aging ex-terrorist. The blue improvement was
incremental compared to making LEDs the first time. Also just look at
what body controls the awards.
 
?-)
"Arfa Daily" <arfa.daily@ntlworld.com>: Oct 20 01:31AM +0100

"josephkk" <joseph_barrett@sbcglobal.net> wrote in message
news:uci84ap76emjltejv7h6071u3a5pkus7a5@4ax.com...
>>key to getting to white LED-light, a quantum leap ;-)
 
> No, not a quantum leap. Certainly not compared to the initial LED.
 
> ?-)
 
I rather think it was actually. The principle of the LED had been known for
a long time, and producing the first commercially successful ones was more a
case of tweaking and refining than 'real' innovation. Producing the other
long and medium wavelength colours such as yellow and green was a variation
on a theme. Producing a successful blue LED with a useable level of output
was rather more difficult and defeated those who were trying for many years.
I can remember the first LEDs appearing, and yes, for sure, they were an
interesting component that made it possible to produce low voltage numeric
displays and panel indicators, and the other colours that followed improved
the versatility in that respect, but the real 'holy grail' was the blue one
which, as Mr Cook suggests, was the final puzzle piece to open up the way
for full colour video display panels, and white light for space lighting ...
 
Arfa
"William Sommerwerck" <grizzledgeezer@comcast.net>: Oct 19 06:35PM -0700

Isn't the real question whether blue LEDs were the result of engineering
breakthroughs, or fundamental scientific research?
 
Based on what I read a few months ago about the dogged work of the man who
made the breakthrough, I'm inclined to go with the former, and say that this
work was not worthy of a Nobel for physics.
"Michael A. Terrell" <mike.terrell@earthlink.net>: Oct 20 12:32AM -0400

josephkk wrote:
> >with interchangable parts.
 
> Interchangable parts (specifically for guns) is at least 50 years older
> than H. Fords production line for cars.
 
 
Yes, but he was the first to apply that to building cars to bring the
price down enough for thee average working man.
 
 
--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
"Michael A. Terrell" <mike.terrell@earthlink.net>: Oct 20 12:31AM -0400

"Ron D." wrote:
 
> I generally like the Term-a-nut process for wiring. One white, one black and one green. The parallel connections don't rely on the screw terminal pigtails.
 
> Seasoned electricians pigtail the connections in the box with a wirnut.
 
> The term-a-nuts I think can be purchased in stranded or solid. Not sure though. I use the stranded type.
 
 
Are they legal in every jurisdiction? A lot of things aren't allowed
under local codes.
 
 
--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
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