sci.electronics.repair - 18 new messages in 9 topics - digest

sci.electronics.repair
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Today's topics:

==============================================================================
TOPIC: LCD Desktop Monitor Fading to White, then Black
http://groups.google.com/group/sci.electronics.repair/t/2c04885c7b46754a?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, May 4 2010 9:12 pm
From: Jeff Liebermann

On Tue, 4 May 2010 20:15:46 -0700 (PDT), saber850 <saber850@yahoo.com>
wrote:

>> > >http://www.ccl-la.com/blog/index.php/samsung-214t-repair

>I opened the case and analyzed all the caps--none are bulging or
>leaking/oozing.

One small step... etc.

Look at the photos in:
<http://www.ccl-la.com/blog/index.php/samsung-214t-repair>
Do you see any bulging or leaks? Nope. Not all caps fail with
obvious physical evidence. That's where the ESR meter is used. You
can test the capacitors without removing them from the circuit.
Lacking that, just get some replacement caps, replace everything
listed in the article, and it should be back to working.

As for a better understanding of what's happening, it's difficult
enough to analyzer a circuit when all the parts are within normal
design limits. However, if you want to see what happens when you
insert a defective capacitor into the circuit, download a free copy of
LTSpice (formerly known as SwitcherCAD),
<http://www.linear.com/designtools/software/>
and buy a collection of SPICE switcher models:
<http://pagesperso-orange.fr/cbasso/Spice.htm>
<http://pagesperso-orange.fr/cbasso/Downloads/LTSpice/PWM%20Switch%20LTSpice.zip>
The author suggests you need the book to understand the models. I
agree.

Get the program working with a proper switching power supply. It
doesn't have to be exactly the same as the Samsung monitor. Then cram
in the equivalent of a bad capacitor, which would be a normal
capacitor, with the same capacitance value as on the label, but with
an added series resistance equal to about 2-5 times maximum ESR.
<http://members.ozemail.com.au/~bobpar/2003esrchart.txt>
<http://members.ozemail.com.au/~bobpar/graph1.gif>
<http://members.ozemail.com.au/~bobpar/graph2.gif>
<http://members.ozemail.com.au/~bobpar/graph3.gif>

A subtle hint is that with a switching power supply, the output
voltage almost never goes up when a component fails. It either goes
down, or massive amounts of high frequency ripple appears on the
output. How the rest of the LCD monitor responds to this is a bit of
a guess. Usually, it just shuts down, resulting in a black display.

Also, I forgot to caution you to *NOT* constantly power cycle the
monitor in an attempt to revive the circuit. It's bad enough having
the capacitors blow up. There's a chance that the associated
switching transistors will not appreciate the added load (which is
what's heating the capacitors) and blow up. For example, this loser
of a Dell monitor:
<http://www.ccl-la.com/blog/index.php/dell-e173fpb-17lcd-repair/>
usually takes out 6 xsistors, a diode, and anywhere between one and
eight electrolytics. I once tried to fix one, and didn't catch one of
the caps. Within a week, all 6 transistors were again blown.

Also, if you read the above instructions carefully, note that it
mentions resoldering the xformer leads. I do this whether it needs it
or not. What happens is that the xformers operate at about 40KHz(?).
Some of this 40KHz energy is transfered to the xformer leads,
resulting in cracked solder. It's very difficult to see without a
microscope. It was a problem with Tin-Lead solder but is really a
PITA with brittle ROHS Tin-Silver solder. The same thing can happen
at audio frequencies:
<http://www.clarkeaudio.com/nfinfo.htm>

Anyway, your next ordeal will be selecting the proper replacement
capacitors from the Digikey or Mouser online order pages. It's very
easy to pick the wrong part. Be careful, or ask for help. Also, buy
some spares. My prediction is that your matching monitor will soon
have the same problem.

--
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

==============================================================================
TOPIC: USB malfunction ?
http://groups.google.com/group/sci.electronics.repair/t/ffbb742b61c8b6b2?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, May 5 2010 12:56 am
From: "N_Cook"

that 1K5 will have to go back in , It is the first point of recognition for
USB linking. Next to find why DISCON is permanently H.

==============================================================================
TOPIC: Repairing LCD display on Keithley 580
http://groups.google.com/group/sci.electronics.repair/t/e212b54dc7bbfb3a?hl=en
==============================================================================

== 1 of 2 ==
Date: Wed, May 5 2010 2:41 am
From: JW

Working on a Keithley 580 micro ohm meter that has a display problem. The
first row which controls the bottom segments is very faded - the more
segments that are lit, the more faded they are. I've already used alcohol
to clean the two zebra strips, PCB and LCD itself. I've tried re-orienting
the zebra strips to see if the problem moves; it does not. Checked the
UPD7225 driver chip - pin 17 (COM2) drives this row, it is working fine. I
believe that either the LCD itself is defective, or perhaps the conductor
on the glass is partially open/high resistance. If the latter (and I'm
hoping this is the case) has anyone ever had this sort of problem, and
perhaps tried one of those conductive pens to repair the fault?

Thanks.

== 2 of 2 ==
Date: Wed, May 5 2010 3:46 am
From: "N_Cook"

JW <none@dev.null> wrote in message
news:one2u55tiglr51e0on1ljka77agvneon2r@4ax.com...
> Working on a Keithley 580 micro ohm meter that has a display problem. The
> first row which controls the bottom segments is very faded - the more
> segments that are lit, the more faded they are. I've already used alcohol
> to clean the two zebra strips, PCB and LCD itself. I've tried re-orienting
> the zebra strips to see if the problem moves; it does not. Checked the
> UPD7225 driver chip - pin 17 (COM2) drives this row, it is working fine. I
> believe that either the LCD itself is defective, or perhaps the conductor
> on the glass is partially open/high resistance. If the latter (and I'm
> hoping this is the case) has anyone ever had this sort of problem, and
> perhaps tried one of those conductive pens to repair the fault?
>
> Thanks.

How many backplanes does it use?
ie comparing total number of segments and active pins.
Discover which backplane controls that line , via 50Hz sig gen or similar
and trace a problem on that line

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://diverse.4mg.com/index.htm

==============================================================================
TOPIC: Part # of Magnetron for Microwave Oven Emerson MW9107WC
http://groups.google.com/group/sci.electronics.repair/t/f77addde8cb547fd?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, May 5 2010 4:44 pm
From: Franc Zabkar

On Thu, 29 Apr 2010 09:08:09 -0700 (PDT), Yimin Rong
<yiminrong@yahoo.ca> put finger to keyboard and composed:

>Can someone tell me the part # of the magnetron for microwave oven
>Emerson MW9107WC?

http://www.partstore.com/Part/Funai+Corporation+Inc/Emerson/MW9107W/Funai+Corporation+Inc/Emerson/MW9107WMAG/New.aspx

http://bestbuy.partsearch.com/Part/Funai+Corporation+Inc/Emerson/MW9107W/Funai+Corporation+Inc/Emerson/MW9107WMAG/New.aspx

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

==============================================================================
TOPIC: wholesale gucci shoes, gucci boots, gucci sandals (www.sourcesoso.com)
http://groups.google.com/group/sci.electronics.repair/t/57748167eb7862b0?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, May 5 2010 4:46 pm
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==============================================================================
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http://groups.google.com/group/sci.electronics.repair/t/df7ca7c4603eaab8?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, May 5 2010 7:54 pm
From: ckedsdf

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==============================================================================
TOPIC: Source for replacement rotary encoder?
http://groups.google.com/group/sci.electronics.repair/t/0e0833135f0624c2?hl=en
==============================================================================

== 1 of 7 ==
Date: Wed, May 5 2010 8:36 pm
From: DaveC

<http://i42.tinypic.com/nbt2ci.jpg>
<http://i43.tinypic.com/10rpd3d.jpg>
<http://i39.tinypic.com/28gtmvs.jpg>

How can I find a source for this component (in the US, or anywhere)? It's a
rotary encoder used as an input to a microcontroller to rotate a motor shaft
in small increments in a 10-year old German printing machine.

There are 32 detents per revolution. The unit includes a momentary pushbutton
(when you push on the shaft there is click and tactile feedback).

I presume it's a gray-code quadrature output encoder. Optical? Mechanical?
Only 5 of the pins are used. (Typically power, ground, channel 1, channel 2,
... ?)

Source? Data sheet?

Does this look like Klockner-Moeller? Or it may be Japanese -- the LCD
display for this equipment is Hitachi.

Thanks,
Dave

== 2 of 7 ==
Date: Wed, May 5 2010 9:06 pm
From: "krw@att.bizzzzzzzzzzzz"

On Wed, 5 May 2010 20:36:47 -0700, DaveC <invalid@invalid.net> wrote:

><http://i42.tinypic.com/nbt2ci.jpg>
><http://i43.tinypic.com/10rpd3d.jpg>
><http://i39.tinypic.com/28gtmvs.jpg>
>
>How can I find a source for this component (in the US, or anywhere)? It's a
>rotary encoder used as an input to a microcontroller to rotate a motor shaft
>in small increments in a 10-year old German printing machine.
>
>There are 32 detents per revolution. The unit includes a momentary pushbutton
>(when you push on the shaft there is click and tactile feedback).

We use Bourns optical encoders, like this, for "volume" knobs (double duty for
options scrolling). Grayhill also has some nice products, a little cheaper,
too.

>I presume it's a gray-code quadrature output encoder. Optical? Mechanical?
>Only 5 of the pins are used. (Typically power, ground, channel 1, channel 2,
>... ?)

Ours just have the quadrature output. We use a I2C attached quadrature
counter for control.

>Source? Data sheet?

See above, or try Digikey's online catalog as a starting place.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=1966131&k=optical%20encoder

>Does this look like Klockner-Moeller? Or it may be Japanese -- the LCD
>display for this equipment is Hitachi.

== 3 of 7 ==
Date: Wed, May 5 2010 9:25 pm
From: stratus46@yahoo.com

On May 5, 8:36 pm, DaveC <inva...@invalid.net> wrote:
> <http://i42.tinypic.com/nbt2ci.jpg>
> <http://i43.tinypic.com/10rpd3d.jpg>
> <http://i39.tinypic.com/28gtmvs.jpg>
>
> How can I find a source for this component (in the US, or
anywhere)? It's a
> rotary encoder used as an input to a microcontroller to rotate a
motor shaft
> in small increments in a 10-year old German printing machine.
>
> There are 32 detents per revolution. The unit includes a momentary
pushbutton
> (when you push on the shaft there is click and tactile feedback).
>
> I presume it's a gray-code quadrature output encoder. Optical?
Mechanical?
> Only 5 of the pins are used. (Typically power, ground, channel 1,
channel 2,
> ... ?)
>
> Source? Data sheet?
>
> Does this look like Klockner-Moeller? Or it may be Japanese -- the
LCD
> display for this equipment is Hitachi.
>
> Thanks,
> Dave

http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&WT.z_homepage_link=hp_go_button&KeyWords=gh6102&x=0&y=0

32 detents, incremental quadrature, optical read, tactile switch.

G²

== 4 of 7 ==
Date: Wed, May 5 2010 9:45 pm
From: DaveC

Yes, I can find *a* rotary encoder. I need *this* rotary encoder.

Any idea the make & model of this one? Is EBE the manufacturer?

Thanks,
Dave

== 5 of 7 ==
Date: Wed, May 5 2010 10:16 pm
From: "Royston Vasey"

"DaveC" <invalid@invalid.net> wrote in message
news:0001HW.C807875F02BFBFD4B01AD9AF@news.eternal-september.org...
> <http://i42.tinypic.com/nbt2ci.jpg>
> <http://i43.tinypic.com/10rpd3d.jpg>
> <http://i39.tinypic.com/28gtmvs.jpg>
>
> How can I find a source for this component (in the US, or anywhere)? It's
> a
> rotary encoder used as an input to a microcontroller to rotate a motor
> shaft
> in small increments in a 10-year old German printing machine.
>
> There are 32 detents per revolution. The unit includes a momentary
> pushbutton
> (when you push on the shaft there is click and tactile feedback).
>
> I presume it's a gray-code quadrature output encoder. Optical? Mechanical?
> Only 5 of the pins are used. (Typically power, ground, channel 1, channel
> 2,
> ... ?)
>
> Source? Data sheet?
>
> Does this look like Klockner-Moeller? Or it may be Japanese -- the LCD
> display for this equipment is Hitachi.
>
> Thanks,
> Dave
>

googling should lead you to a source.

A single earch on cesi + encoder gave:

http://img.diytrade.com/cdimg/176657/1202078/0/1144194283.jpg

== 6 of 7 ==
Date: Wed, May 5 2010 10:25 pm
From: "Rich."

It's made by EBE a German company. You might have to try and contact them
through email for the exact replacement part.
http://ebe-gmbh.de/cont/de/ebe/pro/itro/CESI.html

Here's the Google translation of the webpage.
http://translate.google.com/translate?js=y&prev=_t&hl=en&ie=UTF-8&layout=1&eotf=1&u=http%3A%2F%2Febe-gmbh.de%2Fcont%2Fde%2Febe%2Fpro%2Fitro%2FCESI.html&sl=de&tl=en

== 7 of 7 ==
Date: Wed, May 5 2010 10:29 pm
From: dwelz@web.de

DaveC schrieb:
>
> Yes, I can find *a* rotary encoder. I need *this* rotary encoder.
>
> Any idea the make & model of this one? Is EBE the manufacturer?
>

Yes, EBE is the manufacturer, the address is 70771
Leinfelden-Echterdingen Stetten (this is near Stuttgart, the number
being the postal code of Leinfelden-Echterdingen). Their website is
<http://www.ebe-gmbh.de/> and you may try to contact them at
vertrieb@youknowwhat.de, with the obvious replacement.

Martin.

PS: Number of newsgroups cut down to three.

==============================================================================
TOPIC: Task Light just Flickers
http://groups.google.com/group/sci.electronics.repair/t/200662dd1f69bd0a?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, May 5 2010 10:32 pm
From: "don"

I have a Luxo asymmetrical task light which takes an 18 watt bulb, which is
starting to give me trouble. Most of the time it will just flicker as if it
is trying to come on, but sometimes it will flicker once or twice and then
come right on. When it does come on it shines bright. Luxo will not support
this task light anymore because they say it is too old??? even though it
was supposedly guaranteed for life. What is causing this intermittant
problem and how could I fix it? I hate to throw the light out because it
was around $200 when I bought it and it does work fine after it lights up.

==============================================================================
TOPIC: Color changing LEDs
http://groups.google.com/group/sci.electronics.repair/t/0dbbdbcf6a7c8155?hl=en
==============================================================================

== 1 of 3 ==
Date: Wed, May 5 2010 11:20 pm
From: mister_friendly@the-newzgroups.com

I keep seeing these little solar power sidewalk lights. Last year
they were all white (blueish white). Lately I see them where they
change color. Yet, they only have one LED. How can a LED change
color? I thought the color was determined by dopeing it with a metal.
So how can they change? This has me puzzled.

== 2 of 3 ==
Date: Wed, May 5 2010 11:51 pm
From: D Yuniskis

mister_friendly@the-newzgroups.com wrote:
> I keep seeing these little solar power sidewalk lights. Last year
> they were all white (blueish white). Lately I see them where they
> change color. Yet, they only have one LED. How can a LED change
> color? I thought the color was determined by dopeing it with a metal.
> So how can they change? This has me puzzled.

How do you *know* it is "one LED"? I suspect it is a "bicolor"
LED (almost a sure bet if it has more than two leads -- still
possible even with just *two*).

You might want to notice the ranges of colors and consider
what color *mixes* could make them (e.g., red + green LEDs in
the same package will yield yellow-ish -- plus variations from
red *to* green depending on the mixing rates)

== 3 of 3 ==
Date: Thurs, May 6 2010 12:44 am
From: "Phil Allison"

<mister_friendly@the-newzgroups.com>

>I keep seeing these little solar power sidewalk lights. Last year
> they were all white (blueish white). Lately I see them where they
> change color. Yet, they only have one LED. How can a LED change
> color?

** Bi-colour LEDS like this have been around for 30 years.

http://www.effled.com/images/products/bicolor-led/throughhole-led/3mm_Bin_Color_LED_RG.jpg

... Phil

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1 Response to sci.electronics.repair - 18 new messages in 9 topics - digest

ramiz

March 2, 2020 at 2:27 AM

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