sci.electronics.repair@googlegroups.com

Today's topics:

* Blew another damn transformer on my Trane XB80 - 4 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/f883cd09a3a0b791?hl=en
* LG refrigerator model LBN2251#** problems - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/a8a81578d072145d?hl=en
* PAYPAL WHOLESALE all BRAND(UGG BOOTS,SHOES,CLOTHES,HANDBAG,WATCH,JEANS,
JERSEY,T-SHIRT,SHIRTS,HOODY,EYEGLASS,CAP,SHAWL,WALLT) and so on http://www.24
hours-online.com/. - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/8cb7e30537b683c3?hl=en
* Rigol scope LCD problem - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/f09ee6418c07d961?hl=en
* JVC MXD 752 CD etc compact audio unit - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/8b7f65038283bf79?hl=en

==============================================================================
TOPIC: Blew another damn transformer on my Trane XB80
http://groups.google.com/group/sci.electronics.repair/t/f883cd09a3a0b791?hl=en
==============================================================================

== 1 of 4 ==
Date: Sun, Apr 10 2011 8:27 pm
From: Jeff Thies

On 4/10/2011 10:46 PM, Phil Allison wrote:
> "Jeff Thies"
> Phil Allison wrote:
>
>>>>> I suggest you provide the next replacement for that vulnerable tranny
>>>>> with
>>>>> some "protection" - firstly an in-line fuse of say 1/4 amp AND a
>>>>> capacitor wired across the primary of say 1uF rated for continuous use
>>>>> across the AC supply.
>>>>>
>>>>> If there is an overload on the tranny, the fuse will blow.
>>>>>
>>>>> The 1uF capacitor should suppress spike voltages enough to save the
>>>>> tranny from harm.
>>>>
>>>> 1 uF sounds a little high.
>>>
>>>
>>> ** No it ain't.
>>
>> I thought you had simply misspoke and that this was an honest error.
>>
>> The reactance of a 1uF cap at 60Hz is: 2652 ohms (1/(2*pi*F*C)
>> Online calculator:
>> http://www.kusashi.com/reactance-c.php?f=60&c=1&stage=results
>>
>> V^2/R = W
>>
>> Assuming primary, as why would you put it on the secondary:
>>
>> 120^2 / 2652 = 5.43 W
>>
>> Does that not seem wrong to you?
>
> ** Completely.
>
> Such a cap dissipates no energy at all.
>
> What planet do you come from ??

What a jerk you are. You do realize that is 45mA running through that.

Jeff

== 2 of 4 ==
Date: Sun, Apr 10 2011 8:29 pm
From: "Phil Allison"

"Jeff Thies"
> Phil Allison wrote:
>> "Jeff Thies"
>> Phil Allison wrote:
>>
>>>>>> I suggest you provide the next replacement for that vulnerable tranny
>>>>>> with
>>>>>> some "protection" - firstly an in-line fuse of say 1/4 amp AND a
>>>>>> capacitor wired across the primary of say 1uF rated for continuous
>>>>>> use
>>>>>> across the AC supply.
>>>>>>
>>>>>> If there is an overload on the tranny, the fuse will blow.
>>>>>>
>>>>>> The 1uF capacitor should suppress spike voltages enough to save the
>>>>>> tranny from harm.
>>>>>
>>>>> 1 uF sounds a little high.
>>>>
>>>>
>>>> ** No it ain't.
>>>
>>> I thought you had simply misspoke and that this was an honest error.
>>>
>>> The reactance of a 1uF cap at 60Hz is: 2652 ohms (1/(2*pi*F*C)
>>> Online calculator:
>>> http://www.kusashi.com/reactance-c.php?f=60&c=1&stage=results
>>>
>>> V^2/R = W
>>>
>>> Assuming primary, as why would you put it on the secondary:
>>>
>>> 120^2 / 2652 = 5.43 W
>>>
>>> Does that not seem wrong to you?
>>
>> ** Completely.
>>
>> Such a cap dissipates no energy at all.
>>
>> What planet do you come from ??
>
> What a jerk you are. You do realize that is 45mA running through that.

** What sort of know nothing JERK thinks that capacitors dissipate energy
??

Then proceeds to calculate the reactive impedance and treat it the same as
resistance ??

Big bad.

Zero out of ten.

.... Phil

== 3 of 4 ==
Date: Sun, Apr 10 2011 10:33 pm
From: clare@snyder.on.ca

On Mon, 11 Apr 2011 13:25:02 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

>
><clare@snyder.on.ca>
> "Phil Allison"
>>
>>
>>>High voltage spikes on the primary could also cause insulation failure
>>>leading to the damage seen in the pics - lightning does this sort of
>>>thing.
>>>So also could back emfs from the blower fan if the is a bad connection in
>>>the AC supply feed.
>>
>>>I suggest you provide the next replacement for that vulnerable tranny with
>>>some "protection" - firstly an in-line fuse of say 1/4 amp AND a
>>>capacitor wired across the primary of say 1uF rated for continuous use
>>>across the AC supply.
>>>
>>>If there is an overload on the tranny, the fuse will blow.
>>>
>>>The 1uF capacitor should suppress spike voltages enough to save the tranny
>>>from harm.
>>>
>>>
>>
>> A capacitor across an AC supply??????????????? As a surge
>> protector????
>> Have not heard of that before.
>
>
>** Then your ignorance is showing.
>
> The stated reason for the capacitor was in relation to the "blower fan"
>inside the same unit as the small tranny.
>
> The event the cap has to deal with is a back emf surge generated by that
>fan when the AC supply is suddenly disconnected - for whatever reason.
>
>
>> A capacitor across the AC line would appear as a load
>
>** Draws 45mA continuously.
>
> Yawnnnnnnn....
>
>> - and could form a resonant l/ci tank circuit,
>
>** Yawnnnnnn....
>
> (snip absurd drivel)
>
>
>> There are 2 other POSSIBLE issues here though - - -.
>>
>> Both are perhaps long shots - but mabee worth investigating.
>>
>> The transformer primary APPEARS to be saturating.
>
>
>** The primary appears to be EXPLODING !!
>
> You ridiculous wanker.
>
>
>.... Phil
>
Phil - your mamma should wash your mouth out with soap.
I SAID the other two scenarios were long shots - but so is everything
else that has been suggested. The windings of the trasnformer do not
APPEAR to be overheated - looks like just blackened at the connections
between the winding and the connecting wires.

It is definitely a strange failure - and I don't think it has been
properly analyzed to determine exactly what/where the problem is.
As Arthur Conan Doyle said, "after you have eliminated all the
possibilities, whatever remains, however improbable, must be the
truth"

== 4 of 4 ==
Date: Sun, Apr 10 2011 10:48 pm
From: "Phil Allison"

<clare@snyder.on.ca>

>>** The primary appears to be EXPLODING !!
>>
>> You ridiculous wanker.
>>
> Phil - your mamma should wash your mouth out with soap.

** You need to get your hands off of it.

> I SAID the other two scenarios were long shots ..

** And I said they were ridiculous drivel.

> - but so is everything else that has been suggested.

** Your opinion is based on your ignorance only.

> The windings of the trasnformer do not
> APPEAR to be overheated - looks like just blackened at the connections
> between the winding and the connecting wires.

** See the vaporised metal coating deposited on the plastic cover next to
the tranny?

That is a damn EXPLOSION !!

It happened very suddenly and made a loud bang too.

I said:

" High voltage spikes on the primary could also cause insulation failure
leading to the damage seen in the pics - lightning does this sort of thing.
So also could back emfs from the blower fan if the is a bad connection in
the AC supply feed."

If the insulation on the enamel wire of the primary is punctured by a HIGH
VOLTAGE SPIKE, effectively shorting out most of the primary - then the
120 AC supply ( no fuse exists remember ) will easily turn the two exposed
wire ends into metal vapour !!!

Cos they just became the fuses.

It just so happens that many small transformers made in China, India & Sri
Lanka etc are very prone to this sort of failure - due to bad manufacturing
practices.

.... Phil

==============================================================================
TOPIC: LG refrigerator model LBN2251#** problems
http://groups.google.com/group/sci.electronics.repair/t/a8a81578d072145d?hl=en
==============================================================================

== 1 of 2 ==
Date: Sun, Apr 10 2011 9:38 pm
From: Fred McKenzie

In article
<prestwhich-6ED069.19501710042011@mx01.eternal-september.org>,
Smitty Two <prestwhich@earthlink.net> wrote:

> Lots of troubleshooting guides on the net, but the easiest thing to try
> first is a 24 hour defrost.

Klem-

If the 24 hour defrost appears to clear your problem, you may find it
was caused by failure of the automatic defrost.

I had a Frigidaire refrigerator with a defrost timer whose motor stopped
in defrost mode. If yours works like mine, its motor may have stopped
in refrigeration mode, causing a buildup of frost.

My defrost timer was available at a local appliance parts dealer, and
was easy to change.

Fred

== 2 of 2 ==
Date: Sun, Apr 10 2011 10:08 pm
From: Geoff

klem kedidelhopper <captainvideo462009@gmail.com> wrote in news:dd664d3b-
3c48-492b-b116-20f9a8e7ef64@v10g2000yqn.googlegroups.com:

> The refrigerator section is running at about 46 degrees and the
> freezer is at 42. We cleaned all the dust out of the back and there
> doesn't seem to be any improvement. I am an electronics technician
> however I don't know too much about refrigerators. All the food is
> spoiling and I' hope that someone can please point me in the right
> direction to troubleshoot this thing. We had a GE for 22 years and
> against my better judgment had to get rid of it because my wife didn't
> like the rust on the bottom. Now we're stuck with this non functioning
> pos. Thanks for any assistance. Lenny
>

Could be failure of defrost system, even if compressor is running. You can
check by removing the cover in the back of the freezer section, if that is
how you get to the freezer coill thingies, the aluminium bits.

This causes the ice that is there to slow the flow of air from the fans to
the fridge compartments. Next step is to find out why, if this is
happening.

==============================================================================
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hours-online.com/.
http://groups.google.com/group/sci.electronics.repair/t/8cb7e30537b683c3?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Apr 10 2011 11:36 pm
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==============================================================================
TOPIC: Rigol scope LCD problem
http://groups.google.com/group/sci.electronics.repair/t/f09ee6418c07d961?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Apr 11 2011 12:41 am
From: "N_Cook"

<a7yvm109gf5d1@netzero.com> wrote in message
news:9e7527b4-b0af-4d2b-974a-cd7794accb9a@y26g2000yqd.googlegroups.com...
> DS5102C, color LCD scope. When turned on, the leftmost quarter has
> vertical stripes, the affected column is dead.
>
> It looks like specific sub-pixels are not responding. R in one row is
> dead, then G a few rows down, then B, repeat 10 times.
>
> http://img593.imageshack.us/i/rigollcdscreen.jpg/
>
> Thing is, after a few hour warm up, it works normally.
>
> What is the most likely suspect before I go in and strip it down? Is
> it likely to be simply a bad harness somewhere that needs reseating?
> Or do I need to take apart the panel and fiddle arround with something
> more arcane?
>
> I don't think there's zebra strips in these things these days.

I would get inside and lightly probe with fingers, either final bond to the
LCD failed somewhere or solder problem on a demultiplexer chip. If bond
failure , do not try debonding and rebonding . That plastic reticulated
foam, pan scourer, pressed against the suspect area and padded/braced
against something is about all you can expect to remedy, unlikely to be
zebra strip.

==============================================================================
TOPIC: JVC MXD 752 CD etc compact audio unit
http://groups.google.com/group/sci.electronics.repair/t/8b7f65038283bf79?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Apr 11 2011 12:45 am
From: "N_Cook"

could not find cause of intermittant lock-up of tray, so cut a neat hole in
the outer metal casing over the tray lock tabs that protrude outwards of the
deck section, perfectly safe area. Grommet strip edged around. Owner then
can manually unlock the tray and pull out the tray himself.

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