Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default 2008 lost LED mons while rained


In Dec 2008 I lost two LED monitors in one week. There was light rain in
both cases but nothing got wet. I mentioned this to other people said this
happened elsewhere. Two insisted it happened to them, and others were
hearsay. The same week!!??

I would appreciate a rational explanation



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Default 2008 lost LED mons while rained

wrote:
In Dec 2008 I lost two LED monitors in one week. There was light rain in both cases but nothing got wet.


If you bought them at the same time and they saw similar use it could be they reached the end of their service life.
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Default 2008 lost LED mons while rained

Jeroni Paul har bragt dette til verden:
wrote:
In Dec 2008 I lost two LED monitors in one week. There was light rain in
both cases but nothing got wet.


If you bought them at the same time and they saw similar use it could be they
reached the end of their service life.


You mean the warranty timer? Set to go off 13 months from purchase :-)

Leif

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Default 2008 lost LED mons while rained

"What's an LED monitor? Is that an LCD monitor with LED backlighting
or did you mean an LCD monitor?"

Yes, that is what the civilians call them. In fact that's what it says on the box usually.

"You mean the warranty timer? Set to go off 13 months from purchase :-) "


That could be alot closer to the truth than most people realize. When you buy the components in very large quantities and they are all exactly the same it makes it almost possible to get it down to a couple of months, semi-reliably. In fact that brings up a topic I am going to start in SED about just that. I'm glad this took that direction which remonded me of it. Collegues in the repair field don't see it but I have pretty good evidence that there is a planned failure of software due to ESR in a certain filter.......

However I do not believe that is the case here. I believe it was luck of the draw actually, even if the actual fault turns out to be the same in each unit. the OP did not specify if they were the exact same model.

Even if the humidity got to ridiculous levels I am still going with luck of the draw because in an LED backlit set there is only a couple hundred volts across each string. In a CCFL backlit set, of a certain model I could go with environmental factors. IIRC there were some Emerson (et alii) models that had problems with part(s) of the backlight array shorting out, which made the inverters look bad. The design was such that you could not disconnect each lamp separately so it wasn't hard to get a bit tripped up. Gawd i am sick of brownwares but after my recent experience with that Tektronix....LOL


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Default 2008 lost LED mons while rained

One was on a Compaq Aero 4/24 I got used. THe aero was the best laptop I
ever used. Ev'tho only DOS, but it was perfect for most things.

THe other a year old siemens monitor. I'm thinking geomagnetic storm because
they both used transformed DC power. Remember it was only drizzling and it
was four days apart.

Now the two 2002 modem incidents made more semce. There was lightning. In
fact in the second case we had a microburst tornado that took off a few roofs
and a fence on my block. I put a surge protector on th eentire phone line
after that.

If one says once burned, twice shy, what do you say for twice burned? I
avoid using any plugged-in computer of my own when it rains as a result.


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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]




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Default 2008 lost LED mons while rained

I would be interested in your findings of evidence that there is a
planned failure of software due to ESR

I am currently reviving LCD Tv's from a recycling company I work for

It is a shame that these tv's are from 2007-2010 and they died
already.

I recently joined a good forum for repairs it is
http://www.badcaps.net/forum/index.php
Bad caps dot net has many people helping other people repair
electronics it helped me a lot

Most of the tv's and monitors I see have blown apart caps and I think
it is not by chance that they pop

Sorry if my message is not in correct newsgroup format
Have been on usenet over 20 years reading but seldom post






On Sun, 4 Aug 2013 13:51:17 -0700 (PDT), wrote:

"What's an LED monitor? Is that an LCD monitor with LED backlighting

or did you mean an LCD monitor?"

Yes, that is what the civilians call them. In fact that's what it says on the box usually.

"You mean the warranty timer? Set to go off 13 months from purchase :-) "


That could be alot closer to the truth than most people realize. When you buy the components in very large quantities and they are all exactly the same it makes it almost possible to get it down to a couple of months, semi-reliably. In fact that brings up a topic I am going to start in SED about just that. I'm glad this took that direction which remonded me of it. Collegues in the repair field don't see it but I have pretty good evidence that there is a planned failure of software due to ESR in a certain filter.......

However I do not believe that is the case here. I believe it was luck of the draw actually, even if the actual fault turns out to be the same in each unit. the OP did not specify if they were the exact same model.

Even if the humidity got to ridiculous levels I am still going with luck of the draw because in an LED backlit set there is only a couple hundred volts across each string. In a CCFL backlit set, of a certain model I could go with environmental factors. IIRC there were some Emerson (et alii) models that had problems with part(s) of the backlight array shorting out, which made the inverters look bad. The design was such that you could not disconnect each lamp separately so it wasn't hard to get a bit tripped up. Gawd i am sick of brownwares but after my recent experience with that Tektronix....LOL


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Default 2008 lost LED mons while rained

"I would be interested in your findings of evidence that there is a

planned failure of software due to ESR "

https://dl.dropboxusercontent.com/u/...6/mitsdpps.jpg

Consider what happens when the ESR of C9015 drops. It looks like it is designed purposely to cause the voltage supply to come out of regulation somewhat at random. You know what happens to certain types of digital circuits when that happens.

I could understand some form of failsafe because as the ESR or C9015 rises the SMPS will tend to put out more voltage to compensate and keep the voltage at C9016 constant because that is where it's sensed. If you repaired Panasonic VCRs in the past you know what can happen, all the other voltages rise, and I fully understand that this is undesirable.

If the real goal was to keep the PS from running too high there are many simpler and more effective ways.

This is obviously not for stability, that's what C9084 and R9014 are for. Note that C9087 is a fairly high value. Playing with the cicuit mentally, like putting a resistor in series with C9015, it looks a bit like an oscillator. Without any DC coupling via the path made by C9087 it would do nothing to actually lower the output of the SMPS, simply make it fluctuate.

The unit that circuit is in is plagued by software problems requiring software "updates" from the manufacturer. The symptoms would vary quite widely for the obvious reason. When I did the software "updates" I changed C9015.

What else would corrupt the data, so CONSISTENTLY, in one certain series of units ? It may have been better software, possibly with better error correction, but that does not explain C9087 and R9088.

Knowing capacitors, what happens ? There is a power outage or the unit gets moved and then it does not work. People might think they broke it in moving and buy another one.
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Default 2008 lost LED mons while rained




What's an LED monitor? Is that an LCD monitor with LED backlighting
or did you mean an LCD monitor?

--
Jeff Liebermann


Yes, what indeed ? When the first 'LED TV' came out a few years back, I had
a heated thread going on on here about it, in which I claimed that they were
misleading the public because the display technology was not LED as was
being implied, but instead was plain old LCD, being backlit by LEDs. I can't
remember who the manufacturer was - Sharp maybe ? - but anyway, after a few
months of selling and advertising it in this way, the wording was subtly
changed to reflect the fact that it was just an LCD panel. Perhaps one of
their engineers reads S.E.R. :-)

Arfa


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Default 2008 lost LED mons while rained

"Arfa Daily" wrote in message
...



What's an LED monitor? Is that an LCD monitor with LED backlighting
or did you mean an LCD monitor?

--
Jeff Liebermann


Yes, what indeed ? When the first 'LED TV' came out a few years back, I
had a heated thread going on on here about it, in which I claimed that
they were misleading the public because the display technology was not LED
as was being implied, but instead was plain old LCD, being backlit by
LEDs. I can't remember who the manufacturer was - Sharp maybe ? - but
anyway, after a few months of selling and advertising it in this way, the
wording was subtly changed to reflect the fact that it was just an LCD
panel. Perhaps one of their engineers reads S.E.R. :-)

Arfa



Ah, but edge-lit LED displays are some crazy-ass technology! The way light
propagates through those things is amazing!

Mark Z.



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Default 2008 lost LED mons while rained

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