sci.electronics.repair - 14 new messages in 10 topics - digest

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==============================================================================
TOPIC: Foregoing warranty rights
http://groups.google.com/group/sci.electronics.repair/t/db33289fb500ca5c?hl=en
==============================================================================

== 1 of 4 ==
Date: Mon, Apr 4 2011 3:14 pm
From: Jeff Liebermann

On Mon, 4 Apr 2011 16:27:32 +0000 (UTC), Meat Plow
<mhywattt@yahoo.com> wrote:

>On Sun, 03 Apr 2011 19:34:29 -0700, Jeff Liebermann wrote:
>
>> On Sun, 03 Apr 2011 20:09:10 -0700, David Nebenzahl
>> <nobody@but.us.chickens> wrote:
>>
>>>So where does that purplish glow come from? I've seen it.
>>
>> Impurities in the glass envelope or gas in the tube.
>>
>> If gas, take an anti-acid tablet and you should be fine in a few
>> minutes.
>>
>> <http://www.vacuumtubes.net/How_Vacuum_Tubes_Work.htm> Scroll down to:
>> C. Blue Glow -- what causes it?
>> for more details.

>So even after a getter flash there is still a certain amount of
>impurities? I've never seen a 6L6 that didn't have some blue inside
>when in operation. It looks as though the blue only occurs where the
>electron beams hit the inside of the glass. At least in new tubes.

Yep. As I vaguely recall (which means I didn't Google for a
reference) glass has the irritating habit of collecting impurities and
volatiles during manufacture. Irving Langmuir figured this out in the
1920's working on light bulbs. He would draw the best vacuum possible
and in a few days, find the bulb full of water vapor and other gasses.
The hot filament would break down the water into hydrogen and oxygen.
The oxygen would then oxidize the electrodes, and blacken the inside
of the bulb.

So, he invented a method of baking the glass to remove the volatiles
prior to evacuation and an acid bath to remove some of the impurities.
It also works nicely for vacuum tubes, but like all such processes, is
far from perfect. There's always some impurities left behind.

When we talk about a "gassy" vacuum tube, it's not a leaky glass
envelope or seal. The getter does best with reactive gases and does
nothing for eliminating noble gases, which will not react with metals
(or most anything else). It's those noble gases that remain (helium,
neon, argon, krypton, xenon, and radon) that you're seeing glow. Most
likely helium and argon mix. The small helium molecule will also
diffuse through the glass from the outside air. See photos at:
<http://en.wikipedia.org/wiki/Noble_gas#Discharge_color>

--
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

== 2 of 4 ==
Date: Mon, Apr 4 2011 4:53 pm
From: "Phil Allison"

"Jeff Liebermann"
>
> When we talk about a "gassy" vacuum tube, it's not a leaky glass
> envelope or seal.

** The term covers that eventuality too.

Any tube that has even a tiny air leak will glow a pinkish purple inside
like a bastard.

> The getter does best with reactive gases and does
> nothing for eliminating noble gases, which will not react with metals
> (or most anything else). It's those noble gases that remain (helium,
> neon, argon, krypton, xenon, and radon) that you're seeing glow.

** Maybe - but how would any significant amount of Argon get inside the
tube UNLESS there was air leaking in ?

Remember, Argon makes up less than 1% of air and does not react with metal
parts.

The vacuum inside a tube is less than one millionth of atmospheric pressure.

BTW:

Nitrogen mixed with a little CO2 makes a nice, white glow under low
pressure - its called a "Moore Tube"

http://en.wikipedia.org/wiki/Daniel_McFarlan_Moore

His untimely death was a bit shocking.

.... Phil

== 3 of 4 ==
Date: Mon, Apr 4 2011 7:27 pm
From: Jeff Liebermann

On Tue, 5 Apr 2011 09:53:16 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

>
>"Jeff Liebermann"
>>
>> When we talk about a "gassy" vacuum tube, it's not a leaky glass
>> envelope or seal.
>
>** The term covers that eventuality too.

Ok. My bad grammar. I meant that if the tube is deemed "gassy", it's
probably not an air leak in the envelope or seal. It's more likely
gaseous diffusion of helium or neon through the envelope.

>Any tube that has even a tiny air leak will glow a pinkish purple inside
>like a bastard.

Yep. I've seen the pink glow. The only way I could tell the
difference between the nitrogen glow of an air leak:
<http://en.wikipedia.org/wiki/Ionized_air_glow>
and that of a helium diffusion through the glass leak:
<http://en.wikipedia.org/wiki/Noble_gas#Discharge_color>
was that the nitrogen glow would not last very long as the filament
would burn out due to oxidation.

>> The getter does best with reactive gases and does
>> nothing for eliminating noble gases, which will not react with metals
>> (or most anything else). It's those noble gases that remain (helium,
>> neon, argon, krypton, xenon, and radon) that you're seeing glow.
>
>** Maybe - but how would any significant amount of Argon get inside the
>tube UNLESS there was air leaking in ?
>
>Remember, Argon makes up less than 1% of air and does not react with metal
>parts.

Oops. Y'er correct. Only helium and neon will diffuse through glass.
Argon and larger gas molecules won't diffuse through glass.

>The vacuum inside a tube is less than one millionth of atmospheric pressure.

Yeah, but the pressure differential is 14.7 lbs/sq-in. Over the
surface of the 6L6, that's about (assuming a cylinder):
Surface Area = 2 Pi r^2 + 2 pi r h
= (2 * 3.14 * 0.7^2) + (2 * 3.14 * 0.7 * 3.0)
= 16 sq-in
Surface pressure = 16 * 14.7 lbs/sq-in = 235 lbs.
(Yes, I'm guessing at the dimension for a 6L6 as I don't have one
handy). That's quite a bit of pressure pushing the helium and neon
atoms through the glass. Still, for helium, the diffusion rate is
slow (helium through pyrex at STP):
<http://teaching.matdl.org/teachingarchives/browser/trunk/matml/transport/problems/hepyrex-solution.pdf?format=raw>
8.0 x 10^-8 m^3/hr

>Nitrogen mixed with a little CO2 makes a nice, white glow under low
>pressure - its called a "Moore Tube"
>http://en.wikipedia.org/wiki/Daniel_McFarlan_Moore
>His untimely death was a bit shocking.

I guess his murderer didn't do a proper patent search before starting
work on his invention. We're more civilized these daze. Instead of
murder, we have litigation. It's much like murder in slow motion.

--
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

== 4 of 4 ==
Date: Mon, Apr 4 2011 8:47 pm
From: "Phil Allison"

"Jeff Liebermann"
"Phil Allison"
>>
>>> When we talk about a "gassy" vacuum tube, it's not a leaky glass
>>> envelope or seal.
>>
>>** The term covers that eventuality too.
>
> Ok. My bad grammar. I meant that if the tube is deemed "gassy", it's
> probably not an air leak in the envelope or seal. It's more likely
> gaseous diffusion of helium or neon through the envelope.

** Unfortunately, that idea is at odds with observations of tubes that show
internal glowing.

Egs: It happens to tubes that are used or not and are old or not PLUS most
even very old tubes show no sign of gas.

The only correlations I have seen are:

1. Certain batches all have the issue.

2. Tubes that have suffered long term overheating.

3. Tubes with visible corrosion on the pins and / or cracks in the glass
near the pins.

..... Phil

==============================================================================
TOPIC: Looking for a TAA621AX1 audio amp chip
http://groups.google.com/group/sci.electronics.repair/t/f7e4c026e133ca72?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Apr 4 2011 4:46 pm
From: David Nebenzahl

On 4/4/2011 3:11 PM Gareth Magennis spake thus:

> "David Nebenzahl" <nobody@but.us.chickens> wrote in message
> news:4d9a3c9e$0$32442$822641b3@news.adtechcomputers.com...
>
>> On 4/4/2011 2:40 PM Bruce Campbell spake thus:
>>
>>> Looking for a TAA621AX1 single channel audio chip. If someone
>>> could point me in the right direction to where I could find one,
>>> that would be great. If anybody has one in his spares box, let me
>>> know! Thanks, P
>>
>> Did you even try a Google search? I did, and came up with this
>> page, which makes it look like it's available from at least 2
>> suppliers:
>>
>> http://octopart.com/taa621ax1-stmicroelectronics-10352435
>>
>> (didn't check further)
>
> Well if you had checked further you would find these are companies that are
> willing to supply devices in industrial quantities only.
>
> I think Bruce is looking for just the one.

Yes, I'm sure you're correct. It's really hard to tell just what pages
such as the one I found are all about, whether they're bona fide or not,
whether intended for large industrial buyers or just onesies-twosies,
etc. Like I said, I didn't check further. It seems that buying
electronic stuff has been made both much easier and infinitely more
difficult since the onset of the Interwebs ...

--
The current state of literacy in our advanced civilization:

yo
wassup
nuttin
wan2 hang
k
where
here
k
l8tr
by

- from Usenet (what's *that*?)

==============================================================================
TOPIC: Extra! Extra! Read all about it! TI to buy Nat'l Semi for $6.5 billion
http://groups.google.com/group/sci.electronics.repair/t/504663494e02158f?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Apr 4 2011 4:47 pm
From: David Nebenzahl

http://money.cnn.com/2011/04/04/technology/texas_instruments_national_semiconductor_deal

--
The current state of literacy in our advanced civilization:

yo
wassup
nuttin
wan2 hang
k
where
here
k
l8tr
by

- from Usenet (what's *that*?)

==============================================================================
TOPIC: How-To: Common Cause Of Flat Panel PS Failure
http://groups.google.com/group/sci.electronics.repair/t/ff5b6703ec041dcc?hl=en
==============================================================================

== 1 of 2 ==
Date: Mon, Apr 4 2011 4:31 pm
From: "Michael A. Terrell"

Bob Villa wrote:
>
> On Apr 1, 6:51 pm, "Michael A. Terrell" <mike.terr...@earthlink.net>
> wrote:
> > Bob Villa wrote:
> >
> > > On Mar 31, 6:20 pm, "Michael A. Terrell" <mike.terr...@earthlink.net>
> > > wrote:
> >
> > > > > Hey Mike when can I expect this PSU to fail...a few years from now?
> > > > > Thanks for your gracious responses.
> >
> > > > When can you post a real question?
> >
> > > Alas, the mastertech doesn't understand sarcasm.
> >
> > You can't even do sarcasm well, and I'm not being sarcastic.
> >
> > --
> > You can't fix stupid. You can't even put a Band-Aid on it, because it's
> > Teflon coated.
>
> The only thing you do well...other than being a critic...is please
> yourself.

Yawn. I built KU band communications equiment that is aboard the
ISS, and all you do is whine.

--
You can't fix stupid. You can't even put a Band-Aid� on it, because it's
Teflon coated.

== 2 of 2 ==
Date: Mon, Apr 4 2011 7:26 pm
From: Bob Villa

On Apr 4, 6:31 pm, "Michael A. Terrell" <mike.terr...@earthlink.net>
wrote:
> Bob Villa wrote:
>
> > On Apr 1, 6:51 pm, "Michael A. Terrell" <mike.terr...@earthlink.net>
> > wrote:
> > > Bob Villa wrote:
>
> > > > On Mar 31, 6:20 pm, "Michael A. Terrell" <mike.terr...@earthlink.net>
> > > > wrote:
>
> > > > > > Hey Mike when can I expect this PSU to fail...a few years from now?
> > > > > > Thanks for your gracious responses.
>
> > > > > When can you post a real question?
>
> > > > Alas, the mastertech doesn't understand sarcasm.
>
> > > You can't even do sarcasm well, and I'm not being sarcastic.
>
> > > --
> > > You can't fix stupid. You can't even put a Band-Aid on it, because it's
> > > Teflon coated.
>
> > The only thing you do well...other than being a critic...is please
> > yourself.
>
> Yawn. I built KU band communications equiment that is aboard the
> ISS, and all you do is whine.
>
> --
> You can't fix stupid. You can't even put a Band-Aid on it, because it's
> Teflon coated.

Holy Crap! I must have cut you deep...now you need to brag. I am so
impressed...especially how you belittle people instead of helping
them.

==============================================================================
TOPIC: NVIDIA GPU defect repair
http://groups.google.com/group/sci.electronics.repair/t/99c97db04cfbb306?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Apr 4 2011 5:06 pm
From: divx dude

On Apr 1, 9:48 pm, Sylvia Else <syl...@not.here.invalid> wrote:
> On 2/04/2011 11:21 AM, divx dude wrote:
>
> > Vostro 1400 DELL laptop withNvidia8400m-gsGPU.
> > i just got into this a couple months ago so am somewhat under informed
> > but have been trying to catch up.
>
> > the lappy arrived to me dead a couple months ago i got to gasp back
> > to life for a few hours and died again.
>
> > reasearched and found defect info and lawsuit claims site. filed and
> > acepted for "free repair" by Dell.
> > skeptical going in seems i was right the got the machine back from
> > Dell , they replaced the "MLB".
> > I immediately ran temperature tool and benchmark 55-60C at idle
> > climbed to 89C after about 20 minutes of benchmark.
>
> Do you really live in a jurisdiction where a company can ship you a dead
> laptop, and not be liable to supply at least a new replacement, if not a
> cash refund?
>
> Consumers are sadly underinformed about their rights in these sorts of
> situation.
>
> Sylvia.

umm ordered in Nov 2007 it died after 13 months in early 2009..
inquired and got deflected with a simple short answer...warranty
expired...
it lay dead in a closet for nearly 2 years until a couple moths ago
when i learned of all this..
apprently Dell gave a year extended warranty over the issue but did
not tell us.

==============================================================================
TOPIC: What causes this kind of failure in a CRT monitor?
http://groups.google.com/group/sci.electronics.repair/t/42b09cf82a8a222c?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Apr 4 2011 6:26 pm
From: "Shaun"

"Slater" <nontelo@dico.no> wrote in message
news:4d99a15c.603015@powernews.libero.it...
> It's doing that thing again. DAMN!!!!

I know what happened.... You plugged tab A into slot D didn't you.

==============================================================================
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http://groups.google.com/group/sci.electronics.repair/t/dbe0813354d4235d?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Apr 4 2011 7:29 pm
From: jialiushoes

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==============================================================================
TOPIC: DTV question [minor]
http://groups.google.com/group/sci.electronics.repair/t/d8b62bf63e76e1c5?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Apr 4 2011 10:18 pm
From: stratus46@yahoo.com

On Apr 4, 3:32 pm, David Nebenzahl <nob...@but.us.chickens> wrote:
> On 4/4/2011 2:29 PM Ian Field spake thus:
>
>
>
>
>
> > "David Nebenzahl" <nob...@but.us.chickens> wrote in message
> >news:4d9a36ed$0$11893$822641b3@news.adtechcomputers.com...
>
> >> On 4/4/2011 2:13 PM Ian Field spake thus:
>
> >>> "David Nebenzahl" <nob...@but.us.chickens> wrote in message
> >>>news:4d9a3211$0$7784$822641b3@news.adtechcomputers.com...
>
> >>>> Does someone here *actually know* how this information is
> >>>> handled, propagated, etc?
>
> >>> Various DVB-T faults get discussed on uk.tech.digital-tv so you
> >>> could try asking there.
>
> >> You use the term "DVB-T" as if that's supposed to mean something to
> >> me. I'd never heard this term before.
>
> >> OK, so it appears to be a *prospective* worldwide DTV
> >> standards-setting body. (Looks suspiciously like yet another
> >> Euro-standard being pushed on us, but never mind.)
>
> >> But is this even applicable to the US? Not sure, even after reading
> >> this, with no mention of DVB-T applying to us:
>
> >>http://www.dvb.org/about_dvb/dvb_worldwide/usa
>
> >> In any case, I'm still looking forward to someone *here* who has at
> >> least an inkling of how textual program information is handled
> >> *here* (the US, where I live).
>
> > You don't seem very grateful for the attempts to help you, so I think I've
> > reached the limit of what I can do for you.
>
> Well, you haven't been very helpful, so I guess we're even.
>
> --
> The current state of literacy in our advanced civilization:
>
> yo
> wassup
> nuttin
> wan2 hang
> k
> where
> here
> k
> l8tr
> by
>
> - from Usenet (what's *that*?)

Go read this as it should help you get started.

http://en.wikipedia.org/wiki/PSIP

G²

==============================================================================
TOPIC: Perfect Universal Abroad Study & Counselling
http://groups.google.com/group/sci.electronics.repair/t/bd71ee84c323542e?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Apr 4 2011 11:29 pm
From: mukinda

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colleges, especially situated in Europe and the right path to join for
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important message about GWC for NGO volunteering networking service
based in Kathmandu, Nepal.

==============================================================================
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: Tues, Apr 5 2011 12:32 am
From: "N_Cook"

Uses "3 disc triple play , play & exchange" 3 drawers stacked over one
another and the CD deck on an elevator system to access them. Can anyone
point to explanation of the mechanics of this or as used in other models.
Uses 6 motors in all. The elevator looks like 2 steppers built inside
cylindrical cam actuators and a mode switch, 5 +5 traces to the motors and
10 way to limit/mode something.

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