I am in Hawaii where power surges are unfortunately common. Having lost
several PC power supplies, I now use line conditioning battery backup units
to protect my PCs.
Several months ago I salvaged a Westington flat screen [LTV-32w6 HD] that
had been abandoned because the tuner failed. As the tuner is part of the
motherboard I didn't fix it was easier to use an external VCR as the tuner.
TV functions fine. I assume the tuner died in a power surge.
Yesterday, the power failed and I awoke to find that the TV had turned
itself on but no sound. Toggling mute and adding external speakers did not
work. I assumed the worst but guessed that maybe this was a microprocessor
locked into mute. I unplugged the set and tried again after 15 minutes.
Sound was restored. Whew!
I wonder how many consumers would be so lucky? Is this type of sensitivity
common? [I have a nice old 32inch CRT that has been immmune from these
problems and provides a great picture.] I'll probably add a line
conditioner, but, really, are consumers expected to be that cautious?

Yesterday, the power failed and I awoke to find that the TV
had turned itself on but no sound. Toggling mute and adding
external speakers did not work. I assumed the worst but
guessed that maybe this was a microprocessor locked into
mute. I unplugged the set and tried again after 15 minutes.
Sound was restored. Whew!

I've experienced this sort of failure with several items -- including an LV
player, a TV set, a PDA, and a DVD player -- over the past 25 years. I call
it "CMOS lockup", though whether that's the actual cause of the problem, I
don't know.

Basically, the product "misbehaves" in some way -- including apparent
"death". Removing the batteries or unplugging it, and then letting it sit
for a while, causes it to be "recalled to life" (Dickens). Sometimes you
need to yank the power cord while the device is running.

I don't know the exact cause, but I suspect it happens often enough that
people discard products that are otherwise perfectly good.

On Fri, 10 Dec 2010 07:11:18 -1000, "John Keiser"
wrote:

I am in Hawaii where power surges are unfortunately common. Having lost
several PC power supplies, I now use line conditioning battery backup units
to protect my PCs.
Several months ago I salvaged a Westington flat screen [LTV-32w6 HD] that
had been abandoned because the tuner failed. As the tuner is part of the
motherboard I didn't fix it was easier to use an external VCR as the tuner.
TV functions fine. I assume the tuner died in a power surge.
Yesterday, the power failed and I awoke to find that the TV had turned
itself on but no sound. Toggling mute and adding external speakers did not
work. I assumed the worst but guessed that maybe this was a microprocessor
locked into mute. I unplugged the set and tried again after 15 minutes.
Sound was restored. Whew!
I wonder how many consumers would be so lucky? Is this type of sensitivity
common? [I have a nice old 32inch CRT that has been immmune from these
problems and provides a great picture.] I'll probably add a line
conditioner, but, really, are consumers expected to be that cautious?

There are big differences between the 32" CRT and the 32 inch flat
panel. First, the CRT is the product of more than 50 years of
refinement. Comparitively speaking the flat screen is in it's
infancy.

Second, the CRT set is almost certainly primarily analog. The flat
screen has several processors, and is much more susceptible to
interference.

Third, most flat panel sets are put together out of crappy components,
especially the capacitors. While the power supply might have been
adequate when new, the caps have deteriorated and are allowing noise
from the SMPS onto the power supply rails.

PlainBill

Third, most flat panel sets are put together out of crappy components,
especially the capacitors.

Dell is hoping there are no more of those crappy-caps around!

On Fri, 10 Dec 2010 12:11:00 -0800 (PST), Bob Villa
wrote:

Third, most flat panel sets are put together out of crappy components,
especially the capacitors.

Dell is hoping there are no more of those crappy-caps around!

Dell was not using "crappy" capacitors. What they were doing is the
same thing that almost every other manufactory is currently also
doing. They are rating their electrolytics as close to the bitter
edge of failure as possible. That saves a few pennies in cost by
using a lower voltage electrolytic but shortens the capacitor life. My
guess(tm) is that Dell's OEM supplier in China selected the capacitors
based upon faulty calculations, where it was designed to blow up in
about 5 years, instead of the 1-2 years specified in the class action
suit.

"Determining end-of-life, ESR, and lifetime calculations for
electrolytic capacitors at higher temperatures"
http://www.dfrsolutions.com/uploads/white-papers/Uprating_of_Electrolytic_Capacitors.pdf
At the bottom of the paper, note the various ways in which the ESR can
climb as a result varying conditions. At 105C (rated max temp), a
typical capacitor will have its ESR increase 5 times (and therefore 5
times the dissipation) after 3500 hrs of normal operation. For
24hr/day operation, that's only about 5 months of continuous
operation.

This has nothing to do with the original question, but I thought it
might be interesting.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

Jeff Liebermann wrote:

On Fri, 10 Dec 2010 12:11:00 -0800 (PST), Bob Villa
wrote:

Third, most flat panel sets are put together out of crappy components,
especially the capacitors.

Dell is hoping there are no more of those crappy-caps around!

Dell was not using "crappy" capacitors. What they were doing is the
same thing that almost every other manufactory is currently also
doing. They are rating their electrolytics as close to the bitter
edge of failure as possible. That saves a few pennies in cost by
using a lower voltage electrolytic but shortens the capacitor life. My
guess(tm) is that Dell's OEM supplier in China selected the capacitors
based upon faulty calculations, where it was designed to blow up in
about 5 years, instead of the 1-2 years specified in the class action
suit.

I don't know about Dell LCDs, but their computer motherboards of 5-8
years ago that failed at high rates were actually made with very good
brands of capacitors, like Rubycon, Nichicon, and Panasonic, not the
common crap found on many other motherboards . Unfortunately Nichicon
produced bad batches of their HM and HN series caps, marked HM(M) and
HN(M), from around 2001-2004.

On Mon, 13 Dec 2010 18:02:46 -0800 (PST), "larry moe 'n curly"
wrote:



Jeff Liebermann wrote:

On Fri, 10 Dec 2010 12:11:00 -0800 (PST), Bob Villa
wrote:

Third, most flat panel sets are put together out of crappy components,
especially the capacitors.

Dell is hoping there are no more of those crappy-caps around!

Dell was not using "crappy" capacitors. What they were doing is the
same thing that almost every other manufactory is currently also
doing. They are rating their electrolytics as close to the bitter
edge of failure as possible. That saves a few pennies in cost by
using a lower voltage electrolytic but shortens the capacitor life. My
guess(tm) is that Dell's OEM supplier in China selected the capacitors
based upon faulty calculations, where it was designed to blow up in
about 5 years, instead of the 1-2 years specified in the class action
suit.

I don't know about Dell LCDs, but their computer motherboards of 5-8
years ago that failed at high rates were actually made with very good
brands of capacitors, like Rubycon, Nichicon, and Panasonic, not the
common crap found on many other motherboards . Unfortunately Nichicon
produced bad batches of their HM and HN series caps, marked HM(M) and
HN(M), from around 2001-2004.

Just finished working on a Dell Optiplex that has 8 Rubyicon 1800 uf
6,3v caps in a row; all of which were leaking out the top of the caps.
The failure rate of Rubycon capacitors was high back when I was
repairing televisions, particularly Mitsubishis of the late 90s.
Chuck

On Mon, 13 Dec 2010 18:02:46 -0800 (PST), "larry moe 'n curly"
wrote:

Jeff Liebermann wrote:

On Fri, 10 Dec 2010 12:11:00 -0800 (PST), Bob Villa
wrote:

Third, most flat panel sets are put together out of crappy components,
especially the capacitors.

Dell is hoping there are no more of those crappy-caps around!

Dell was not using "crappy" capacitors. What they were doing is the
same thing that almost every other manufactory is currently also
doing. They are rating their electrolytics as close to the bitter
edge of failure as possible. That saves a few pennies in cost by
using a lower voltage electrolytic but shortens the capacitor life. My
guess(tm) is that Dell's OEM supplier in China selected the capacitors
based upon faulty calculations, where it was designed to blow up in
about 5 years, instead of the 1-2 years specified in the class action
suit.

I don't know about Dell LCDs, but their computer motherboards of 5-8
years ago that failed at high rates were actually made with very good
brands of capacitors, like Rubycon, Nichicon, and Panasonic, not the
common crap found on many other motherboards . Unfortunately Nichicon
produced bad batches of their HM and HN series caps, marked HM(M) and
HN(M), from around 2001-2004.

I think you just demonstrated my point. It's not the brand or even
the quality of the caps. It's the voltage rating. In most cases, the
capacitors voltage rating is just too close to the operating voltage.
Filtering a 5vDC power supply line with 6.3v caps is just asking for
the caps to blow up. I've ranted on the subject before but am a bit
busy to dig out references right now. Short summary is that
electrolytics will derate substantially under high temperatures. The
ESR will also climb, causing increased self heating. Drops in
capacitance will cause increased ripple, which will produce increased
ripple current, which will result in additional heating. Manufacturers
can search forever to find a better quality 6.3v capacitor, but what's
really needed is to spend a few pennies more and use a 10v capacitor.

Electrolytic life calculators:
http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx
http://www.cde.com/calc/
http://www.niccomp.com/Products/General/Alumlyticlifeexpect.pdf
http://powerelectronics.com/images/archive/ElectrolyticCap.pdf


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Hi John,

John Keiser wrote:
Several months ago I salvaged a Westington flat screen [LTV-32w6 HD] that
had been abandoned because the tuner failed. As the tuner is part of the
motherboard I didn't fix it was easier to use an external VCR as the tuner.
TV functions fine. I assume the tuner died in a power surge.
Yesterday, the power failed and I awoke to find that the TV had turned
itself on but no sound. Toggling mute and adding external speakers did not
work. I assumed the worst but guessed that maybe this was a microprocessor
locked into mute. I unplugged the set and tried again after 15 minutes.
Sound was restored. Whew!
I wonder how many consumers would be so lucky? Is this type of sensitivity
common? [I have a nice old 32inch CRT that has been immmune from these
problems and provides a great picture.] I'll probably add a line
conditioner, but, really, are consumers expected to be that cautious?

Most modern devices use mmicroprocessors or microcontrollers. Often
*several* (VCRs typically had three or four; my cassette deck has
one just to count capstan revolutions!).

If power fails -- wholly or partially -- it is possible for any
of those processors to reset. Or, *partially* reset. Or, "get
confused" (and head off to never-never land doing something
unintended -- like "executing" *data*).

If the processor doesn't have brownout detection (or it isn;t
implemented properly), a processor can get stuck in one of these
confused states. If the processor doesn't have a hardware
watchdog (or, it isn;t implemented properly), once confused it
can fail to get OUT of that state.

Regardless, sloppy code in one or more of these can result
in them running, but failing to move to their *correct*
operational state. This is a common sort of bug -- the
code makes assumptions (implicitly or explicitly) that,
suddenly, are not valid (because something unforseen has
happened -- e.g., a power glitch between instructions
102,678,993 and 102,678,994). Because the programmer made
those assumptions, he didn't code to protect *against*
them being incorrect.

So, for example, if there are two processors in the set,
they *always* are powered up at the same exact instant
(there is ONLY one power button, right?). And, the code
that they execute never changes. So, 23.0257 milliseconds
after RESET, processor #1 has done blah and can now
send the "OK, I am ready to fire up the display" message
to processor #2. Meanwhile, 24.6802 milliseconds after
RESET, processor #2 goes looking for the "OK I am ready"
message, *sees* it (since it was delivered about a millisecond
earlier) and correctly fires up the display.

Now, if something happens that causes processor #1 to come
out of RESET a bit later -- perhaps, 3 milliseconds (e.g.,
maybe power at *it's* reset circuit glitched a bit more than
at #2's; or, it's brownout detector fired *twice* instead of
once) -- then it (#1) might not issue the "OK" message until
26.0257 milliseconds (since it's RESET was 3 milliseconds
later than #2's). Meanwhile, at 24.6802 milliseconds, processor
#2 went looking for the message AND IT WASN'T THERE!!

Had the programmer NOT *assumed* the message *would* be there,
he would have told #2 to wait for it -- for some amount of time.
Instead, he might just crash; or, *incorrectly* (buggy) "wait";
or, fire up the display prematurely causing some other fault
(that shuts him down -- or, something *else* gets shut down), etc.

The heat of almost ALL software bugs is one or more bad assumptions.
When the world behaves in ways programmers don't expect, you
get "anomalous behaviors" -- things that seeem unexplained and
that change without any action on your part to "fix" them.

shrug Makes you wonder how *anything* works properly! :-/

(of course, there can also be hardware issues that are causing
this -- like a cap not completely discharging so the circuit
it connects to never sees the "reset")

Thanks for the details.
Doesn't instill consumer confidence in buying new expensive electronics!



"D Yuniskis" wrote in message
...
Hi John,

John Keiser wrote:
Several months ago I salvaged a Westington flat screen [LTV-32w6 HD] that
had been abandoned because the tuner failed. As the tuner is part of the
motherboard I didn't fix it was easier to use an external VCR as the
tuner. TV functions fine. I assume the tuner died in a power surge.
Yesterday, the power failed and I awoke to find that the TV had turned
itself on but no sound. Toggling mute and adding external speakers did
not work. I assumed the worst but guessed that maybe this was a
microprocessor locked into mute. I unplugged the set and tried again
after 15 minutes. Sound was restored. Whew!
I wonder how many consumers would be so lucky? Is this type of
sensitivity common? [I have a nice old 32inch CRT that has been immmune
from these problems and provides a great picture.] I'll probably add a
line conditioner, but, really, are consumers expected to be that
cautious?

Most modern devices use mmicroprocessors or microcontrollers. Often
*several* (VCRs typically had three or four; my cassette deck has
one just to count capstan revolutions!).

If power fails -- wholly or partially -- it is possible for any
of those processors to reset. Or, *partially* reset. Or, "get
confused" (and head off to never-never land doing something
unintended -- like "executing" *data*).

If the processor doesn't have brownout detection (or it isn;t
implemented properly), a processor can get stuck in one of these
confused states. If the processor doesn't have a hardware
watchdog (or, it isn;t implemented properly), once confused it
can fail to get OUT of that state.

Regardless, sloppy code in one or more of these can result
in them running, but failing to move to their *correct*
operational state. This is a common sort of bug -- the
code makes assumptions (implicitly or explicitly) that,
suddenly, are not valid (because something unforseen has
happened -- e.g., a power glitch between instructions
102,678,993 and 102,678,994). Because the programmer made
those assumptions, he didn't code to protect *against*
them being incorrect.

So, for example, if there are two processors in the set,
they *always* are powered up at the same exact instant
(there is ONLY one power button, right?). And, the code
that they execute never changes. So, 23.0257 milliseconds
after RESET, processor #1 has done blah and can now
send the "OK, I am ready to fire up the display" message
to processor #2. Meanwhile, 24.6802 milliseconds after
RESET, processor #2 goes looking for the "OK I am ready"
message, *sees* it (since it was delivered about a millisecond
earlier) and correctly fires up the display.

Now, if something happens that causes processor #1 to come
out of RESET a bit later -- perhaps, 3 milliseconds (e.g.,
maybe power at *it's* reset circuit glitched a bit more than
at #2's; or, it's brownout detector fired *twice* instead of
once) -- then it (#1) might not issue the "OK" message until
26.0257 milliseconds (since it's RESET was 3 milliseconds
later than #2's). Meanwhile, at 24.6802 milliseconds, processor
#2 went looking for the message AND IT WASN'T THERE!!

Had the programmer NOT *assumed* the message *would* be there,
he would have told #2 to wait for it -- for some amount of time.
Instead, he might just crash; or, *incorrectly* (buggy) "wait";
or, fire up the display prematurely causing some other fault
(that shuts him down -- or, something *else* gets shut down), etc.

The heat of almost ALL software bugs is one or more bad assumptions.
When the world behaves in ways programmers don't expect, you
get "anomalous behaviors" -- things that seeem unexplained and
that change without any action on your part to "fix" them.

shrug Makes you wonder how *anything* works properly! :-/

(of course, there can also be hardware issues that are causing
this -- like a cap not completely discharging so the circuit
it connects to never sees the "reset")

Hi John,

John Keiser wrote:
Thanks for the details.
Doesn't instill consumer confidence in buying new expensive electronics!

I'm not claiming that this is what you *actually* experienced.
But, it is the sort of thing that is commonplace -- increasingly
so, nowadays.

E.g., I have a pair of Nakamichi Dragons (high end cassette decks,
now very "dated"). They are "autoreverse" decks -- when the
tape reaches the end of side A, side B is played (i.e., AS IF
the tape had been "flipped" -- though this is done without
any mechanical motion).

The tape counter, on reaching the end of side A, should start
counting *backwards* as it begins playing side B (i.e., the
counter should end up wherever it originally started once
side B is complete -- assuming you started at the beginning of
side A).

This is, in fact, how it works. There are two "play" buttons
on the deck -- "play forward" (side A) and "play backwards"
(side B). While play forward is active, you will see the
counter increasing. If you press "play backwards", the
counter will *decrease*.

*BUT*... if you stop the tape just as it reaches the end of side
A, open the tape door, remove the tape, flip it over (so, now
side B is "in front"), close the door and press "play forward",
the tape will COUNT BACKWARDS (i.e., as if the tape was still
installed in the deck playing "side B" BACKWARDS). So, the
tape MOVES "forwards" (the machine has no way of knowing that
this is "side 2" of the tape... it may be a completely DIFFERENT
tape!) while the counter counts BACKWARDS!

If you had stopped the tape a second BEFORE it reached the end
of side A, ejected it, flipped it, reinstalled it and pressed
"play forward", the counter would NOT count backwards.

I.e., this is a bug. (technically, a "race") Would you
expect that sort of thing in a $2K device? On something
so *trivial*?? :

Makes you wonder next time you get on an aircraft ("fly by wire"),
have a surgical procedure ("Doctor, the patient's blood pressure
is 9843 over 2"), etc. :-/

Maybe the Luddites were onto something, afterall! :

Makes you wonder next time you get on an aircraft ("fly by wire"),
have a surgical procedure ("Doctor, the patient's blood pressure
is 9843 over 2"), etc. :-/

Maybe the Luddites were onto something, afterall! :

Yes, exactly. Coders are very bright (theoretically speaking) folks, but
they cannot see the future. Unanticipated, although normal, events and
other random glitches/failures can conspire to send controllers/chips into
endless loops or into a routine that is entirely inappropriate. We have
engineered ourselves into an untenable position. Anyway, for now, just shut
everything down and turn the devices back on using a recommended sequence
(good luck with that).

Hi Charles,

Charles wrote:
Makes you wonder next time you get on an aircraft ("fly by wire"),
have a surgical procedure ("Doctor, the patient's blood pressure
is 9843 over 2"), etc. :-/

Maybe the Luddites were onto something, afterall! :

Yes, exactly. Coders are very bright (theoretically speaking) folks,

frown You are more "generous" than I! :

but they cannot see the future. Unanticipated, although normal, events
and other random glitches/failures can conspire to send
controllers/chips into endless loops or into a routine that is entirely

But, you needn't "see the future" to code against these things!
All you have to do is step back (figuratively) and look at
your design and ask yourself: "What have I taken for granted,
here?" Then, go back and "UN"-take it for granted.

Of course, there are some things that you *have* to "assume".
But, far less than you actually usually *do* assume (at least
if you want a robust design!).

E.g., if you loan someone money, do you *assume* you will be
paid back AND HAVE NO CONTINGENCY PLANS FOR THE POSSIBILITY
OF *not* BEING PAID BACK? (if so, I'd like to speak to you
about a loan... : )

inappropriate. We have engineered ourselves into an untenable
position. Anyway, for now, just shut everything down and turn the
devices back on using a recommended sequence (good luck with that).

"John Keiser" wrote in message
news:FYWdnYqJUrg7Cp_QnZ2dnUVZ_i2dnZ2d@powerusenet. com...

Thanks for the details.
Doesn't instill consumer confidence in buying new expensive electronics!

D Yuniskis did a nice job but only touched on a few things that can go
wrong. In any case, my thanks to him for taking the time to explain the
issues.

Consumers are becoming more clueless as software takes over their lives.
This is a problem that is becoming more serious. If the doctors and nurses
and technicians in a modern operating room get confused or misled by
software glitches, it could be really, really serious. Has already
happened.

Hi Charles,

Charles wrote:
Consumers are becoming more clueless as software takes over their lives.

The problem is that consumers don't *want* to know how things
work or *should* work. And, they don't "vote with their wallet".
They get a crappy product and they either live with it (possibly
not even knowing how crappy it is!) or toss it out and buy another
(probably EQUALLY as crappy)

This is a problem that is becoming more serious. If the doctors and
nurses and technicians in a modern operating room get confused or misled
by software glitches, it could be really, really serious. Has already
happened.

Google "Therac".

Unfortunately, there are no real safeguards in place to *prevent*
this sort of thing happening. There are "practices" that *should*
minimize the chance of it happening. But, there were "practices"
in place that should have prevented "Three Mile Island", etc.

Unfortunately, the folks designing these things have less and less
time, less and less *motivation* and less and less *capability*
for making "robust" products.

My DTV tuner shows *two* "9-1" channels.

Years ago, we would design devices that were (comparatively speaking)
*smart*. They could diagnose their own faults. They could assist
the technician in troubleshooting (set up scope loops, etc.).
Now, everything is reduced to the equivalent of an idiot light
"Service Required" -- and, often, that light isn't even present!
The device just "acts funny". And, since users often don't know
how it truly *should* work, they can't AUTHORITATIVELY complain/deduce
that it *is* malfunctioning.

(how many VCR's blink 12:00? Do you have to be a rocket scientist
to set the clock on a VCR???)

I have a Zune media player (movies, music, etc.). I am convinced the
hard drive inside it is dying. Instead of a diagnostic message to
that effect appearing on the LARGE, COLOR, FULL GRAPHIC DISPLAY, the
device sits there trying to read from the disk endlessly (locking
up in the process). "Um, if it can't get the data on the first,
second or even three hundredth attempt, what makes you think it will
get it on the 9 millionth attempt two days from now???"

Instead of helping the consumer determine that he has a p[roblem
(or, better yet, RECOVERING from that problem), it sits there
frustrating the user and leaving him with no alternative other
than to:
- call tech support (in some third-world country, no doubt)
- google for similar symptoms
- discard it in frustration

"D Yuniskis" wrote in message ...

Hi Charles,

Charles wrote:
Consumers are becoming more clueless as software takes over their lives.

The problem is that consumers don't *want* to know how things
work or *should* work.

Well, if you meant that they are not willing to expend any effort to learn
about their possessions, then you are correct.

And, they don't "vote with their wallet".
They get a crappy product and they either live with it (possibly
not even knowing how crappy it is!) or toss it out and buy another
(probably EQUALLY as crappy)

I shudder at the amount of functional items that are returned, or re-sold,
or sent to landfills and recycling centers. The waste is a pox on our
future. The planet Earth is a finite resource!

This is a problem that is becoming more serious. If the doctors and
nurses and technicians in a modern operating room get confused or misled
by software glitches, it could be really, really serious. Has already
happened.

Google "Therac".

Unfortunately, the folks designing these things have less and less
time, less and less *motivation* and less and less *capability*
for making "robust" products.

Nor are they concerned about tomorrow, unless it's about their stock
options.

My DTV tuner shows *two* "9-1" channels.

The -1 channels here are not always available (high-def) and there is no
discernible rule of thumb to guide one as to why.

- call tech support (in some third-world country, no doubt)
- google for similar symptoms
- discard it in frustration

Toss it out. That's what too many folks are doing. Horrible!

How many VCR's blink 12:00? Do you have to be a rocket scientist
to set the clock on a VCR???

In some cases, yes. Some had setting procedures that went beyond
unbelievable.

On Fri, 10 Dec 2010 07:11:18 -1000, "John Keiser"
wrote:

I am in Hawaii where power surges are unfortunately common.

I live in the forest in the Santa Cruz Mountains. When the wind blows
or it rains, the branches and the power lines tend to meet, resulting
in power glitches.

If it makes you feel any better (probably not, but worth a try), after
every storm, I get a few calls from customers with hung network and
entertainment equipement. DSL modems, cable modems, routers,
switches, IP phones, wireless, computahs, security systems, DVR's,
printers, TIVO, etc. Just about anything with a microprocessor inside
can be made to hang. D Yuniskis covered races and hazzards so I won't
go there. Add to that the joy of memory (RAM) glitches. When the
power fluctuates, one of the most sensitive components is the common
serial or dynamic RAM commonly found in almost everything. A
momentary magnetic pulse from a nearby power xformer is usually
sufficient to produce a large enough field to flip a few bits. You
may not even notice that a few bits have been flipped until perhaps
days after the power glitch, when the operating system decides to use
those memory cells, and finds them in a bizarre state. This is why
many servers have ECC (error correcting) RAM.

The problem of unpredictable processor operation is well known as are
some of the band-aids. For low end hardware, usually nothing is done.
Just power cycle the box if it hangs. Some clever programmers add in
a watchdog timer, which monitors the state of some manner of commonly
updated register (i.e. the RTC) and reboots the device if it goes
comatose. While clever, it's not very reliable as the dead-mans timer
is part of the same processor that it's trying to protect. An
external watchdog timer works much better. It usually receives a 1
PPS (one pulse per sec) signal from the processor. If that
disappears, it's reboot time.

It isn't just power line glitches that cause hangs. Cosmic rays,
alpha particles from radioactive components, external fields, and bit
rot all contribute to the general lack of uptime.

Anyway, try not to worry too much. Features and functions are added
faster than bugs get fixed, so reliability and uptime rapidly some
minimum acceptable value. This value is usually set by when the
support phone starts ringing. When the customer complaints arrive,
it's probably time to fix the problem. Otherwise, few people complain
about ocassional hangs, crashes, and reboots.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

Follow up in case anyone else has this problem:
While unplugging the TV seemed to restore operation, the next morning the
screen was all pink but the menu functioned fine. Toggling "Factory Reset"
seems to have done the trick permanently.
"John Keiser" wrote in message
news:Pt2dndwbSd3dwp_QnZ2dnUVZ_u2dnZ2d@powerusenet. com...
I am in Hawaii where power surges are unfortunately common. Having lost
several PC power supplies, I now use line conditioning battery backup units
to protect my PCs.
Several months ago I salvaged a Westington flat screen [LTV-32w6 HD] that
had been abandoned because the tuner failed. As the tuner is part of the
motherboard I didn't fix it was easier to use an external VCR as the
tuner. TV functions fine. I assume the tuner died in a power surge.
Yesterday, the power failed and I awoke to find that the TV had turned
itself on but no sound. Toggling mute and adding external speakers did
not work. I assumed the worst but guessed that maybe this was a
microprocessor locked into mute. I unplugged the set and tried again
after 15 minutes. Sound was restored. Whew!
I wonder how many consumers would be so lucky? Is this type of
sensitivity common? [I have a nice old 32inch CRT that has been immmune
from these problems and provides a great picture.] I'll probably add a
line conditioner, but, really, are consumers expected to be that cautious?