17 Jul
2010
17 Jul
'10
10:46 p.m.
Hello all,
Early this week one of the three 'rendering' PCs of the WFS
system in the Sala Bianca failed. It just appeared completely
dead and didn't even try to boot when the power button was
pressed, but the standby power (for the network interface)
was available.
I suspected the power supply, so ordered a new one which
arrived two days ago. Installed it and things worked again.
But now comes the interesting part. While installing the new
PS, I also disconnected the wires to the power button, and
to test I just used a screwdriver to short the two pins that
normally connect to it. But when I reconnected the power button
the PC switched off after a few seconds. So it seemed as if the
power button was permanently being pressed. I again installed
the old PS, and things worked as long as the power button was
not connected.
Measuring the power button switch with a multimeter showed
an unstable resistance value of between 1 and 3k while it
was not pressed. So I removed the thing, which turned out
to be a cheap miniature switch, a little cube of around 8
mm size. I opened and disassembled it, and noticed that the
contacts had some black dirt on them. Cleaned with aceton
and reassembled, and things worked perfectly again.
What I don't understand is how the contacts got so dirty.
If a resistance of a few kOhm is enough to make it look
as a closed contact then it can't be handling large currents,
so there should not be any arcing. And the construction of
the thing is such that it is virtually closed, no dust or
whatever could ever creep in.
Still it's quite sobering that this cheap 0.30 Euro thing
was capable of bringing down a 1600 Euro workstation...
Who would suspect a switch to fail in this way ?
Ciao,
--
Je veux que la mort me trouve plantant mes choux, mais
nonchalant d’elle, et encore plus de mon jardin imparfait.
(Michel de Montaigne)
17 Jul
17 Jul
11:07 p.m.
On Sat, 17 Jul 2010 22:46:01 +0200
fons(a)kokkinizita.net wrote:
Still it's quite sobering that this cheap 0.30
Euro thing
was capable of bringing down a 1600 Euro workstation...
Who would suspect a switch to fail in this way ?
Ciao,
Not the least bit surprised. In my industry crappy membrane switches
bring £3,000,000 printing presses to a halt :(
P.S.
Doesn't help that operators tend to poke them with allen keys,
screwdrivers, pens or whatever else they may happen to have in their
hand at the time.
--
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
11:21 p.m.
On Sat, 2010-07-17 at 22:07 +0100, Folderol wrote:
On Sat, 17 Jul 2010 22:46:01 +0200
fons(a)kokkinizita.net wrote:
I'm also not surprised, even for very expensive switches at least the
debouncing isn't that good as it should be.
Still it's quite sobering that this cheap
0.30 Euro thing
was capable of bringing down a 1600 Euro workstation...
Who would suspect a switch to fail in this way ?
Ciao,
Not the least bit surprised. In my industry crappy membrane switches
bring £3,000,000 printing presses to a halt :(
11:23 p.m.
On Sat, Jul 17, 2010 at 10:07:28PM +0100, Folderol wrote:
On Sat, 17 Jul 2010 22:46:01 +0200
fons(a)kokkinizita.net wrote:
Membrane switches should be banned from industrial equipment
by law (health and safety regulations come to mind). Any switch
used in such an environment should require a force of at least
10 N to operate it, and be designed to survice being hit by a
20 pound hammer.
Still it's quite sobering that this cheap
0.30 Euro thing
was capable of bringing down a 1600 Euro workstation...
Who would suspect a switch to fail in this way ?
Ciao,
Not the least bit surprised. In my industry crappy membrane switches
bring £3,000,000 printing presses to a halt :( Doesn't help that operators tend to poke them with
allen keys,
screwdrivers, pens or whatever else they may happen to have in their
hand at the time.
The strange thing about that PC power switch is that it is
almost never used. The rendering machines wake up by a LAN
message from the master, and shutdown by remote control as
well. They are never touched.
Ciao,
--
Je veux que la mort me trouve plantant mes choux, mais
nonchalant d’elle, et encore plus de mon jardin imparfait.
(Michel de Montaigne)
11:28 p.m.
On Sat, 2010-07-17 at 23:23 +0200, fons(a)kokkinizita.net wrote:
The strange thing about that PC power switch is that
it is
almost never used. The rendering machines wake up by a LAN
message from the master, and shutdown by remote control as
well. They are never touched.
That makes it more easy for particulate matter to hurt the switch. Using
a switch will shorten it's live time, but never using it will do it too,
because when you use the switch, also dirt gets hurt, not only the
switch.
18 Jul
18 Jul
12:32 a.m.
On Sat, 17 Jul 2010 23:27:46 +0200
Ralf Mardorf <ralf.mardorf(a)alice-dsl.net> wrote:
On Sat, 2010-07-17 at 23:23 +0200,
fons(a)kokkinizita.net wrote:
Hmmm.
I would say the black deposit was almost certainly silver oxide, and
silver contact switches are not suitable for zero wiping action - indeed
the only safe ones I know of are gold ones. See, it's all your fault.
No use means no wipe :)
However I'm slightly puzzled. I confess to not knowing *precisely* the
start-up operation of these PSUs, but wonder of the contacts are
normally closed, and start signal is from their break action.
Dirty switches and relays don't usually inadvertently close, but they
very frequently randomly open or partially open, and that would
fully account for the symptoms you saw.
There was a time when us poor trainees had to learn all about contact
materials, ratings, actions, yada yada :(
Kids today don't know how well off they are :P
--
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
The strange thing about that PC power switch is
that it is
almost never used. The rendering machines wake up by a LAN
message from the master, and shutdown by remote control as
well. They are never touched.
That makes it more easy for particulate matter to hurt the switch. Using
a switch will shorten it's live time, but never using it will do it too,
because when you use the switch, also dirt gets hurt, not only the
switch.
12:45 a.m.
On Sat, 2010-07-17 at 23:32 +0100, Folderol wrote:
I would say the black deposit was almost certainly
silver oxide
More likely, but particulate matter.
But the important thing still might be:
No use means no wipe :)
It's more safe not to add a switch if it isn't used. Finagle's law:
'Anything that can go wrong, will—at the worst possible moment'
There was a time when us poor trainees had to learn
all about contact
materials, ratings, actions, yada yada :(
Kids today don't know how well off they are :P
:D
3:35 p.m.
Hi All
Just listened to the music from this sig,
Very nice all from a Linux workstation I assume.
Cheers
Bob
Blueslsd
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev(a)lists.linuxaudio.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev
4:17 p.m.
On Sun, 18 Jul 2010 14:35:41 +0100
Frank Smith <frsmith(a)gmail.com> wrote:
Hi All
Just listened to the music from this sig,
Very nice all from a Linux workstation I assume.
Cheers
Bob
Blueslsd
Thank you very much :)
Yes, I'm a totally Linux house (apart from an ancient Acorn machine that
sulks in the corner)
--
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
17 Jul
17 Jul
11:17 p.m.
On Sat, 2010-07-17 at 22:46 +0200, fons(a)kokkinizita.net wrote:
Hello all,
Early this week one of the three 'rendering' PCs of the WFS
system in the Sala Bianca failed. It just appeared completely
dead and didn't even try to boot when the power button was
pressed, but the standby power (for the network interface)
was available.
I suspected the power supply, so ordered a new one which
arrived two days ago. Installed it and things worked again.
But now comes the interesting part. While installing the new
PS, I also disconnected the wires to the power button, and
to test I just used a screwdriver to short the two pins that
normally connect to it. But when I reconnected the power button
the PC switched off after a few seconds. So it seemed as if the
power button was permanently being pressed. I again installed
the old PS, and things worked as long as the power button was
not connected.
Measuring the power button switch with a multimeter showed
an unstable resistance value of between 1 and 3k while it
was not pressed. So I removed the thing, which turned out
to be a cheap miniature switch, a little cube of around 8
mm size. I opened and disassembled it, and noticed that the
contacts had some black dirt on them. Cleaned with aceton
and reassembled, and things worked perfectly again.
What I don't understand is how the contacts got so dirty.
Particulate matter!
If a resistance of a few kOhm is enough to make it look
as a closed contact then it can't be handling large currents,
so there should not be any arcing. And the construction of
the thing is such that it is virtually closed, no dust or
whatever could ever creep in.
Still it's quite sobering that this cheap 0.30 Euro thing
was capable of bringing down a 1600 Euro workstation...
Who would suspect a switch to fail in this way ?
Ciao,
The Yamaha SPX 90 II has got mechanical relays for the audio signal. One
channel had a loss of high frequencies. The relays seem to be ok, but
one relay wasn't ok.
I add switches to all those devices that will keep on standby mode.
Sometimes those switches don't come through 2 month.
If something fails today I always check mechanical elements first.
Btw. in Germany the following three products of the company 'Kontakt
Chemie' sometimes even can repair fader.
First use Kontakt Chemie 60 to clean, then use Kontakt Chemie WL to
flush out and after this, to avoid what's called 'fader death', make the
fader move smoothly again by using Kontakt Chemie 61. And only buy small
aerosol cans, the content crawl through the folds of the cans.
Debouncing and live time of switches always is a gambling game.
12:19 a.m.
On Sat, 2010-07-17 at 18:04 -0400, drew Roberts wrote:
On Saturday 17 July 2010 17:17:05 Ralf Mardorf wrote:
In Germany they would arrest you today because of the pollutive bad
efficacy the power supply had. Perhaps the keyboard was better than the
keyboard of the Sinclair ZX80.
Debouncing and live time of switches always is a
gambling game.
Makes me remember key debouncing issues with the TRS-80 Model I keyboards...
drew
12:23 a.m.
On Sat, 2010-07-17 at 18:04 -0400, drew Roberts wrote:
On Saturday 17 July 2010 17:17:05 Ralf Mardorf wrote:
PS:
http://www.classiccmp.org/dunfield/sinclair/h/zx80.jpg
INTEGRAL FUNCTIONS
CHR$
STR$
TL$
PEEK
...
:D
Debouncing and live time of switches always is a
gambling game.
Makes me remember key debouncing issues with the TRS-80 Model I keyboards...
drew 
4:59 a.m.
On Saturday, July 17, 2010 10:59:08 pm drew Roberts did opine:
On Saturday 17 July 2010 17:17:05 Ralf Mardorf wrote:
I think that should make both of us genuine old farts. :)
Debouncing and live time of switches always is a
gambling game.
Makes me remember key debouncing issues with the TRS-80 Model I
keyboards...
drew _______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev(a)lists.linuxaudio.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Win98 is called Win98 because 98% of all hardware components will need
driver updates.
4:07 p.m.
On Saturday 17 July 2010 22:59:51 Gene Heskett wrote:
On Saturday, July 17, 2010 10:59:08 pm drew Roberts
did opine:
I started in my mid to late teens but I am getting there. Thankfully.
all the best,
drew
On Saturday 17 July 2010 17:17:05 Ralf Mardorf
wrote:
I think that should make both of us genuine old farts. :) Debouncing and live time of switches always is a
gambling game.
Makes me remember key debouncing issues with the TRS-80 Model I
keyboards...
drew
4:49 p.m.
On Sunday, July 18, 2010 10:47:23 am drew Roberts did opine:
On Saturday 17 July 2010 22:59:51 Gene Heskett wrote:
And I was in the 40's by then,, I'll be 76 in Oct, if this batch of
fencepost holes don't finish me first. A type 2 Diabetic, my warranty
expired 30 years ago. ;-)
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
A farmer is a man outstanding in his field.
On Saturday, July 17, 2010 10:59:08 pm drew
Roberts did opine:
I started in my mid to late teens but I am getting there. Thankfully.
all the best,
drew On Saturday 17 July 2010 17:17:05 Ralf Mardorf
wrote:
I think that should make both of us genuine old farts. :) Debouncing and live time of switches always is a
gambling game.
Makes me remember key debouncing issues with the TRS-80 Model I
keyboards...
drew
5:05 p.m.
On Sun, 18 Jul 2010 10:49:24 -0400
Gene Heskett <gene.heskett(a)gmail.com> wrote:
And I was in the 40's by then,, I'll be 76 in
Oct, if this batch of
fencepost holes don't finish me first. A type 2 Diabetic, my warranty
expired 30 years ago. ;-)
Woo! There's hope for the rest of us then :)
--
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
5:14 p.m.
On Sunday, July 18, 2010 11:08:03 am Folderol did opine:
On Sun, 18 Jul 2010 10:49:24 -0400
Gene Heskett <gene.heskett(a)gmail.com> wrote:
I never doubted that for an instant. There are some real brains on this
list. If osmosis still worked on this old wet ram, I might actually learn
something.
Sometimes this audio scene reminds me of a 'Marge' cartoon I have on the
wall, which says "Just think, in 40 years we'll have all these tatooed old
lady's running around, and Rap Music will be the golden oldies" Scary
thought to an old country music fan. ;-)
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
"You've got to think about tomorrow!"
"TOMORROW! I haven't even prepared for *_________yesterday*
yet!"
And I was in the 40's by then,, I'll be
76 in Oct, if this batch of
fencepost holes don't finish me first. A type 2 Diabetic, my warranty
expired 30 years ago. ;-)
Woo! There's hope for the rest of us then :)
8:30 p.m.
On Sun, 2010-07-18 at 11:14 -0400, Gene Heskett wrote:
On Sunday, July 18, 2010 11:08:03 am Folderol did
opine:
The great Johnny Cash had his revival because of people that had to do
with an US label that indeed is from jazz and late more from heavy
metal, but especially a very important rap primary rock did sample a
heavy metal band from this label. 'Don't believe the hype', but believe
me ;). Rap isn't closely related because of sampling, but because of a
community of people in my age, to the revival of Johnny Cash.
Those old Punx and HipHop folks have roots, off cause MC5 and others,
but also Blue Grass and Western and Country ... not those KKK crowed,
but e.g. Johnny Cash.
Rap isn't that bad at all. There's Rap and Rap, but also Western and
Country can differ between trash and good music :).
On Sun, 18 Jul 2010 10:49:24 -0400
Gene Heskett <gene.heskett(a)gmail.com> wrote:
I never doubted that for an instant. There are some real brains on this
list. If osmosis still worked on this old wet ram, I might actually learn
something.
Sometimes this audio scene reminds me of a 'Marge' cartoon I have on the
wall, which says "Just think, in 40 years we'll have all these tatooed old
lady's running around, and Rap Music will be the golden oldies" Scary
thought to an old country music fan. ;-) And I was in the 40's by then,, I'll be
76 in Oct, if this batch of
fencepost holes don't finish me first. A type 2 Diabetic, my warranty
expired 30 years ago. ;-)
Woo! There's hope for the rest of us then :) 
11:36 p.m.
On 18 July 2010 19:30, Ralf Mardorf <ralf.mardorf(a)alice-dsl.net> wrote:
The great Johnny Cash had his revival because of
people that had to do
with an US label that indeed is from jazz and late more from heavy
metal, but especially a very important rap primary rock did sample a
heavy metal band from this label. 'Don't believe the hype', but believe
me ;). Rap isn't closely related because of sampling, but because of a
community of people in my age, to the revival of Johnny Cash.
I just love the way that google autocompletes elvis was a hero to most
when you start typing it in as a search term.
19 Jul
19 Jul
4:46 p.m.
On Sunday 18 July 2010 11:14:26 Gene Heskett wrote:
Scary
thought to an old country music fan. ;-)
Who do you like? My dad was a fan and was always playing it around the house
as well as taking us on trips to the opry and what not.
Some of his tastes rubbed off on me.
drew
8:34 p.m.
On Monday, July 19, 2010 02:28:56 pm drew Roberts did opine:
On Sunday 18 July 2010 11:14:26 Gene Heskett wrote:
John Cash was the best, but his brother Tommy whom I have also met a couple
of times is a long way down the list. And of course I'll be in love with
Loretta Lynn for the rest of my days. The favorite list however, is quite
long so I won't bore this list with it.
Scary
thought to an old country music fan. ;-)
Who do you like? My dad was a fan and was always playing it around the
house as well as taking us on trips to the opry and what not. Some of his tastes rubbed off on me.
drew
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev(a)lists.linuxaudio.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Actually, what I'd like is a little toy spaceship!!
10:25 a.m.
On 18 July 2010 16:05, Folderol <folderol(a)ukfsn.org> wrote:
On Sun, 18 Jul 2010 10:49:24 -0400
Gene Heskett <gene.heskett(a)gmail.com> wrote:
Cheers
Bob
And I was in the 40's by then,, I'll be
76 in Oct, if this batch of
fencepost holes don't finish me first. A type 2 Diabetic, my warranty
expired 30 years ago. ;-)
Woo! There's hope for the rest of us then :)
I now feel like a young fart at 52!!!!!!!
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev(a)lists.linuxaudio.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev
10:32 a.m.
On Mon, 2010-07-19 at 09:25 +0100, Frank Smith wrote:
On 18 July 2010 16:05, Folderol
<folderol(a)ukfsn.org> wrote:
On Sun, 18 Jul 2010 10:49:24 -0400
Gene Heskett <gene.heskett(a)gmail.com> wrote:
when i feel like a fart, i generally don't tell anyone ;)
And I was in the 40's by then,, I'll be
76 in Oct, if this
batch of
fencepost holes don't finish me first. A
type 2 Diabetic,
my warranty
expired 30 years ago. ;-)
Woo! There's hope for the rest of us then :)
I now feel like a young fart at 52!!!!!!! 
17 Jul
17 Jul
11:19 p.m.
On Saturday 17 July 2010 22:46:01 fons(a)kokkinizita.net wrote:
Still it's quite sobering that this cheap 0.30
Euro thing
was capable of bringing down a 1600 Euro workstation...
Who would suspect a switch to fail in this way ?
For these "just on" installs, I change the bios to just power-on as soon as
power is there and either put the power-button (and the reset-button!) inside
the closure or just don't connect them.
Arnold
18 Jul
18 Jul
4:56 a.m.
On Saturday, July 17, 2010 10:47:58 pm fons(a)kokkinizita.net did opine:
Hello all,
Early this week one of the three 'rendering' PCs of the WFS
system in the Sala Bianca failed. It just appeared completely
dead and didn't even try to boot when the power button was
pressed, but the standby power (for the network interface)
was available.
I suspected the power supply, so ordered a new one which
arrived two days ago. Installed it and things worked again.
But now comes the interesting part. While installing the new
PS, I also disconnected the wires to the power button, and
to test I just used a screwdriver to short the two pins that
normally connect to it. But when I reconnected the power button
the PC switched off after a few seconds. So it seemed as if the
power button was permanently being pressed. I again installed
the old PS, and things worked as long as the power button was
not connected.
Measuring the power button switch with a multimeter showed
an unstable resistance value of between 1 and 3k while it
was not pressed. So I removed the thing, which turned out
to be a cheap miniature switch, a little cube of around 8
mm size. I opened and disassembled it, and noticed that the
contacts had some black dirt on them. Cleaned with aceton
and reassembled, and things worked perfectly again.
What I don't understand is how the contacts got so dirty.
If a resistance of a few kOhm is enough to make it look
as a closed contact then it can't be handling large currents,
so there should not be any arcing. And the construction of
the thing is such that it is virtually closed, no dust or
whatever could ever creep in.
Still it's quite sobering that this cheap 0.30 Euro thing
was capable of bringing down a 1600 Euro workstation...
Who would suspect a switch to fail in this way ?
Ciao,
Some lubricant obviously made its way in there, and one would have to
assume that the switched current was sufficient to cause a microscopic
arcing, which will in time create a smoke film on the internals, which is
what you were measuring, and which caused the PSU to think the button was
pressed full time. Lubricants are a good idea only on a circuit that can
be called a dry circuit, where dry=microamp currents at very low voltages.
Washing it out with acetone was ok, but I would probably have reached for a
can of paint thinning alcohol as it is less likely to degrade the plastics.
Yup, I am a C.E.T., with 60 years of that sort of trouble shooting.
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
God is subtle, but he is not malicious.
-- Albert Einstein
11:14 a.m.
On Sat, Jul 17, 2010 at 10:56:47PM -0400, Gene Heskett wrote:
Some lubricant obviously made its way in there, and
one would have to
assume that the switched current was sufficient to cause a microscopic
arcing, which will in time create a smoke film on the internals, which is
what you were measuring, and which caused the PSU to think the button was
pressed full time. Lubricants are a good idea only on a circuit that can
be called a dry circuit, where dry=microamp currents at very low voltages.
Ah, yes, these plastic things are often lubricated.
Washing it out with acetone was ok, but I would
probably have reached for a
can of paint thinning alcohol as it is less likely to degrade the plastics.
I know, but the acetone was all I had available...
Ciao,
--
Je veux que la mort me trouve plantant mes choux, mais
nonchalant d’elle, et encore plus de mon jardin imparfait.
(Michel de Montaigne)
11:28 a.m.
On Sun, 2010-07-18 at 11:14 +0200, fons(a)kokkinizita.net wrote:
On Sat, Jul 17, 2010 at 10:56:47PM -0400, Gene Heskett
wrote:
Fruit acids or pure alcohols are effective and relatively harmless, but
most effective are products by chemical companies, there are cleaners
with qualities comparable to penetrating oil, but made to fit to
electrical properties. Those cleaners will clean, resp. repair and
protect.
Some lubricant obviously made its way in there,
and one would have to
assume that the switched current was sufficient to cause a microscopic
arcing, which will in time create a smoke film on the internals, which is
what you were measuring, and which caused the PSU to think the button was
pressed full time. Lubricants are a good idea only on a circuit that can
be called a dry circuit, where dry=microamp currents at very low voltages.
Ah, yes, these plastic things are often lubricated.
Washing it out with acetone was ok, but I would
probably have reached for a
can of paint thinning alcohol as it is less likely to degrade the plastics.
I know, but the acetone was all I had available...
Ciao,
3:33 p.m.
On Sunday, July 18, 2010 09:25:27 am Ralf Mardorf did opine:
On Sun, 2010-07-18 at 11:14 +0200,
fons(a)kokkinizita.net wrote:
True for the most part, but please do not place the common Freon TF in that
category when magnetic media is involved. 15 years ago at the tv station,
I got tired of paying for Freon-TF by the gallon, and cleaning the heads on
all our VCR's 2-4x daily, and tried cleaning one with paint thinner alcohol
from ACE Hardware. I didn't have to clean it again for a week! So I
switched cleaning agents on the spot. And it turned out that Freon-TF was
also much harder on the elastomer parts like pinch rollers. I cut the time
spent cleaning heads and rollers by 90%. Roller replacements went way down
too.
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Humor in the Court:
Q. Doctor, did you say he was shot in the woods?
A. No, I said he was shot in the lumbar region.
On Sat, Jul 17, 2010 at 10:56:47PM -0400, Gene
Heskett wrote:
Fruit acids or pure alcohols are effective and relatively harmless, but
most effective are products by chemical companies, there are cleaners
with qualities comparable to penetrating oil, but made to fit to
electrical properties. Those cleaners will clean, resp. repair and
protect.
Some lubricant obviously made its way in there,
and one would have
to assume that the switched current was sufficient to cause a
microscopic arcing, which will in time create a smoke film on the
internals, which is what you were measuring, and which caused the
PSU to think the button was pressed full time. Lubricants are a
good idea only on a circuit that can be called a dry circuit, where
dry=microamp currents at very low voltages.
Ah, yes, these plastic things are often lubricated.
Washing it out with acetone was ok, but I would
probably have
reached for a can of paint thinning alcohol as it is less likely to
degrade the plastics.
I know, but the acetone was all I had available...
Ciao,
3:50 p.m.
On Sun, Jul 18, 2010 at 09:33:25AM -0400, Gene Heskett wrote:
True for the most part, but please do not place the
common Freon TF in that
category when magnetic media is involved. 15 years ago at the tv station,
I got tired of paying for Freon-TF by the gallon, and cleaning the heads on
all our VCR's 2-4x daily, and tried cleaning one with paint thinner alcohol
from ACE Hardware. I didn't have to clean it again for a week! So I
switched cleaning agents on the spot. And it turned out that Freon-TF was
also much harder on the elastomer parts like pinch rollers. I cut the time
spent cleaning heads and rollers by 90%. Roller replacements went way down
too.
True. I've never seen Freon being used for head cleaning except on
the old 2" video machines where it coud be sprayed on the moving
tape (even on-air in some cases) just before the rotating head.
For everything else alcohol was used.
Ciao,
--
Je veux que la mort me trouve plantant mes choux, mais
nonchalant d’elle, et encore plus de mon jardin imparfait.
(Michel de Montaigne)
4:04 p.m.
On Sun, 2010-07-18 at 15:50 +0200, fons(a)kokkinizita.net wrote:
On Sun, Jul 18, 2010 at 09:33:25AM -0400, Gene Heskett
wrote:
Alcohol moreover is less expensive and for those 'opened' spinning
things penetrating qualities aren't needed.
True for the most part, but please do not place
the common Freon TF in that
category when magnetic media is involved. 15 years ago at the tv station,
I got tired of paying for Freon-TF by the gallon, and cleaning the heads on
all our VCR's 2-4x daily, and tried cleaning one with paint thinner alcohol
from ACE Hardware. I didn't have to clean it again for a week! So I
switched cleaning agents on the spot. And it turned out that Freon-TF was
also much harder on the elastomer parts like pinch rollers. I cut the time
spent cleaning heads and rollers by 90%. Roller replacements went way down
too.
True. I've never seen Freon being used for head cleaning except on
the old 2" video machines where it coud be sprayed on the moving
tape (even on-air in some cases) just before the rotating head.
For everything else alcohol was used.
Ciao, 
2:37 p.m.
On 07/17/2010 10:46 PM, fons(a)kokkinizita.net wrote:
What I don't understand is how the contacts got so
dirty.
If a resistance of a few kOhm is enough to make it look
as a closed contact then it can't be handling large currents,
so there should not be any arcing. And the construction of
the thing is such that it is virtually closed, no dust or
whatever could ever creep in.
it can't be totally sealed, as that would require an expensive gasket.
my guess is that the way servers are designed, air is drawn in through
the front (the "cold aisle" in datacenter lore), and expelled through
the rear (the "hot aisle"). after some years of use, it's not so
unlikely for gunk to accumulate pretty much anywhere in the path of the
airflow.
and the conductivity of pure industry-strength gunk should never be
underestimated.
btw, if the bios does not allow the boards to be configured as "always
on after power loss" (common on older hardware), a capacitor in place of
the momentary power switch works nicely, provided its charging current
has dropped to zero before the bios thinks it's a
more-than-four-seconds-turn-me-off event.
3:28 p.m.
On Sun, 2010-07-18 at 14:37 +0200, Jörn Nettingsmeier wrote:
On 07/17/2010 10:46 PM, fons(a)kokkinizita.net wrote:
Just for fun I used the German Google to search for the switch issue. It
seems to be something that happens very often :D. Wow, my PC case is
that old, that I had to manipulate the LED jacks, because they don't fit
to modern mobos, but the switches never were broken.
What's a good value for a capacitor?
Btw. I pushed the momentary switch while running a GNOME session on Suse
11.2. As expected the ShutDown-Restart-Suspend-Hibernate menu appeared.
I closed the menu and pushed the momentary switch again, but the the
computer turned off, without doing a shutdown.
What I don't understand is how the contacts
got so dirty.
If a resistance of a few kOhm is enough to make it look
as a closed contact then it can't be handling large currents,
so there should not be any arcing. And the construction of
the thing is such that it is virtually closed, no dust or
whatever could ever creep in.
it can't be totally sealed, as that would require an expensive gasket.
my guess is that the way servers are designed, air is drawn in through
the front (the "cold aisle" in datacenter lore), and expelled through
the rear (the "hot aisle"). after some years of use, it's not so
unlikely for gunk to accumulate pretty much anywhere in the path of the
airflow.
and the conductivity of pure industry-strength gunk should never be
underestimated.
btw, if the bios does not allow the boards to be configured as "always
on after power loss" (common on older hardware), a capacitor in place of
the momentary power switch works nicely, provided its charging current
has dropped to zero before the bios thinks it's a
more-than-four-seconds-turn-me-off event.
3:56 p.m.
On Sun, Jul 18, 2010 at 02:37:54PM +0200, Jörn Nettingsmeier wrote:
it can't be totally sealed, as that would require
an expensive
gasket. my guess is that the way servers are designed, air is drawn
in through the front (the "cold aisle" in datacenter lore), and
expelled through the rear (the "hot aisle"). after some years of
use, it's not so unlikely for gunk to accumulate pretty much
anywhere in the path of the airflow.
and the conductivity of pure industry-strength gunk should never be
underestimated.
Yes, dust will accumulate everywhere. But this switch was well
outside the normal airflow paths, and the outside was clean.
The 'dirt' was indeed a thin film, as Gene suggested.
The machines are configure to reboot after a power failure,
but not if they think they have been switched of manually,
which was what happened.
Meanwhile the second ADI-648 power supply has gone, as the
first one during a night with several city-wide power cuts.
I'm not really impressed by that very big UPS. Or there is
something wrong with its installation.
Ciao,
--
Je veux que la mort me trouve plantant mes choux, mais
nonchalant d’elle, et encore plus de mon jardin imparfait.
(Michel de Montaigne)
4:12 p.m.
Fons,
Meanwhile the second ADI-648 power supply has gone, as
the
first one during a night with several city-wide power cuts.
Did you already do something about the extremely high temperature in the
racks?
I'm not really impressed by that very big UPS. Or
there is
something wrong with its installation.
If it's a proper UPS it should keep a log of the voltage and any
abnormal events.
Flo
--
Machines can do the work, so people have time to think.
public key DA43FEF4 x-hkp://wwwkeys.eu.pgp.net
4:43 p.m.
On Sun, Jul 18, 2010 at 04:12:22PM +0200, Florian Faber wrote:
If it's a proper UPS it should keep a log of the
voltage and any
abnormal events.
It probably does, but I'm not supposed to tinker with it;
it's in the hands of the city's technical department.
I've repeatedly asked for complete drawings of the
electricy wiring in the CdS, and I'm beginning to
suspect they don't even exist. Fact is that many parts
of the power switchboard are labeled wrongly, as are
the remotely controlled functions. And I have no idea
which parts of the audio installation are or are not
on the UPS - nobody seems to know.
As to the racks, I've inreased the spacing between units
where I could, and blower panels will be ordered. But the
main source of heat remains a block of 12 Aphex 141 DA's.
Moving them apart would require to redo the complete
internal wiring of the racks.
Ciao,
--
Je veux que la mort me trouve plantant mes choux, mais
nonchalant d’elle, et encore plus de mon jardin imparfait.
(Michel de Montaigne)
5:03 p.m.
On Sun, 18 Jul 2010 16:43:03 +0200
fons(a)kokkinizita.net wrote:
I've repeatedly asked for complete drawings of the
electricy wiring in the CdS, and I'm beginning to
suspect they don't even exist. Fact is that many parts
of the power switchboard are labeled wrongly, as are
the remotely controlled functions. And I have no idea
which parts of the audio installation are or are not
on the UPS - nobody seems to know.
This all sounds entirely normal :(
The number of times I've asked myself 'Do I really, really, REALLY want
to switch that off?'
--
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
5:07 p.m.
On 07/18/10 17:03, Folderol wrote:
The number of times I've asked myself 'Do I
really, really, REALLY want
to switch that off?'
Do it. It's better to find out in a controlled situation than the hard way.
Flo
--
Machines can do the work, so people have time to think.
public key DA43FEF4 x-hkp://wwwkeys.eu.pgp.net
4:14 p.m.
On Sun, 18 Jul 2010 15:56:36 +0200
fons(a)kokkinizita.net wrote:
Meanwhile the second ADI-648 power supply has gone, as
the
first one during a night with several city-wide power cuts.
I'm not really impressed by that very big UPS. Or there is
something wrong with its installation.
Ciao,
Is it a true on-line jobbie, or did the bean counters get in on the act
and demand a cheaper off-line one?
--
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
19 Jul
19 Jul
8:23 a.m.
Some spare time... I just *have* to wander into this one...
On July 17, 2010 04:46:01 pm fons(a)kokkinizita.net wrote:
Measuring the power button switch with a multimeter
showed
an unstable resistance value of between 1 and 3k while it
was not pressed. So I removed the thing, which turned out
to be a cheap miniature switch, a little cube of around 8
mm size. I opened and disassembled it, and noticed that the
contacts had some black dirt on them. Cleaned with aceton
and reassembled, and things worked perfectly again.
You say the switch had
conductance when not pressed?
Then that black dirt was not just dirt, it was something conductive.
It couldn't be oxide. Oxide increases the switch resistance.
Was the switch that simple membrane style I like to call
"juice bottle safety pop-up cap"? Or did it have an actuator
arm which travels when you push it?
Either way a switch with undue conductance is extremely rare.
I'd say it's a total fluke. Some conductive solder may have fallen inside.
Also, are you sure it was not an unwanted stray thin conducting solder bridge
or wire somewhere on or near the switch, or on the board it connects to?
You'd be surprised the odd things I've seen.
Cleaning 'black dirt' from the contacts should *not* have solved it
unless the 'dirt' itself was conductive.
What I don't understand is how the contacts got so dirty.
If a resistance of a few kOhm is enough to make it look
as a closed contact then it can't be handling large currents,
so there should not be any arcing.
It's a low current soft power switch. The
PSU does the heavy switching.
I would like to put in a plug for Caig Laboratories' DeoxIT chemical
products. Some of the best contact cleaner I've ever used.
And when *that* fails on stubborn oxidation and you're *still*
too lazy to disassemble the switch and clean the contacts by hand
with a *pencil* *eraser* (which is the ultimate solution), then try
spraying some powerful PC board flux remover in there.
That got me out of a few jams but watch out, it eats cosmetic plastics...
Cheers. Tim.
10:01 a.m.
On Mon, Jul 19, 2010 at 02:11:19AM -0400, Tim E. Real wrote:
You say the switch had conductance when not pressed?
Yes. Unstable resistance, changing every time the button
was pressed and released again, between 1 and 3 kOhm.
Was the switch that simple membrane style I like to
call
"juice bottle safety pop-up cap"? Or did it have an actuator
arm which travels when you push it?
The latter. It's a small (8mm) plastic cube consisting of
two parts that clip together, and a spring loaded actuator.
The fixed contacts are 'printed' on the inside (i.e. flush
with the inner surface), and two small pieces of copper
on the actuator bridge the tiny gaps between them.
Either way a switch with undue conductance is
extremely rare.
Indeed. I did not expect it ! Nor did I expect such a low Q
component in a workstation of that price. Even a simple but
real 'microswitch' would probably never fail in this way.
I'd say it's a total fluke. Some conductive
solder may have fallen inside.
There's no space that even a very tiny drop of solder could pass
through.
Also, are you sure it was not an unwanted stray thin
conducting solder bridge
or wire somewhere on or near the switch, or on the board it connects to?
Pretty sure of that.
You'd be surprised the odd things I've seen.
Cleaning 'black dirt' from the contacts should *not* have solved it
unless the 'dirt' itself was conductive.
Apparently it was.
Ciao,
--
FA
There are three of them, and Alleline.
5269
days inactive
5271
days old
linux-audio-dev@lists.linuxaudio.org
40 comments
12 participants
participants (12)
-
Arnold Krille -
drew Roberts -
Florian Faber -
Folderol -
fons＠kokkinizita.net -
Frank Smith -
Gene Heskett -
Geoff Beasley -
James Morris -
Jörn Nettingsmeier -
Ralf Mardorf -
Tim E. Real