Shortest period to switch off electronic equipent for before

[MJC]

In article <V-KdnUieLtZb3HfFnZ2dnUU78c_NnZ2d@brightview.co.uk>,
me@privacy.net says...

The office building where I worked had huge diesel-powered generator
to cope
with power cuts. My office was near it, and I know it wasn't tested during
office hours for five years. One day there was a power cut that affected the
whole town, and the diesel engine fired up, amid a tremendous roar and lots
of filthy black smoke. Power returned for about a minute and then there was
a huge explosion and a jet of flames. Apparently the generator couldn't
handle the load, even with the engine working as hard as it could (a good
diesel grunt!) and something caught fire, igniting the diesel tank. Turned
out that it had been specced back in the days when there wasn't a PC on
every single person's desk, and it was woefully underpowered for the modern
demands that were placed on it.

Conversely the possibly apocryphal story I heard had the generator
tested regularly. When eventually needed it ran for a few minutes and
then ran out of fuel. The protocol didn't include top-ups!

Mike.

 

[Vir Campestris]

On 09/04/2017 15:34, MJC wrote:

Conversely the possibly apocryphal story I heard had the generator
tested regularly. When eventually needed it ran for a few minutes and
then ran out of fuel. The protocol didn't include top-ups!

The one I know of is where the fuel pump was on the non-maintained
mains. All the tests were fine. But when the power went off for real so
did the fuel pump...

BTW I use 30 seconds too. 30 odd years of computers here, quite often
dealing directly with the HW designers so I could write the tests.

Andy

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[Benderthe.evilrobot]

"David Woolley" <david@ex.djwhome.demon.invalid> wrote in message
newscdcd6$mn5$1@dont-email.me...

On 09/04/17 10:01, Brian Gaff wrote:
If that
fails, then hold in the power button, NOT the reset button as this
normally
protects the hard drive from corruption.

As I understand it, a long press is handled by the hardware and forces a
dirty shutdown. If it were handled by the firmware, it could be difficult
to shut down a battery powered device which had locked up. RESET should be
more gentle than a long press.

AIUI: A short press is one way of a normal shutdown - sometimes you have to
press it a little longer...................


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[Benderthe.evilrobot]

<krw@notreal.com> wrote in message
news:sg5jeclipaol2ejgd0tuivrostvvad23bt@4ax.com...

On Sat, 8 Apr 2017 20:17:20 +0100, "Benderthe.evilrobot"
Benderthe.evilrobot@virginmedia.com> wrote:


"pamela" <invalid@nospam.com> wrote in message
news:XnsA7516B728743CD4AM2@81.171.92.183...
As a rule of thumb, what's the shortest period to switch off
electronic equipment for a reset before switching on?

I mean equipment like televisions, PVR, satellite or cable boxes,
PCs, cordless phones, clock radios, etc.

My teenage relative reset our Humax PVR by switching it off and
almost INSTANTLY switched it on again. I told him to be patient
but how long should he wait for in general?

Twenty years ago 5 seconds would have been enough but nowadays some
electronic devices (like my Samsung tv) shows its power LED for 10 or
20 seconds after the mains is disconnected. Also hard drives in
Playstations and PVRs will spin on. Telling impatient kids to go and
make a cup of coffee isn't going to work.

You can't just lump everything into the same bracket - a lot of people
just
turn the TV off "cold turkey", its a lot better than leaving it unattended
on standby.

There is absolutly nothing wrong with "standby".

Anything with a hard drive can trash a file if you power down in the
middle
of a write operation.

Nonsense. There are many ways to design a device that will survive a
power failure during disk write. A bit of reserve power is probably
the best solution but a JFS works, too.

Some designs of SMPSU can go bang if you switch back on before the
reservoir
caps discharge and those with inrush surge limiting have a thermal
recovery
time for no protection - but it just stresses the components a little more
than usual. Most user manuals seem more or less unanimous for about 30s.

Only if it's designed by a moron.

There's not exactly a shortage of those - but it does tend to be more older
designs.

It does sometimes happen - pretending it doesn't won't save you.


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On Sun, 9 Apr 2017 19:55:27 +0100, "Benderthe.evilrobot"
<Benderthe.evilrobot@virginmedia.com> wrote:

krw@notreal.com> wrote in message
news:sg5jeclipaol2ejgd0tuivrostvvad23bt@4ax.com...
On Sat, 8 Apr 2017 20:17:20 +0100, "Benderthe.evilrobot"
Benderthe.evilrobot@virginmedia.com> wrote:


"pamela" <invalid@nospam.com> wrote in message
news:XnsA7516B728743CD4AM2@81.171.92.183...
As a rule of thumb, what's the shortest period to switch off
electronic equipment for a reset before switching on?

I mean equipment like televisions, PVR, satellite or cable boxes,
PCs, cordless phones, clock radios, etc.

My teenage relative reset our Humax PVR by switching it off and
almost INSTANTLY switched it on again. I told him to be patient
but how long should he wait for in general?

Twenty years ago 5 seconds would have been enough but nowadays some
electronic devices (like my Samsung tv) shows its power LED for 10 or
20 seconds after the mains is disconnected. Also hard drives in
Playstations and PVRs will spin on. Telling impatient kids to go and
make a cup of coffee isn't going to work.

You can't just lump everything into the same bracket - a lot of people
just
turn the TV off "cold turkey", its a lot better than leaving it unattended
on standby.

There is absolutly nothing wrong with "standby".

Anything with a hard drive can trash a file if you power down in the
middle
of a write operation.

Nonsense. There are many ways to design a device that will survive a
power failure during disk write. A bit of reserve power is probably
the best solution but a JFS works, too.

Some designs of SMPSU can go bang if you switch back on before the
reservoir
caps discharge and those with inrush surge limiting have a thermal
recovery
time for no protection - but it just stresses the components a little more
than usual. Most user manuals seem more or less unanimous for about 30s.

Only if it's designed by a moron.

There's not exactly a shortage of those - but it does tend to be more older
designs.

IC designers tend to do a better job protecting against weird power
cycles and a lot more system designers have been burned and learned.

It does sometimes happen - pretending it doesn't won't save you.

Of course. There are morons designing stuff all the time. Worse,
there are companies that don't care that they're making crap.

 

one opinion on electronics wear/degrade, is a function of thermal stress

 

[Stephen]

On Sun, 09 Apr 2017 08:34:56 -0400, krw@notreal.com wrote:

On Sun, 9 Apr 2017 12:21:16 +0100, "NY" <me@privacy.net> wrote:

krw@notreal.com> wrote in message
news:sg5jeclipaol2ejgd0tuivrostvvad23bt@4ax.com...
You can't just lump everything into the same bracket - a lot of people
just
turn the TV off "cold turkey", its a lot better than leaving it unattended
on standby.

There is absolutly nothing wrong with "standby".

Anything with a hard drive can trash a file if you power down in the
middle
of a write operation.

I suppose anything with disk-like storage (including flash drives) can be
trashed if the power goes off during a write, though the time during which
the files is in an inconsistent state between data sectors and sector map
may be less with solid state than a mechanical rotating disk.

Nonsense. There are many ways to design a device that will survive a
power failure during disk write. A bit of reserve power is probably
the best solution but a JFS works, too.

It depends what filesystem they use. NTFS is pretty robust but it requires a
licence to be paid to the inventors which is why a lot of PVRs use/read only
FAT/FAT32. If they are Linux-based they will be able to use filesystems
which are more robust (I'm not very clued up on Linux).

That's an economics decision. There is nothing cast in jello that
says they have to cheap out, or even use an existing FS. JFS
techniques are well known. Even if they do want to use a vulnerable
FS, a proper power system design can guarantee a safe shut down.

But I'd say that a design which trashes the file that is being written to or
the whole filesystem when the power goes off (eg due to a power-cut, which
is not totally unexpected) is a bad design: you need some form of resilience
in terms of battery-backed supply until the file write is complete and
consistent.

Exactly so. This is common with flash-based systems. The power
system has to guarantee at least the current block has been written.

Well - not really. What can you do with an app that is running and
doesnt keep files in a "safe" state?

Even some working apps dont leave files in a consistent state while
idle (although agreed that is bad design).

Less said about malware busy scribbling all over your drive to
maximise the chance of coming back to life after a reboot the
better...

The point is that an operating system cannot make assumptions about
what programs are trying to do and having "well formed" behaviour -
they need to try to be robust no matter what is mucking around, while
a disk is full and a drive is trying to remap to sort out bad sectors.

I use my Windows 7 PC as a PVR (either Windows Media Centre or NextPVR) and
I've occasionally had power cuts during recording. I've never yet lost the
recording that was being made or the filesystem of the recording HDD (NTFS).
OK, Windows may do a chkdsk repair after the PC reboots, but it seems to
sort itself out.

NTFS?

A UPS would be useful for graceful shutting down during power cuts, but it
might be more trouble that it's worth. At present my BIOS is set to reboot
the PC automatically after the power is restored. If the UPS keeps the power
up and initiates a graceful shutdown, the PC may not boot back up once the
power comes back.

My wife bought a 3kVA UPS with her big Dell PC about 10 years ago. We didn't
get round to setting up the UPS for a couple of years. By the time we did
(and after the warranty had expired, inevitably) we found that it had
virtually no battery capacity: the battery monitoring software (monitored by
USB connection) showed the battery accepting charge and gradually charging
up and eventually showing as fully charged, but as soon as the mains was
removed, the battery discharged within about 10 seconds with a nominal 40 W
lightbulb as the load. Utterly useless, and it wasn't even worth buying a
replacement battery for it because the fault may have been in the charging
circuit rather than the battery itself. APC didn't want to know when we
asked what a repair might cost, so it went in the skip - a waste of money as
it was never even used.

Always test your emergency system. When I was in IBM, they tested the
emergency generators once a month. I have no idea why they had such
in the building I was in (just offices and a few labs at that time)
but they were there, so the were tested.

It's a really good idea to test your system backups from time to time,
too. You may find the restore doesn't work. :-(

But the only true test of a restore is to actually wipe and restore on
the same hardware build - when it is too late to find out it didnt get
recorded correctly if you only have 1 machine (or 2 with different
builds)......

Moral of the story: always try any new hardware during the warranty period!

And keep the old one as a fallback....

>Anything that's important has to be tested.
Stephen Hope stephen_hope@xyzworld.com
Replace xyz with ntl to reply

 

[Stephen]

On Sun, 9 Apr 2017 15:34:01 +0100, MJC <gravity@mjcoon.plus.com>
wrote:

In article <V-KdnUieLtZb3HfFnZ2dnUU78c_NnZ2d@brightview.co.uk>,
me@privacy.net says...

The office building where I worked had huge diesel-powered generator
to cope
with power cuts. My office was near it, and I know it wasn't tested during
office hours for five years. One day there was a power cut that affected the
whole town, and the diesel engine fired up, amid a tremendous roar and lots
of filthy black smoke. Power returned for about a minute and then there was
a huge explosion and a jet of flames. Apparently the generator couldn't
handle the load, even with the engine working as hard as it could (a good
diesel grunt!) and something caught fire, igniting the diesel tank. Turned
out that it had been specced back in the days when there wasn't a PC on
every single person's desk, and it was woefully underpowered for the modern
demands that were placed on it.

Conversely the possibly apocryphal story I heard had the generator
tested regularly. When eventually needed it ran for a few minutes and
then ran out of fuel. The protocol didn't include top-ups!

We had one where someone spoofed the guage and drained the tank.

Mike.

Stephen Hope stephen_hope@xyzworld.com
Replace xyz with ntl to reply

 

>"Of course. There are morons designing stuff all the time. Worse,there are companies that don't care that they're making crap."

Worse is that of companies, at least in consumer electronics WANT them to fail. I have seen examples that are pretty sure. Like in the five volt power supply they have an extras AC feedback loop which can only make the line vary. I beleive they did it corrupt the software. But then you could get the software "update" but wouldn't they just use better capacitors, or not do anything else ? I could find the reference to it under duress, but I am saying that they spend extra copper on the board to put certain caps near the vertical IC.

Like people say the government does so many stupid things, For some of them, they have a reason.

I have also seen alot of shit in audio like that. And this did not start yesterday either. I think they want(ed) to keep their jobs, so some units must fail. Their paychecks come from the sale of new units. Same with management.

It really comes down to screwing the People.

 

">>Moral of the story: always try any new hardware during the warranty period!

And keep the old one as a fallback."

Guilty. I bought a bunch of laptops and one stayed in the box past the warranty. I have had people try that so many times that I didn't even bother calling them, I just shelfed it. Luckily later, I got to use some of the parts.