Shortest period to switch off electronic equipent for before switching on

On Sat, 08 Apr 2017 10:33:44 +0100, pamela wrote:

As a rule of thumb, what's the shortest period to switch off
electronic equipment for a reset before switching on?

My usual advice on this is "Switch it off, take a deep breath, and
switch it back on again".

Rod.

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


"pamela" wrote in message
...
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.

On 08/04/2017 22:52, Roderick Stewart wrote:
On Sat, 08 Apr 2017 10:33:44 +0100, pamela wrote:

As a rule of thumb, what's the shortest period to switch off
electronic equipment for a reset before switching on?

My usual advice on this is "Switch it off, take a deep breath, and
switch it back on again".

Rod.

I used to tell customers to count to twenty, except for Mrs
Wolfe*schlegel*stein*hausen*berger*dorff. I just used to tell her to
sign my autograph book.

Bill

On 08/04/2017 10:33, pamela wrote:
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.


Twenty years ago 5 seconds may have caused a problem due to the
possibility of surges due to mains input filters.

Often if the switch off is to cold boot crashed software then the
internal PSU voltages have to decay. My rule of thumb is 30 seconds
after any front panel LED has gone out.

--
mailto: news {at} admac {dot] myzen {dot} co {dot} uk

On 08/04/17 17:15, MJC wrote:
My Humax (old 9200T) will record even when in standby

That's why I said you must make sure there are no recordings scheduled!

In my view all devices should have a little pin hole switch that does this
for you.
It really depends on the device I think. Things like my Smart talk freeview
box almost instantaneous resets are OK if done via the little plug from the
psu on the back, but if you do it from the mains it needs a little longer as
I suspect the wall wart has some capacitors in it.

Phones are awhole other ball of nuts.
Some seem to remember crashes indefinitely. there is one which is not out
of production where the software crashes and stops the voice from working at
all, even if you take the battery out.
Sadly as nobody has the gear to reblow the software any more its a brick.
Brian

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"pamela" wrote in message
...
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.

Not many people understand computer shut down via the button either If
software has locked up or is doing odd things, then a short tap on the power
button, ie NOT the reset is normally the way to get a good shutdown. If that
fails, then hold in the power button, NOT the reset button as this normally
protects the hard drive from corruption. all these folks wo either press
reset or worse, just pull the plug out deserve the reinstall they
evenntually end up having to do.
Brian
Of course if there is a power cut this can happen anyway, and I've often
thought of putting in an uninteruptable supply to allow proper shut down.
they are not that expensive these days, and laptops of course have one built
in.
Brian

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"Davey" wrote in message
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On Sat, 08 Apr 2017 10:33:44 +0100
pamela wrote:

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.

My Humax HDR Fox T2 says to wait until you hear the HDD wind down
before turning it on again. Otherwise, I generally try to wait for 30
secs. as a rule of thumb, although I'm not always that patient. Not
that I have to reset stuff much anyway.

If they're in your home, then visitors work to your rules!

--
Davey.

On Sun, 9 Apr 2017 10:01:30 +0100, "Brian Gaff"
wrote:
[...]
Of course if there is a power cut this can happen anyway, and I've often
thought of putting in an uninteruptable supply to allow proper shut down.
they are not that expensive these days, and laptops of course have one built
in.

I've seen descriptions of uninterruptible power supplies, some
designed to keep a computer running for a useful amount of time, and
some which will actually trigger a proper shutdown in case you're not
present when a power cut occurs and only have enough battery capacity
to allow that.

It all looks fascinating, but with my realist's hat on, I have to
accept that a few weeks ago I had my first ever power cut after living
in this house for about 24 years. Absolutely everything in the house
went off for a few minutes. I've no idea why. It left one of my
bedside clocks flashing 12:00 and I missed a few minutes of something
my PVR was recording, but apart from that there were no consequences
at all. I just switched the computer on again and everything was fine.

In 24 years I've had more punctures than power cuts, more broken
glassware, more burnt fingers, more job redundancies, more tooth
fillings, just about every adverse event you could name. Ive even won
the lottery more often than I've had power cuts (regrettably only a
few quid but wins nonetheless).

I wonder what would have happened if I'd had a UPS waiting to deal
with this situation for 24 years? Would its battery still have had
charge in it? Would its electronics have worked flawlessly after all
that time? Ironically it would have been many years older than the
circuitry it was installed to protect, so I wouldn't want to put too
much faith in it, and alternatively if I'd replaced the UPS as often
as my computers, most of them would have spent their entire working
lives doing absolutely nothing.

Other people's situations may be different of course, but you'll
probably guess that however interesting it might have been to have
played with one of these things I decided not to bother.

Rod.

wrote in message
...
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).

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.

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.

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.

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

"Bill Wright" wrote in message
news
On 08/04/2017 22:52, Roderick Stewart wrote:
On Sat, 08 Apr 2017 10:33:44 +0100, pamela wrote:

As a rule of thumb, what's the shortest period to switch off
electronic equipment for a reset before switching on?

My usual advice on this is "Switch it off, take a deep breath, and
switch it back on again".

Rod.

I used to tell customers to count to twenty, except for Mrs
Wolfe*schlegel*stein*hausen*berger*dorff. I just used to tell her to sign
my autograph book.

I remember a radio sketch (no idea who did it) in which a man with a very
pronounced German accent arrived at company's reception desk and asked for
Mr Best. He was asked to spell it, which he did, using various Teutonic
words B for Berlin, E for Essen etc. The receptionist didn't know it so she
phoned someone else and spelled out the name using words that were
appropriate to her, and the call was passed round for person to person, each
using words that were relevant to them to spell out the name. Eventually she
came back to the German and said "Sorry we can't find your Mr Best" to which
he said "No, you misunderstand me. *I* am Mr Best. I want to speak to
Heinrich Beschintsky Wurtermburg Holderhasser - and he is spelled H for
holdup, E for exasperated.. etc (fade out).