XPost: alt.os.linux.mint

pinnerite <pinnerite@gmail.com> wrote:

Around eight years ago I bought one of these strips to run my computer system. It has a master socket and seven slave sockets.

The midi-tower system plugs into the master socket. The two screens,
the printer and the sound system are plugged into the slave sockets.

When I power down at night. The strip detects this and denies power to
the accessories.

At least that is the theory and for the most part it works, except a continual hum continues to be heard from the sound system's speakers
when the system should be off.

I have changed which slave socket it is plugged into but it persists.

Mysterious.

I'd guess some kind of coupling / earth loop. eg if the power strip
switches the live but not the neutral, there could be a parasitic/induced current on the neutral side that's somehow leaking through into the
speakers. You'd need much less than would trip an RCD.

As an aside, these are quite handy as power takeoff devices for power tools,
eg to control a dust extraction vacuum:
https://youtu.be/Qo5kpKMX_Vw

and can be had on ebay as the 'Eon Power Down' for about 6-7 quid. You need
to get the computer version as the TV version has a wired puck which wakes
it up based on receiving signals from the remote control, rather than
detecting the current draw from the 'PC'. The PC version is actually
capable of switching 16A and is quite well made, so should be fine for
hungry power tools.

Theo

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XPost: alt.os.linux.mint

On 26/12/2024 14:04, pinnerite wrote:

Around eight years ago I bought one of these strips to run my computer system. It has a master socket and seven slave sockets.

The midi-tower system plugs into the master socket. The two screens,
the printer and the sound system are plugged into the slave sockets.

When I power down at night. The strip detects this and denies power to
the accessories.

At least that is the theory and for the most part it works, except a continual hum continues to be heard from the sound system's speakers
when the system should be off.

I have changed which slave socket it is plugged into but it persists.

Mysterious.

Have you tried plugging the speakers directly into the wall socket- with
as much of the other set up 'as is'?

My 'guess' is, like most people, you have 'no shortage' of mains leads
under your desk and you are getting stray, radiated, pick up rather than something from resulting from being plugged into the 'smart' socket.

While the test I suggest isn't 100% sure to clear the smart strip (if it
is radiating something it could still get into a nearby device, it it
does clear the problem, you can be near enough certain it is the
culptits.

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XPost: alt.os.linux.mint

pinnerite wrote:

Around eight years ago I bought one of these strips to run my computer system. It has a master socket and seven slave sockets.

The midi-tower system plugs into the master socket. The two screens,
the printer and the sound system are plugged into the slave sockets.

When I power down at night. The strip detects this and denies power to
the accessories.

At least that is the theory and for the most part it works, except a continual hum continues to be heard from the sound system's speakers
when the system should be off.

When you power the speakers, do you hear a relay click on?
Maybe they act as unpowered speakers when not powered, and are picking
up stray signals like that?

What if you test by powering the speakers from a different socket?

What if you unplug the speakers from the power strip altogether?

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XPost: alt.os.linux.mint

On Thu, 12/26/2024 9:04 AM, pinnerite wrote:

Around eight years ago I bought one of these strips to run my computer system. It has a master socket and seven slave sockets.

The midi-tower system plugs into the master socket. The two screens,
the printer and the sound system are plugged into the slave sockets.

When I power down at night. The strip detects this and denies power to
the accessories.

At least that is the theory and for the most part it works, except a continual hum continues to be heard from the sound system's speakers
when the system should be off.

I have changed which slave socket it is plugged into but it persists.

Mysterious.

Make and model number of sound system ?

Paul

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XPost: alt.os.linux.mint

My thought is the power strip electronics have seen better days.
Everything is made to stop working correctly.

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XPost: alt.os.linux.mint

On Thu, 12/26/2024 5:11 PM, azigni wrote:

My thought is the power strip electronics have seen better days.
Everything is made to stop working correctly.

If you do FMEA analysis of the power strip, there are
two areas of interest:

1) Lightning protection components. The discs can explode
on a direct lightning hit. Fiber barriers should be put
next to the protection discs, to prevent shards from
puncturing adjacent components. Protection components
have limited lives, as a function of the abuse they have
received. The discs can fail a lot faster in Florida USA,
the king of lightning strikes. It's not really possible
to make them completely bulletproof. Some strips have a
LED which lights, when the discs are worn out.

2) On a power switching power strip, the power relay is a
component which can fail. If the relay is a cheaper one,
the contacts may weld under load and then the strip cannot
turn off the power. The relay has to be small enough to
fit into the strip, which means even if your intentions
were honourable, you could not put a 4X rated relay in the
unit, as it would not fit. In box-shaped power strips,
there is more room for a quality relay. The form factor
plays a part in what the consumer can expect.

The thing that drives the relay coil, that circuit can be
pretty sloppy. It's possible the engineer designing it,
did not take the design seriously, and only spent one
morning working on it. You might notice on some power
strips, the threshold drifts with age, and that just
means the engineer didn't understand the circuit all
that well.

On an ATX powered PC, the Watts can be 1 watt when it is
off, yet the VA can be 7 watts, and it is the VA which
is easiest for the engineer to measure inside the power
strip. It could be, that the circuit is working perfectly
fine, and it is your mis-understanding of the circuit
draw, that is causing the functional failure. Like, say
the monitored PC, has an iPhone plugged in and charging.
Now, the power strip will not turn off the peripheral
mains outlets, because the "soft-off" power is too high.

Paul

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XPost: alt.os.linux.mint

On Fri, 12/27/2024 12:48 PM, pinnerite wrote:

On Thu, 26 Dec 2024 16:00:46 +0000
Brian <inv@lid.com> wrote:

On 26/12/2024 14:04, pinnerite wrote:

Around eight years ago I bought one of these strips to run my computer
system. It has a master socket and seven slave sockets.

The midi-tower system plugs into the master socket. The two screens,
the printer and the sound system are plugged into the slave sockets.

When I power down at night. The strip detects this and denies power to
the accessories.

At least that is the theory and for the most part it works, except a
continual hum continues to be heard from the sound system's speakers
when the system should be off.

I have changed which slave socket it is plugged into but it persists.

Mysterious.

Have you tried plugging the speakers directly into the wall socket- with
as much of the other set up 'as is'?

My 'guess' is, like most people, you have 'no shortage' of mains leads
under your desk and you are getting stray, radiated, pick up rather than
something from resulting from being plugged into the 'smart' socket.

While the test I suggest isn't 100% sure to clear the smart strip (if it
is radiating something it could still get into a nearby device, it it
does clear the problem, you can be near enough certain it is the
culptits.

My desk is a long narrow oak worktop.
Supporting it are two units built with my tender hands.
The left hand one is containing eight pull out drawers on runners.
Above that is a Fujitsu cut-sheet scanner circa 2010.
It can be driven by xsane but it is better from Windows XP, retained as
a virtual machine mainl;y for that purpose.

The right hand one is just a box that holds two mid-tower computers.
Tucked in behind them are three power strips and an ethernet switch.
Above that is a Brother colour laser printer.

What with the panasonic mobile phone, Their are cables galore.

I have just completed identifying which mains plug is which with a
black and a white marker. In the process it became clear that the
intelligent power strip has dimenture. It would be a hassle replacing
it. I shall turn off everything I can reach every night.

Thank you for all the suggestions.

Regards, Alan

When the PC is soft-off, you should measure W, VA, PF
at the mains plug of the monitored PC.

Compare the measured VA, to the threshold value listed
for the power strip monitor. Some have a knob for adjusting
the sensitivity, meaning the threshold is variable.

Paul

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XPost: alt.os.linux.mint

On Sat, 12/28/2024 4:29 PM, pinnerite wrote:

I would but I would have to be a contortionist.

Alan

This is why my equipment is on tables.

None of the PCs are on the floor.

I store my "dust bunnies" at floor level.

But this also means, I have to lift the
latest PC pretty high, to put it on its perch.
The drive bays in the new PC, end up at roughly
the same height as my head.

+-------+
|Phantek|
|Enthoo |
|Pro |
+-------+
================= Top Table for PC case
XX XX
XX mmmmmmmXXmmmmmmm Monitor is on first table
XX m XX m and sits behind a table leg.
XX m XX m
XX m XX m
XX mmmmmmmXXmmmmmmm
============================ Bottom Table
XX XX
XX XX
XX XX
XX XX
XX XX
XX (Dust Bunnies) XX

Paul

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