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[JimC]

I thought some of you might find this interesting.

In my hobby room I have three computers. Two of the computers are running XP and the third is an old 486 running DOS.  To each of the XP computers is connected two monitors, one CRT and one LCD. The old 486 has a CRT type monitor connected to it. All of the monitors are plugged into a heavy-duty outlet strip, which in turn is plugged into a three-prong appliance module. I also have the power supplies for the speakers plugged into the same outlet strip.

The interesting thing is that when I turn on the two XP computers, somewhere in the boot cycle all of the monitors turn on. This is without me manually turning on the appliance module. This happens every time I turn on the two XP computers.

[Oldtimer]

The interesting thing is that when I turn on the two XP computers, somewhere in the boot cycle all of the monitors turn on. This is without me manually turning on the appliance module. This happens every time I turn on the two XP computers.

In other words the appliance module that controls the monitors and speaker power supplies turns on by itself during the boot process of the two XP computers.  Correct?

If so I'd connect a voltmeter to the power strip controlled by the appliance module to see if there is a switching transient on it just before the appliance module turns on. I believe some PCs have the ability to control the power in some monitors over the video connection or because of activity on it, but another poster will have to verify that. If so, again, that could be be source of the switching transient if you find one.

[JimC]

In other words the appliance module that controls the monitors and speaker power supplies turns on by itself during the boot process of the two XP computers.  Correct?

Guess I didn't state that very clearly but yes that is correct . Thank you for restating it.

I don't find the monitors turning on a  negative as I can't think of a time when I would turn the computers on and not want the monitors on.

[dave w]

oldtimer has probably nailed it. Something plugged into the outlet strip is fooling the "Local Control" on the appliance module into turning ON. A simple conformation is to plug a 100W light into the same outlet strip and boot-up. If the appliance module does not turn on this time, it is defiately the local control function being triggered by one of the monitors. Search the forum for "local sense" or "local control", it can be disabled by cutting a diode inside the appliance module. 

[TakeTheActive]

...The interesting thing is that when I turn on the two XP computers, somewhere in the boot cycle all of the monitors turn on. This is without me manually turning on the appliance module. This happens every time I turn on the two XP computers.

Since I'm willing to wager that, in our X10 "Old Geezers" Group,  I have the largest collection on 'antique' computers still in service, my money is on 'Local Control' and 'Energy Saver Monitors & Video Cards'.

Somewhere around 15-20 years ago (check with dave w - he *ALWAYS* 'corrects' me on my date estimates ), the manufacturers added circuitry in the Monitors & Video Cards to allow the Video Card to switch the Monitor from FULL POWER (power light is green) to STANDBY POWER (power light is yellow) to ALMOST OFF POWER (power light is blinking yellow). Either adding a 100 watt lightbulb (or a toaster over or space heater or...) to 'disable' Local Control *OR* temporarily disconnecting the video cable(s) from the XP computers before turning them on should fairly conclusively prove that "Energy Saving" is the reason...

...If so I'd connect a voltmeter to the power strip controlled by the appliance module to see if there is a switching transient on it just before the appliance module turns on. I believe some PCs have the ability to control the power in some monitors over the video connection or because of activity on it, but another poster will have to verify that. If so, again, that could be be source of the switching transient if you find one.

Yeppur.  I can probably come up with 'more formal' terms AFTER my first pot of coffee and when I head downstairs to the 'more current' computers...