Mist wrote:
> Windows XP SP2
>
> Picked up the remote control, turned on the TV, computer shut down totally
> dumping a screen full of spreadsheets. Gotta love that.
>
> Previously, the monitor has just flickered and reset itself.
>
> It is sporadic. I haven't been able to discern a specific item that I'm
> doing when it happens.
>
> I had thought that it might be the scanner so removed it. Obviously it
> wasn't.
>
> I've asked the IT folk at work, electrician, my computer guru - all are
> lost.
>
> HALP! (an upgraded "help").
>
> Suggestions, thoughts, updated Ouija boards....
>
> Mist
>
If you're thinking of using a UPS, it depends on which kind of UPS,
as to whether it would make a difference.
The computer ATX power supply, has something called "holdup time".
If I were to look at specs on Newegg, I might note a "17ms holdup time"
for a supply.
http://www.newegg.com/Product/Produc...82E16817104999
The power supply has a large capacitor, that stores energy in it.
The AC from the power cord, is converted directly to DC, and
stored in the capacitor. The switching conversion in the ATX supply
feeds off that capacitor.
A cheap UPS is the SPS or "standby" type. With the SPS type, it takes
some number of milliseconds, to detect a problem with the AC. If the
AC completely disappears, it takes the UPS maybe 8 milliseconds
to respond. So for 8 milliseconds, the UPS has zero volts on its
output.
The 8 milliseconds number if less than the 17 millisecond number.
And that means, the ATX supply has enough energy stored inside,
to "hold up" until the UPS starts running off its battery. In the
following diagram, maybe you can see that if the outage lasted
longer than 17ms, the ATX internal DC voltage would drop below
the level at which the thing could work.
0 8ms
---------- +------------- ATX internal DC (primary) voltage
\ | (No glitch is seen on the ATX outputs,
\ | as long as the level is maintained.)
\|
--- (Level at which it stops working)
--- Zero volts
So for correct operation, the UPS is relying on that property of
the ATX supply, to ensure proper operation. The ATX holdup time
must be longer than the UPS response time.
If, for any reason, the ATX supply cannot store enough energy,
it could "tip over" and the computer could reset.
The UPS will give you relief from this problem, as long as
the ATX supply in the computer is working properly. It could also
be that there is a problem with the ATX supply. Or even a problem
with the A.C. wiring. The fact that your monitor "resets", suggests
the power supply on it is seeing an extended power outage as well.
If the ATX supply had no hold up time at all, this kind of UPS
would work. This is a "double conversion" type, with
"zero transfer time". The fact that the unit is fan cooled,
tells you it does AC-DC-AC conversion all the time, and
no matter how the AC glitches on the input, the thing is always
feeding off the battery, and the battery voltage remains
smooth. It would take seriously defective AC wiring, to
upset one of these. Whereas a cheap SPS type of UPS, one with
a finite response time, is quite efficient, and doesn't waste
power, the double conversion time does waste power and there is
heat output all the time. Even when the AC is working, these
still dump out heat. As a reviewer notes in the review for this
item, there is a fan and it can be noisy.
http://www.newegg.com/Product/Produc...98&Tpk=SU750XL
This is the same idea, only with a little more "beef" to it.
http://www.newegg.com/Product/Produc...8&Tpk=su1500xl
The UPS wiring looks like this. You use the outlets on the UPS
that are marked as being powered by the battery. Some outlets on
a UPS, may only be "surge protected", and don't actually run
from battery during a power outage. I use a chain of a couple
power strips, to get enough outlets for all computer items.
(Many small wall warts etc, take up most of the space.)
AC_outlet ---------- UPS ------------ Computer
------------ Monitor
------------ Cable Modem etc.
Maybe you could borrow a cheap UPS from someone, and do a little
testing. If things improve, then you could go shopping for one.
HTH,
Paul
Linear Mode
