As Kony says there are several partial causes, any of which might
account for it alone, or one may be the whole problem. Thankfully
though there is a simple solution in many cases. First, if your pc is
on the same electrical circuit as the ac, move it to another one. Now
if necessary open the psu, discharge the mains reservoir cap, and
connect a 2nd much larger mains reservoir cap to it. This will carry
the psu through brownout for a very limited time. By very I mean a
fraction of a second, but that will generally be enough to get past the
initial surge of the ac compressor.
If you dont want to open the psu, you could use a separate unit that
rectifies the mains plus a big capacitor, and feed the pc off the
resulting dc.
There is a final time-honoured bodge if all else fails: an
autotransformer to add 10% to the Vsupply. Not recommended, not good
practice, but if you really get stuck it does work.
There are also several other approaches, all of which are not as easy
to implement, such as running the pc off a motor generator, using a
brownout detector to momentarily drop cpu freq right down, cut 12v
drive feeds and so on - dont go there, just waffling.
NT
None of these approaches is something suitable for DIY (do it
yourself) solutions.
First of all, the ATX PSU has rectifiers, an inrush limiter of
some sort, and the main caps. Adding capacitance arbitrarily to
the main capacitor, in an attempt to increase the holdup time,
means the rectifiers are going to get hammered harder when the
PSU is switched on at the back. Maybe this would cause a premature
failure of the inrush limiting solution, or blow the rectifiers,
with fiery results.
I happen to own a 30 year old central air conditioning system.
I find that in fact, my sump pump motor causes a larger flicker
of the lights, than the air conditioner. The air conditioner
uses an interrupter (relay) to switch the power on to the two
motors inside the air conditioner. Then there is a third motor
in the furnace for air circulation. I believe at least two
of those motors are impedance protected, and that leaves the
compressor as the "ugly load".
I'm not sure what kind of motor is in my sump pump. It doesn't
have an external capacitor for starting, and almost reminds
me of an induction motor. But, in any case, the sump pump motor
makes the lights flicker more than the AC does.
And with these loads, I have never had even the slightest hint
of a problem with computers. And I've had a pile of computers
in the house.
That is why I say, the electrical system should be checked
for problems. Sure, it could be a distribution problem within
the house (too small a panel, amateur wiring job etc). Or
it could be a pole transformer problem.
What I'm trying to explain, is a home owner should not be
using a Line-R to fix a problem which is normally handled
adequately by modern computer design. Something is wrong
with the power, and finding the cause is more worthwhile
than placing "bandaids" on every appliance that is having
problems.
The autotransformers I've seen, are unregulated devices.
That means, if you dialed the knob on the autotransformer
to get exactly the right voltage to the load, the instant
the input line voltage changes, the autotransformer will
pass the bonus on to the load. Since the autotransformer
has no regulation, it is not a solution for a sag problem,
if the input voltage changes with time. A device like the
Line-R is closer to being correct for the job, as at least
it attempts to take a wide range input and create a stable
output voltage. But if the Line-R is also dropping the
ball, then the input power is simply too "dirty" to be fixed.
Getting the electrical panel or the pole transformer fixed,
will cost a whole lot less in the long run.
Paul
