I recently bought an APC Backup UPS Pro 650 for my Pentium III 600, with
2 20 gig internal IDE hard drives, a CD-RW drive, 256 megs of RAM and an
internal 56Kbps V.90 PCI modem. I am running RedHat 6.2 and APC's
powerchuteplus-4_5_2-1_i386.rpm with a special cable provided by APC to
run between the UPS and my Linux box. I did a self-test of the unit with
the Powerchute Plus software and it passed. Then the next night, our
area was beseiged by lightning storms and the electricity went off for
just a minute. My computer was off at the time, but plugged into the
UPS, which was on and now emitting a continuous beep with its red light
on indicating voltage overload.
The plot thickens. I did some brutal testing to try and see if the UPS
software will perform a graceful shutdown when the UPS is unplugged from
the wall. Basically, I ran "sync", then unplugged the UPS. The UPS went
right into voltage overload, even though the computer manufacturer says
my PC runs under 420 watts of power, which is the UPS can handle. This
is a hard test because when the UPS doesn't go to battery, it's likely
unplugged the PC from the wall and the machine does not shutdown
gracefully and has to run fsck the next time it boots up. Nonetheless, I
tried it again and this time it went into backup battery mode.
Intermittent problem? No. After pondering this for a while, I realized
the internal modem was NOT online this time!
Suspecting that perhaps there was a conflict between the modem and the
cable running from thte UPS to the serial port, I disconnected the cable
from both sources and tried my brutal test again with the modem online.
What do you think happened? The UPS kicked into voltage overload right
away. So I am *presuming* that this is not a software issue.
Perplexed, I replaced the APC UPS with a BestPower Patriot Pro II 750
(470 watts) without any cabling between the UPS and the machine and no
CheckUPS software installed (that's BestPower's unattended shutdown
software). I logged onto the Internet with my modem and plugged the plug
from the wall. The Best Power UPS went into battery mode and kept the
machines running.
So then I took my APC UPS and hooked up an old Pentium 200 with 32 megs
of RAM, an internal CD player, an external HP SureStore 2000 tape drive
and an external 28.8 modem and made sure everything was running, but did
not install the Powerchute Plus software or hook up the cable between
the unit and the machine. I pulled the plug and the UPS went right to
battery mode and the machines kept running.
Has anyone experienced a similar problem? What does it sound like to
you? What would have caused the UPS initially to go into voltage
overload right after the electricity went off and nothing hooked into
the unit was powered up? Is it possible that the modem shorted out or
something and is taking too much power now? Can a modem get that out of
control? I have asked around and never heard of this? What kind of
advice do you have for me to track down this problem further?
Any help appreciated.
Gary
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