[ale] A UPS is giving me trouble.

Transam bob at verysecurelinux.com
Tue May 27 21:07:29 EDT 2003


On Tue, May 27, 2003 at 02:59:15PM +0000, Cory T. Echols wrote:
> I have a Tripp Lite UPS unit attached to my debian box.  On it is a
> sticker with a very stern warning that connecting the serial cable from
> the unit to the PC may cause damage unless the software is properly
> installed.  How could the unit get damaged by this?

The only possible way would be file system corruption due to an abrupt
termination of AC power.

The RS232 (serial) specification states clearly that no RS232 device shall
be damaged by any wire being either open or shorted to any other wire or
to ground.

> Also, this unit is giving me a bit of trouble.  The UPS will cut power
> to the PC at random times when there's no perceivable power
> interruption.  I'm trying to decide between a new unit and a battery
> replacement.  Is there a reliable way to be sure the battery is the
> problem?  The windows-based monitoring software wasn't helpful, and
> there's no diagnostic info in the manual.

The first question is whether the battery is no good.  To check, shut your
system down until it is at the Boot PROM level (or boot it and hit DEL to
get it there).  The reason for this is that there will be no active disk
file system.

Then, the rocket science:  unplug the UPS from the wall and time.  If the
UPS keeps the system running for X minutes then the battery is at least this
good.

If the UPS will drop power for brief blackouts shorter than this time then
the UPS's electronics are broken.

For battery replacement (including free installation), go to Batteries Plus.
They have stores on Hwy 41 and on Pleasant Hill (near Red Lobster).

New UPSs are so cheap that it makes sense to just buy a new one.  I've
had excellent experience with many APC ones and highly recommend them.
I've heard good things about TrippLite.  Don't buy an off brand UPS or
surge protector.

> Thanks!

> -- 
> Cory T. Echols
> ctechols at mindspring.com

You're welcome!

Bob Toxen
bob at verysecurelinux.com               [Please use for email to me]
http://www.verysecurelinux.com        [Network&Linux/Unix security consulting]
http://www.realworldlinuxsecurity.com [My book:"Real World Linux Security 2/e"]
Quality Linux & UNIX security and SysAdmin & software consulting since 1990.

"Microsoft: Unsafe at any clock speed!"
   -- Bob Toxen 10/03/2002
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