On Feb 17, 1:05*pm, "A. Baum" wrote:
On Thu, 17 Feb 2011 08:50:59 -0500, Art Todesco wrote:
I have a computer and DSL modem tied to an old UPS (with new batteries)..
*When I have a power failure, the computer keeps right on ticking, but I
always have to restart the DSL modem. *I've even restarted the modem
while running on the UPS and after its restart, all was fine. *I am
assuming here that the switch over time is killing the modem. *I looked
at the modem and its walwart. *It says 12 VDC. *I was wondering if
putting a few thousand micro farad cap across the 12 volt line might
help. *Anyone have any experience with something like this?

I'd try a 1.5 farad cap used on auto power amps. Usually can pick one up
for 10+ bucks. That should buffer the source more than enough and would
be much cheaper than a new UPS. *

Seriously, We don't even know the voltage of the supply except its
suppose to be 12 at rated current
output. Its easy to fry something. Unregulated outputs go up over 16
volts.

As I said, pulling the plug on the UPS will narrow down the problem
better.
I'm worrying some other telephone line problem can occur during a
power
failure, up setting the modem. Many devices also warn of reconnecting
a wall-wart supply while still active.