This was originally posted on APC forums on 5/2/2010
I purchased a Back-UPS XS 900 a couple of years ago and this problem began shortly after purchasing it but I haven't had the need to solve it until now. When I connect my workstation to the UPS, it seems to work and charge fine.
When I print on a printer connected plugged into another outlet on the same circuit (but not connected to the UPS), the "On Line" and "On Batter" lights start blinking alternately at about 2 second intervals and I can hear a clicking like a relay switching each time. This is the problem I had when I put the UPS in storage.
When I connected it this morning, it seemed to work fine until I printed. I do not know how it got into a working state while in storage but now that it does not work, I do not know how to fix it. I printed once, the UPS started clicking with the lights alternating and there is no remedy.
I only have two devices connected to it -- a work station and a monitor.
* APC Back-UPS XS 900 model BX900R serial number JB07222001459
* Dell Inspiron 590
* HP Laserjet 2300D on same circuit but not connected to UPS
I also have some other equipment connected to the same circuit but not plugged into the UPS -- 1 server, 1 small switch, and 1 DSL modem.