Back-UPA ES 750 clicking under low load

[Anonymous user]

I have a Back-UPS ES 750. Recently it has started clicking on and off every 10 seconds or so under certain conditions. It only seems to happen when the computer has switched off the display because it has been idle. If I do something on the computer to make the display come back on, the clicking stops. If I put the computer to sleep, the clicking stops.

I have PowerChute 2.2 and on the Performance page, it shows no unit switches at all, and when I look at the voltage on the Current Status page it doesn't vary more than from 119 to 121 volts. I have set the sensitivity to Low, but that didn't seem to really help. The Self-Test passed.

Any ideas what's going on?

[Erasmus_apc]

Do you have an exact model and serial # on the UPS? This would be on a white barcode on the bottom/side of the unit.

When your computer shuts off your display, does this coincide with the computer going into standby or hibernate? Also, is there any daisy chaining of power connections to the load (surge protector, etc.). Any printers plugged into the UPS?

[Anonymous user · Accepted solution]

Thanks for the reply.

The model # is BE750G. Serial #: 4B0751P40002

It's not when it goes into standby or hibernate, just when the windows power settings kick in to shut off the display when the computer is idle. No daisy chain. I have a laptop with a docking station and a monitor plugged directly into the UPS, which is plugged into the wall outlet. I also have a phone, router, and cable modem plugged into the UPS, but no printer.

[Erasmus_apc]

Has the site wiring fault LED been on at any time on the UPS? What if you turn the monitor off manually instead of let Windows turn it off?

Have/can you try a different outlet?

[Anonymous user · Accepted solution]

Thanks a lot for your help. If leaving the master feature off fixes it I will probably just leave it at that, at least for now, since I wasn't using that feature anyway.

[Anonymous user]

I have not seen the wiring fault light come on. I have tried turning off the monitor manually to see if it would happen, but it didn't.

In fact, it doesn't happen all the time. It didn't happen at all yesterday (of course) though it was happening every day for a while before yesterday. It definitely only happens when the computer has been idle for a while, and I can definitely stop it from happening by waking the computer up or shutting it down.

Unfortunately, trying a different outlet would involve rearranging my office.

It just occurred to me that I turned off the "Master Enable" setting on the UPS yesterday. Could it be the master switch that is clicking on and off? My computer is a laptop with a docking station, and maybe when its display is off it falls below some threshold of power consumption that causes the master switch to cycle on and off. Or the laptop could be cycling between charging and not charging, which could be causing the master switch to cycle on and off. That must be what's going on.

[Erasmus_apc]

If you turned off the master outlet feature on the UPS yesterday, and it hasn't happened at all today (assuming that is correct), then yes that is rather telling. It's likely the current threshold that the unit is set at for controlling the outlets is being hit, and then clearing, and the relay is making the noise when this happens.

Use this link to see the manual for the unit, which includes how to change the threshold. See if changing the threshold allows the unit to work with the master outlet feature on. Otherwise you may need to keep it off:

[http://www.apcmedia.com/salestools/KBOK-766PMZ_R2_EN.pdf]