APC UPS backup clicking noise

[Philpc]

I have a XS900 that was lying around and had not used for a couple of years. I just bought new batteries and the thing operates;however after awhile it made the same aggravating clicking noise that irritated me in the past. Per info on the APC website I adjusted the settings to reduce the sensitivity and still no change.
From what I've read this can be fairly common on some APC ups's;I haven't found the issue to be present on other brands.
Is there some electronic component that might be shot that I could replace?
I hate to just toss it out
thanks

[budm]

Re: APC UPS backup clicking noise

It sounds like it has AVR (Automatic Voltage Regulator) using relays to switch the tap on the transformer to maintain the AC output due to variation in the AC input voltage so the relays are switching and trying to maintain the output to within 12% per spec.

[Philpc]

Re: APC UPS backup clicking noise

thanks for the reply. I wasn't aware of the ability to manually change the sensitivity;I had been doing it via the power chute software. Anyway I attempted it per the manual instructions you posted and still no change.

I'm guessing it's just shot but thought it might be a component like a capacitor I could replace. I did open the case and saw no obvious damage like burned components or bulging capacitors.
Anything else I could consider before trashing it?

[budm]

Re: APC UPS backup clicking noise

You should monitor your AC line voltage feeding it to see if it's steady at 120VAC or if it is going up and down, if it is going up and down then it will try to regulate the output voltage by switching the tap switching relays.

[Philpc]

Re: APC UPS backup clicking noise

OK Measured voltage couple of times;meter showed 117 volts one time and 120 another. When I had the UPS connected to the computer with its software loaded it indicated the voltage at 117 volts

I would think if it was the voltage difference itself it would have done it when the unit wasn't as old; the clicking is like a rapid fire type;it's not an occasional noise .After I posted this question I found the following post on the APC site that has me thinking maybe I should try replacing the capacitors

"I know this thread is already a couple of months old but I hope it helps someone. The clicking problem is a common one especially with an older UPS (more than 3 years old). Changing batteries and lowering the sensitivity settings are only a temporary fix if it even helps at all. The real problem is the surface mount electrolytic capacitors on their circuit board are notorious for going bad (electrically "leaky", lowered capacitance, and high ESR) which plagues many electronic products."

Any thoughts on that?
thanks again

[budm]

Re: APC UPS backup clicking noise

You can post the pictures of the board, you will also need cap meter that can show capacitance and ESR or you can try changing the caps.

[Philpc]

Re: APC UPS backup clicking noise

Will go ahead and replace the caps.Any advice on brands?

thanks

[Krankshaft]

Re: APC UPS backup clicking noise

Get the datasheets for the current caps and compare their ESR and ripple to the datasheet of the caps you want to replace them with. I use Panasonic FC or FM for low ESR and Chemicon KMGs for general purpose.

I'm done with the BackUPS consumer grade series I've personally had that issue you described too many times on too many units. At one time I had 5 BackUPS units and all of them died within 4 years and yes it is switching the taps on the transformer for voltage trim purposes. I checked my line voltage when the first unit did this and there was no reason for it. It's probably an issue in the voltage measuring circuit which is telling the micro controller to go into voltage trim mode. Possibly a component has drifted and changed value.

I decided troubleshooting it wasn't worth my time and decided to get a better unit.

Ever since I upgraded to the SmartUPS series I haven't had any issues. Pure sine wave output, they're way more reliable, and they don't make my active PFC power supplies buzz like a nest of angry hornets like the BackUPS square wave inverters do.