Back-UPS Pro 550 not switching on and emitting a constant buzzing noise when plugged in to mains

[BillP]

Hi, as the subject implies, my back-ups pro 550 does not switch on and when plugged in to mains emits the noise you can hear in the video I uploaded, this happes either with or without the battery. I checked the battery and it reads about 5V, on the PCB I could not see any damaged component, no leaking, no fried component. Does anybody knows what it could be that is causing this? What should I check with my multimeter?

Thanks

[Anonymous user]

That isn't right.

I believe the battery is a 12Volt unit.

I have no experience with this model but you may want to look and see if any of the capacitors are swollen or leaking.

[BillP · Accepted solution]

At first the usual sound is there when you turn it on but the screaming non stop . Yes, It happened as soon as I plug and switch on the unit and it will just stop.

[kkelso]

After many years of service, now I'm having this exact same experience. Replacing the battery does not resolve the problem. Short of replacing the unit, any ideas?