i have an APC brand UPS installed inside another project, and have just recently powered it up for long durations for the first time. and i've picked up an annoying buzz in a small transformer on the main circuit board :<
i'm certain this little jerk is the only thing buzzing, but i've failed to find it online for R&R.
the text reads : 430-0271-Z. VIKING F-1. LEI-4 BJ08.
the buzzing is present intermittantly when the mains power is connected, and transitions to a steady sound when battery is unplugged. it goes away completely when battery is plugged in and mains is disconnected, so i conclude it's part of the charging circuit.
could a faulty battery cause this problem?
if it's a custom part for APC, and i can't source a replacement, is it safe to muffle the buzzing with some self-adhesive duct foam? i mean the black mat material used to insulate commercial air conditioning ductwork. it's a dense heat-resistant rubber foam.