Fixing a faulty UPS

Jiggy

Well-Known Member
Joined
Jun 24, 2011
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Capetown
hi Guys

i have a UPS that i would like to fix, im a hands on type of guy and i just need someone with electronic experience to guide me.

i have a Mecer 1000VAc UPS, i

when disconnected from 220v and running on battery backup - outputs 220V - no issue
when connected to 220v and switched off , it charges batteries - no issue
when connected to 220v and switched on - it charges batteries but no bypass/ups function - it trips.

Error is " Bus Under voltage" code 03. thumb sucking i am assuming the incoming power got whacked so im looking for a capacitor/ resistor that need to be replaced.

i'm going to strip the unit this weekend, hopefully someone can point me in the direction on where to look.
 
Have you checked the condition of the batteries first?
yes i bought two brand new batteries, the problem is with incoming side. as soon as power is restored the unit trips and it does not bypass power. this may have something to do with the relays not switching... or something causing them not to switch, i should be able to bypass the ups - which its not doing.
 
Simple question but u made sure that the switch that actually turns it on is functioning? I guess u did if it's working while not on mains. I would agree it sounds like it's between the mains supply and the circuit that bypasses the inverter
 
Simple question but u made sure that the switch that actually turns it on is functioning? I guess u did if it's working while not on mains. I would agree it sounds like it's between the mains supply and the circuit that bypasses the inverter
yes, as i can switch on and off. connecting to the pc and reading it through the software manager i was able to pick up the Bus under fault.
 
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