Fenton BS-1700 UPS - bad AC input relay X-cap
On a Fenton BS-1700 UPS, it has the problem of not always starting up (often, with a relay chattering) when AC is applied to the mains input.
So I tried checking the X-class series capacitor (which acts as a reactive component for current limiting for the AC input relay which closes when AC is applied to the mains input - it is not controlled by any other circuitry) and upon measuring, it was less than half of its rated 0.33uF capacity, and replacing this component fixed this problem.
The X-class capacitor at fault was a Carli unit - I've seen X-class capacitors lose significant capacitance in some cases over time during use.
A good tip from me is to check any X-class capacitors which are being used as current limiting capacitors as I mentioned earlier.
So I tried checking the X-class series capacitor (which acts as a reactive component for current limiting for the AC input relay which closes when AC is applied to the mains input - it is not controlled by any other circuitry) and upon measuring, it was less than half of its rated 0.33uF capacity, and replacing this component fixed this problem.
The X-class capacitor at fault was a Carli unit - I've seen X-class capacitors lose significant capacitance in some cases over time during use.
A good tip from me is to check any X-class capacitors which are being used as current limiting capacitors as I mentioned earlier.
