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Repairing a UPS backup power supply

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Active Member
Hi guys,

It's been a while. Before I actually buy a UPS backup supply, I need some advice and potentially save more than 50 dollars.

I found one from a friend (APC ES 500). Naturally, it was already dead.

I've hooked it up to the mains and no indicator LED or anything turned on. Dead as a dingbat.

I opened it up, and there was caking in the cathode terminal of the crimp area connected to the battery.

My question is: If the battery works well, would the whole thing light on? Because I had the impression that just by connecting it to the mains would at least give me some LED blink or flicker or something, since the battery would come into action if the supply wasn't there, isn't it? Or it is more than just the battery?



Well-Known Member
Most Helpful Member
The APC User Manual should be a good start. My suggestion is look for the obvious such as burned fuses or other protective components. The short manual should give you some ideas as to troubleshooting. My experience has always been it is easier to replace the units than repair them unless the problem is obvious.



New Member
Hi Vizier

A lot of APC units will be dead if the batteries are dead, they require power from the batteries to turn on. Try a new set of batteries.
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