That is a quick and easy fix of a very common problem of APC Back-UPS series.
The problem is that the UPS overload red light is constantly turned on even with no load at all. A google search did not reveal any solution other than the board is faulty and there is nothing you can do about it.
I was handed this UPS and naturally I employed all my google foo in order to save a seemingly fine UPS. This time however the solution didn’t come from google but from youtube. If you are like me then you are totally against the wave of video tutorials that are flooding our everyday life. I prefer a text with properly defined steps than a 15′ video documenting a series of three clicks in order to access the desired submenu.
However in electronics repair hackery it actually makes some sense to present your work in a youtube video. I doubt if it is faster this way but lots of people are actually posting very useful stuff there especially for obscure repairs such as this one.
I am writing the post because the solution is not in a youtube video but in a comment. If it was in the video or in the title then the solution will be findable by google. Instead the solution was in the comment section (yes I read youtube comments – can you imagine that?) in Spanish by Lujan Luis Giaccardi with the picture that shows the faulty capacitors red circled. Totally not findable. So I am posting it here for future reference.
The comment translated in google translate says:
If you turn on the red light of “overload” you have to change the two electrolytes marked in the photo this:
The youtube video where you can find the original comment is https://www.youtube.com/watch?v=66oKHjCo5AA
Since I am not much of an expert in soldering and removing surface mount (SM) electrolytic capacitors I found (easily this time) another youtube video to figure how to get rid of them. Here it is:
I changed the faulty capacitors with normal capacitors and lo and behold! It worked!
Hope that helps.