I had a small UPS that I put in place to backup my wireless modem. A couple of weeks ago it died with the overload light turned on. I just bought a battery for this thing, so it was worth opening up for a look.
On the battery charging circuit two things were immediately obvious: a large electrolytic was leaking and the switching power IC had blown itself to pieces. Fortunately, it had blown the entire top of the IC so the number was still visible. Unfortunately it was a TNY255g which is listed as obsolete by Mouser and Digikey. The only source I could find was through ebay either in China or Hong Kong. After looking through the listings and reviews, I picked some from a vendor called Chipsgate. Six for USD $4.70 + 3 s/h seemed worth a risk. I figured on a 40% chance that I would get something that worked. However, the vendor offered a 60 day warranty and they seemed professional, so what the heck.
They showed up the other day, I installed a chip and replacement cap and now I have a working UPS.
It's only one data point, but I would try Chipsgate again if the need arose. Anyone else have experience with them?