I have had a couple of adjustable ac/dc universal voltage switching power supplies die on me. I need the adjustable part to force charge lithium tool batteries that their charger won't accept.
The last one that died was charging a 18v Ryobi battery. I forced the power supply case open and with a eye lope found the blown part. I had to search Yandex in Russian to find the part. AliExpress is apparently the only one that sells them. It's a smd pwm CR6850P23 6 pins. From the image search it looks like on mine the gate is blown open. One of the spec sheets said a small resistor in line with the gate is "required" to protect it from switching spikes. I haven't looked yet to see if there is one. I was kind of hoping to just hot wire around it, but that won't work.
The whole 3-36v power supply is only about $18. Replacing an smd chip for a couple of dollars isn't worth the effort. I haven't seen any inexpensive adjusable dc supplies I can hot charge with, so I ordered a 0-24v supply as a replacement. Almost all the bad tool batteries I deal with are fully charged at 20-21v
