cheap thing bought at dollar store, at home used used a wallwart 12vdc with a cig lighter style attach, worked fine for year, then i accidentally mana ged to short the 5vdc output during a quick kludge on a project. now this c heap little thing started putting out 7.6 vdc rather than 5vdc, unbeknownst to me. long story short, i then used it to try charge one of those 'recha rge your cell phone' portable batterys. and it toasted it, no more blue li ght showing charge or redlight showing it is charging. of course, it would , wrong input voltage! dumb eh? i figured there would be some sort of minim al input protection on the battery thing, boy was i wrong. take this littl e cheap thing apart, inside is a fuse to protect (whatever?) itself from ov er load, a resistor, a small millihenry inductor and a 6 pin chip that doe s 'all the work'. (oh and a red l.e.d. to show the output is on). nothing looks remotely cooked or smelled like usual toasted electronics, must be al l internally fused or opened? amazing how cheap it was built, gotta give th em chinese credit, they know how to slap these things out by the millions a nd never give a dang about failure modes or protecting dumb end users! ;-))
best way to 'repair' these cheap little things is to go to the dollar store and get another one.