that is the kingpan charger and the choke is what is overheating. it is carrying a lot of current and that causes it to overheat.
i just blew up my charger by reversing the battery cell on the charger output.
it is a 10A single cell charger that puts out 3.65V so i was using it to charge up a pile of loose cells i have that i am using to build a 72V12Ah ping pack from. i thought i was so careful, looked right at it and said "that is the positive tab, that is the negative tab" and then put the alligator clips on the wrong terminals of my charger. so i had the battery cell backwards on the charger but the charger was not turned on yet. so i was connecting some more cells together to put on the charger with that group of cells, and i hear a pop and see some smoke coming from the charger. i had blown the schottky diode on the output. the diode is there to protect the charger from reversing the polarity. and protects the battery too. normally what happens is that the diode is forward biased when the battery is reversed polarity on the terminals. so the diode will conduct current and the current is so high that it blows open the fuse on the output. so the circuit is open now that the fuse has blown and charger is protected. that is why they have that fuse on the output. in my case the voltage was only 3.5V so the current was not enuff to blow the fuse and instead after a few seconds the diode overheated and blew. usually both would blow when polarity is reversed.
but i have some other schottky didoes i bot on ebay, SR5100 whcih are axial type schottky diodes, 5A100V. i think it was 20 cents, 10 for $2. so i had to take my single cell charger apart, unsolder the burned out diode, and solder the new one in place. at the same time i cut off that thyrister daughterboard and put a short solid wire jumper across the terminals where the wires from the daughterboard came down to the pcb.
it works again, wasted an hour or so, but it works again and i can finish charging all these pouches up.
if you have no voltage on the trace running from the schottky diode (that you loosened the clamp on) over to the choke, then there is something wrong closer to the front end of the charger.
if there is voltage on that trace, coming from the center pin of the diode, and there is no voltage on the back where the red wire is connected to the spot that has + on it. where the positive charger lead attaches to the pcb then the problem is in the back end.
if there is no voltage going from the schottky to that + output terminal then the choke has unsoldered itself from the solder on the trace on the pcb.
