rc40 fenix bright flashlight bizzare repair

[coppercone2]

So I did a repair job on my rc40 flashlight by replacing a burned out LED. It was alot of work, I had to use a hot plate to solder it and apply thermal paste and undo loctite threads and all sorts of non servicable crap.

When I turn it on, the replacement LEDs do not work, it has 3 pairs of wires going to 6 LEDs. When I try the LED with a power supply after desoldering the wires, they work fine.

I also noticed this oddity, when you turn the flashlight on strobe mode, then turn it back into constantl mode, the set of lights that did not work, work, and a different pair of LEDs stop working.

I took it apart a long time ago and the circuit is all built in a little cylinder with vertical PCB's and its a bastard to trouble shoot.

Can any people that know about these sorts of flashlights give me a clue as to how it might be wired and what the hell is going on that it alternates between LED pairs. They give full brightness, just one randomly chosen section does not work. Clearly the power supply works, and when it blinks, all LED's blink, but a set of 2 in 2 possible positions wont turn on when on constant mode.

When I measure the voltage on the pair it decides not to turn on, it measures a low voltage. But the supply cant be broke since it sometimes does decide to turn the ones that dont turn on on, but turn off another one. Like a faulty load switch controller? So all the signal paths have power capability, just one of them does not turn on like it should. But its not a blown transistor since sometimes it does turn on at full brightness so long another one turns off, when switching modes. And it stays on for a long time, so I know its not a PTC.

in short, its acting like a flip flop. how does a flip flop form after a failure.

[coppercone2]

well, the flashlight was sitting open on the bench for a few months and to my surprise when I tested it, it worked as I renemeber. However, when I reassembled it, the two high power LED no longer shine.


So clearly its some kind of mechanical issue. I bet its cracked solder joints from the battery spring and the weird construction of the circuit board (I-beam instead of wafer stack).