My light has a problem and it would seem that .
Finally got around to putting together my Mag623 tonight. Pretty standard recipe: 3D host, Osram 64623, AW soft start 3-level driver, 4x AW IMR26500 w/ PVC sleeve, stock tailcap spring trimmed, bent and sunk into bottom of tailcap (I machined a small flat groove at the mating surface to ensure a very solid contact).
Popped in the IMR's fresh off the Pila (4.19-4.20V), took her outside and hit the button. It worked magnificently, absolutely stunning. Left it on low for about 30 sec, then on mid for another 20s or so, then to high. After maybe 20 seconds on high*, the light cut off completely and suddenly. I immediately pulled the batteries and let it cool off.
Put in another bulb (latex gloves worn at all times during bulb handling), and tried again. No go. Tested both bulbs and a third NIB bulb, and all had ~0.4Ω between the pins. So it seems they didn't
Loosened and re-tightened the driver/switch set screw several times and really torqued it down to make sure of good contact. Measured resistance between host body and switch body and got ~0.1Ω ... put everything back and tried again, nothing.
Pulled the batteries and found two at 4.09V and two at 4.10V.
Tested continuity between tailcap/spring assembly ... same as before first assembly at ~0.3Ω.
Put everything back together except the bulb and head/reflector. Turned switch on and measured voltage between pin receptacles -- nothing, 0.0V.
So I did a few tests involving the switch. I don't really understand the workings of the driver, so these were pretty much random tests. With the switch alone and out of the body, I measured resistance between the "+" batt contact point and aluminum switch "body".... infinite. Then I measure voltage between those points and found about 50mV. Just measured this again (about an hour later) and found 42mV. Maybe some sort of slow discharging capacitor in there? Or is my cr@ppy Craftsman DMM being screwy? --right now all my good meters are in my lab at work.
Finally, I put the switch and batteries back in and measure voltage between the negative of the bottom battery and the switch body. And to my surprise, I find the full battery voltage of ~15.6V. Likewise 15.6V between batt "-" and host body. That seems like a short through the switch => current would not flow through the bulb. Yet there is no continuity through the switch when tested alone, as mentioned above.
Can anyone figure out where I've messed up here? Sorry for the lengthy post, just trying to give you all the info I can think of.