Mine had 2 R068 sense resistors and I blew several XM-L2’s at Turbo. Worked fine in the lower modes but Turbo turned it Off. Poof!
I looked to the star, the thermal path on mine was a bit low so I used solder paste to fill it and got an XM-L2 working at 7.15A. But I coudn’t get it to throw like the current indicated it should. So I tried to put a different resistor on it. Poof! I mean as soon as Turbo is selected it simply goes off, then the emitter is dead.
So I did the math on the sense resistors. Stock the resistance is .034 or thereabouts (not at my desk) So I pulled one of the R068 and stacked 2 R200 there for .040 total. This got me 4.83A at the emitter and all was well. Only I was getting lower output of course. And I didn’t get this TK61 to do 150Kcd. So I did some more math and decided to use an R140 in place of one R200 for some .037 total resistance. Poof!
Getting realllllly tired of poof!
So I pulled the star, put a copper Comex star with a Luminus SST-50 on it. The 20mm star is too small of course, so I cut a disc of copper at a similar thickness and put it under the Comex, my new disc is maybe 30mm. Just fits between the lead holes. Then I stacked a second R140 on top of the R200/R140 stack. So now my total resistance should be less, at around .027 or so. The Luminus is getting 5.60A measured between the pack and the driver. (The 7A reading was actual emitter amperage, taken from a loop soldered into the neg lead with my clamp meter)
It works, works pretty well actually, and is doing 162Kcd or so (again, I don’t have actual numbers here as I’m on a different computer and not at my desk with all my notes) But pulling the dome off the SST-50 didn’t net the throw gains normally associated with the Cree emitters.
I have one of the new Noctigon 35mm copper stars on the way. I plan to try a de-domed XP-L here and see where that goes. I need to get new sense resistors as I don’t trust the R068 I pulled off. Might just get the next step up from that as well in an effort to lower amperage a bit.
FWIW, I used a Qlite board that was totally stripped…put a new ATiny13A with Star firmware on it, used the resistors as usual but no regulators. I did a Zener mod so that the ATiny13A can get power directly through the board. If you’ll notice the via with a pad in the lower right hand quadrant, beside a cap, above the 151 resistor, that’s where I got power for the ATiny13A.
I used it a fair amount at 7.15A, the 5 modes worked well, low was quite low (no notes here) but I couldn’t get focus where I wanted it and the best throw I got was just over 500Kcd (yeah yeah, my memory sucks…might have been 555Kcd but not sure) So yeah, I screwed it up but plan on making it rock again.