Top MCU upside down: Appears to say "A10"
Mine had 2 R068 sense resistors and I blew several XM-L2ās 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 coudnāt 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 didnāt 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 donāt have actual numbers here as Iām on a different computer and not at my desk with all my notes) But pulling the dome off the SST-50 didnāt 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 donāt 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 strippedā¦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 youāll notice the via with a pad in the lower right hand quadrant, beside a cap, above the 151 resistor, thatās 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 couldnāt get focus where I wanted it and the best throw I got was just over 500Kcd (yeah yeah, my memory sucksā¦might have been 555Kcd but not sure) So yeah, I screwed it up but plan on making it rock again. 
What cell configuration are you using Dale? Sounds like you may be feeding too much power to the Attiny and then it's transmitting too much voltage in the PWM signal to the HX-1175.
Where are you connecting the PWM into on the board? The same spot you spoke of in Post 70 above?
EDIT:
I recommend you power the attiny from the pad with an "X" below. The pad between the MCU and the yellow component labeled "226A, 90HF1". I don't know if you need to take off the zener mod.
When I make any changes at all I put the light completely back together to test it, save for leaving the reflector out in order to clamp the meter on the wire loop at the emitter (most of the time)
So the power supply is the battery carrier in the TK61. I have 4 Panasonic NCR18650B 3400mAh cells in it. Iāve also got the extension tube with 4 more but donāt use that when testing.
And yes, I connected pwm at the MCU side of the 30,000 resistor, just off the pwm leg of the mcu (mcu removed of course) so Iām bringing the pwm back in where it was originally coming fromā¦the signal then goes through the 2 resistors on the way to the controller just as it was originally set up.
With the Zener mod to the Qlite board, the MCU cannot get over 4.5V. Works on a dozen or more drivers Iāve built for MT-G2ās so it should work here, right?
Hopefully, someone that knows a lot more than me can help you. I'm wondering if the zener is not adequately bringing down the voltage to the Attiny.
buying an SBT-70 and putting it in this TK61, letting the power fly. 
Ultimate throw be damned (Iāve already got 617Kcd in another light)
attiny13 just stops working if voltage goes over 6v. Besides, whatever component is getting the PWM signal operates from a digital signal (either on, or off) so more voltage or less voltage on the PWM pin should have no effect on the output. 6 volts is just as 'on' as 4 volts.
I donāt think this is the case. Comfyās explanation is correct, a higher voltage on the buck controllerās PWM input will not cause the problem DBCstm described.
Itās more likely that the driver produces high voltage spikes at higher currents. We have that problem with other drivers as well. The ābigā LEDs seem to cope with this better than the XM-L/L2.
I did think that the hx-1175b was shown to work OK driving an XM- series LED at higher currents than that thoughā¦ Am I remembering wrong?
I thought some buck controllers do relative voltage adjustment.
Are you two talking generalities, or about this specific buck controller? If generalities, do you feel 100% certain that it's safe to rule out the PWM voltage as the potential issue?
āgeneralitiesā puts a negative spin on what we are saying. We are telling you how all PWM inputs work.
The only thing a PWM signal communicates is āhighā or ālowā (two states, like zero and one).
Not trying to cast dispersions on what you 2 are saying. Just trying to figure out what we know for certain in order to figure out how to help Dale.
The driver seems stable, but I have not used an oscilloscope or anything to search for spikes. Given no other options at the moment, I think Dale should grab the voltage from the point I recommend he use in Post 82 and see what happens.
Donāt worry, no offense taken. I just wanted to be plenty clear that we arenāt speculating about the PWM. PWM signals work (provide a duty cycle) or donāt work, but there is no device that gleans something additional from the voltage on a PWM input.
Can you remind us of how far this driver has been successfully pushed with an XM-L?
I haven't tried to keep track of that. I know some people have used it to drive xml's using it in it's stock configuration (7ish amps). It's a popular UF-T90 mod. Driving an xml/xml2 over 7 amps is touchy business with any driver. I did a quick search and saw a couple examples of driving xml's in other lights or just testing of 7 amps and less.:
Interesting. Thanks for the links, thatās the kind of thing I needed. So, while Iām confident about the PWM voltage not being the source of the problemā¦ maybe it would have been better if DBCstm could have tested the stock driver on an XM-L/L2 before doing the ATtiny13A mod. My money is on the idea that he just got a bum driver!
I got 2 and have had the same issue with both. The issue is in the driver giving too much Voltage to the emitter and frying it when using larger wires. Richard has been having the same issue Iāve had and is working on solving it. Heās burned up 10 LEDās to my 5 or 6. So now I know itās not just me.
So, apparently putting 20 ga wires on it lets the buck converter run the Voltage up too high.
So youāre saying that with the stock wires it doesnāt zap XM-Lās, just once you bump to a heavier wire gauge? (just verifying!)
That's right. I had one driver that I got away with the thick wires on...The subsequent ones have been blowing LEDs.
Bummer. Starting to sound like this is an MT-G2 emitter only driver. Thank you for the info guys. I was just about to build a light with this driver and xml2's. Need to go another route, it seems.
I will post some more details soon, but all it needs preliminarily is a little output capacitance. 22uF ceramic is enough to keep it from blowing LEDs with the factory sense resistors.
I also tried swapping FETs, diodes, and adding more inductance, none of which seemed to help at all. I was surprised that adding more inductance didn't work.
I will see how far I can push it with extra capacitance. Unfortunately I don't have an oscilloscope so I can only tell whether or not the voltage is staying within the limits of an XM-L2 but I suppose for our purposes we don't need a perfectly clean output. 
Good work RMM. It seems that an inexpensive scope might pay dividends if you are burning up a lot of LEDs in your testing? Just FYI, the PC based one comfychair is using is $75 shipped from the US.
I do have a scope, although I only get one channel. It seems that my QX5241 driver zapps LEDs at 6A, based on one potentially flawed test. Iāll get some more caps in hand and take a look at that on the scope ASAPā¦ starting at 4A of course ;-).