NOTE: The mod will be documented in Post 6 below.
There seems to be no tear down info on this light. No doubt do to the unmovable cap that is at the switch-end of the light. I was certain it had thread lock. So I kept trying progressively higher levels of heat while using pieces of leather in a vice and in plier jaws. I tried to be gentle, but once the heat was getting high enough to damage the components inside, I gave up on gentle. Turned out the "tailcap" has no threads at all and is pressed on. There appears to be no glue or epoxy. So likely, the cap can be removed by trying to knock it straight off with wooden dowels and a hammer.
Inside with front plastic holder removed. Other than the PCB's, optic and o-rings, everything else is aluminum.
Cap that is used to change the cell. Appears to use a repurposed driver PCB. Some cleaning and a by-pass wire should reduce some unnecessary resistance.
Front without bezel and optic. That is not the stock emitter.
Pressed on cap without switch and USB covers. The metal is pretty torn up from several turns before I realized there were no threads.
Front and back of emitter MCPCB. Not much of a thermal path to the host considering the optic presses the MCPCB back. Not really a problem stock as the High mode is only 1.5amps.
Back of PCB for switch/usb port.
Front of PCB for switch/usb port. The chip labelled "57b1" is a li-ion charging IC TP4507. It is supposed to be operate like the 8-pin TP4506 common in many of our chargers, but is in a SOT23-6 package and limited to 500mA maximum charging current. This is great news and a very nice and unexpected feature in a sub $10 light.
Some side-lit pics to reveal traces on the front of the emitter MCPCB. The dark 5mm thing may be an IR emitter. It leaked red dye from underneath when cleaned with alcohol. The XP-L was installed by me. The stock emitter appears to be a Chinese mystery emitter that has about half the output of a decent XP-L. The stock emitter did have a nice neutral tint and a floodier beam profile as it was much larger.
Back of emitter MCPCB. The pads that appear to for an LED emitter (Left edge of second picture), are emitter pads. they are wired parallel to the front pads. Folks that mod drivers will notice the fried resistors in the second picture. I did that being careless. They are parallel current reducing resistors labels "1R0". So there is 1/2 an ohm of resistance on the positive side of the LED. Haven't trying to study the circuit any yet. The 3-pin chip labelled "2306YR 4t" appears to be a FET with it's Drain is connected to Negative LED pad.. There is a dot under the "2". The 1K ohm and 10K ohm resisters might be PWM series and pull-down resistor set. Haven't studied the circuit yet.
Some pics to help identify components. Couldn't make out any markings on the 8-pin chip that appears to be an MCU. The diode is marked "S4". The ? chip is marked ".J3Y".
Li-ion charger chip. The switch was melted when the "tailcap" finally started to turn and made contact with it.
Will add some info on the threaded cap soon.
Really like this headlamp. Other than swapping in XP footprint emitters, it's not very mod friendly. It is a bit hard to land on the lowest setting as the ramping flies through the low end fast. Also with the IR switching mode could use memorized level instead of just the highest level.
Modification I would like to make:
Got a couple mod ideas. Definitely want to go with an XM-L2 for more flood. The traces around the emitter pads are big enough to clearance for an XM footprint. Will also have to round off the corners of the emitter to fit the optic. Should be easy enough. Also, want to increase the current moderately. Just need to change the current resistors. Would like to improve thermal patch to host. Got an idea that will help, but won't be good enough to make high current mods a viable option.