I need you electronics experts to tell me exactly what resistors to change on my TR-S700 driver to bump up the output. It has 7 XM-L emitters and pushes about 10-11 amps stock (1.4amps to each emitter). Suggestions for pushing minimum of 2A-2.5A per emitter would be greatly appreciated. :)
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More power hey JM……
mwwoohoohahahahhahahahha !!!
J) 
I can dig it.
R4 thru R7 are the sense resistors, adding more very low value resistors in parallel with those will increase the current, that is, it the rest of the driver isn't already maxxed out. As a quick test you can jumper across any of those resistors with a wire and see if the output goes up.
Okay. What value is on them now? Is “0” basically a shunt?
That driver appears to be running open-loop. As such, it is outputting it's maximum possible current already.
PPtk
What's up with the unused FET pads?
edit: I have a 9 amp driver that has, no lie, at least 12 'zero ohm' resistors stacked up in a great big dogpile. So I guess if you add enough of them, they turn into negative ohms or something. :party:
R0 resistors are seldom actually 0 ohms, they are usually several milliohms. So, you might be able to squeeze a little more out of the light by replacing them with copper braid.
Along the lines of what PilotPTK is saying, the FETS themselves are resistors in parallel. Measure the Vf of one of the FETS under full load if you dare. Vf/(A/2) = R, Take half of that and you have the Rdson of that FET. Go shopping for a new pair of FETS.
Edit: edited formula
That (stacking the 0 ohm resistors) may be to increase the amount of current carried through them cumulatively?
Just a thought… maybe try replacing the emitters with XP-G2’s in the tint of your choice. They are dirt cheap and wont require copper at the stock drive current for good results. Center hot spot/throw will probably exceed XM-L and 7 of them should provide more than enough spill. You’ll also get descent run time & heat management without killing your batteries; while avoiding the higher drive currents of a driver mod/replacement.
Try the copper braid or thick wire or a big solder blob instead of the 0 value resistors If it helps, that’s about all you will get without doing resistance mods elsewhere, wires and springs. Emitter wires look kinda small for 11A.
I can’t really tell but the wires do look small for 11+ amps. If you could replace the wires running from the driver to the first emitter with 18 or 20AWG you should see some gain. The wires running from emitter to emitter should be ok as there not seeing the full 11 amps and are very short distances. Unless you do more resistance mods, then you may want to change the emitter wires to something bigger too. 2 amps to each emitter would be 14 amps from the driver. The wire from the first led to the second led would be seeing 12 amps as the first led dropped 2 amps. Second to third would see 10 amps.
Assuming the leds are wired in parallel.
If the FETs are in parallel, would adding a 3rd FET increase current(providing the cells are capable)?
thanks, guys! I will do resistance mods on it. Which components are the fets? I know caps and resistors but fets leave me confused for some reason (brain block). Any other suggestion from those in the know?
Adding a FET (Q1 and Q2 are FETs) may not do much. This thing is a switching regulator (probably a buck driver). Too much current can saturate the coil and cause all sorts of problems (like even worse performance).
Easiest thing to try first (before adding FET etc) would be to just short out the 0ohm with solder. These teenies always have some small resistance on them, which affects the gain.
I don’t think copper wire/braid is needed at to bridge this small distance, it would make little difference. Unless you find it easier to solder with.
oh boy - whats JM modding? a trj18??
Any Diode or FET behind coil ?
Buck regulators have diode or FET (synchronous) but this one have no.
I see the coil, but I don’t think it is a buck driver. The cells are in parallel, so 4.2V to the emitters in parallel… this is a giant SRK of sorts.
I added a third FET to the kung driver once, thinking it would gain some more lumens. It wasn’t a exact match to the others but it had the lowest rds of the FET’s I had. As Texaspyro said, The current out put was reduced. Had more current with the original 2 FET’s. Unsoldered it and left it at 2. Did resistance mods for some small gains on the kung driver but nothing gained that had the Wow factor.