Atactical A1 / A1S Driver Mod

Flashlight Modding and DIY Parts
1

Has anyone tried modifying the driver for the Atactical A1 / A1S ?

I took apart my A1 and the driver is lightly glued in and can be pushed out with a rod from the front. The side switch button doesn’t look like it needs to be removed for the driver to come out as the switch is on the driver pcb shelf, but I removed mines before I tried pushing out the driver.

There is a control chip marked LB3V.
A constant current driver marked OC7131.
A mosfet marked 143 B16 KIA30N03B
A current sense resistor? marked R024.

The data sheet for the driver is in Chinese and isn’t clear on how to calculate the resistor values needed. I think it is an issue of formatting or translation. I am guessing the formula is I-led/R-cs= 50mV. I am looking to boost the current to at least the 3A max listed, or maybe more. So for 3A, Rcs should be 0.016 ohm, and I can get close to this by stacking on a 0.05 ohm resistor. Does this sound right?

There is also a mention of being able to drive 6v LEDs, but doesn’t list the components needed to do so.

Datasheet link:
https://translate.google.com/translate?hl=en&sl=zh-CN&u=http://www.wendangku.net/doc/d479b017f705cc1754270995.html&prev=search

2

I tried stacking the resistor with a 0.050 ohm, and got no change in measured current in all modes. My multimeter is from harbor freight, so I couldn’t measure what the final resistance was. I tried different batteries and multimeter and got the same result.

I also swapped the led with a dedomed XPE2T, which seems to do well in this reflector. Centering it was a pain though.

3

How did you take apart the A1? Does part of the head unscrew?

4

Disassembly quick guide:

  1. Unscrew tail switch and remove battery
  2. Unscrew battery tube
  3. Unscrew front bezel/cap?, the point where it meets the head is hidden between the two cooling fins nearest the side switch
  4. Unsolder LED wire leads
  5. Remove MCPCB screws
  6. Punch out driver from MCPCB screw hole opposite side switch

Notes:
-Mine had no thread lock anywhere, try using a rubber glove or strap wrench if it is stuck. Rubber gloves were all I needed
-Driver is lightly glued in, mines took little force to free. No hammer needed
-Driver has no components on the side opposite the side switch, so it should be safe to punch out there.
-LED wire leads have no slack, they must be unsoldered to remove the driver
-Reflector is screwed in place, but the spacer ring can easily fall out and be lost
-Side switch button doesn’t need to be removed to get driver out
-Tested on a A1 model

I will try to get pictures another day.

5

Thanks for the steps. The bezel/cap is is the part that I got stuck on, even with rubber gloves. I think mine has thread lock in it. Arrrgh.