Sunwayman C20C modded with MTG2 **pics added**

I finished modding my Sunwayman C20C to use MTG2.

Here’s the finished light with Smooth reflector

And with OP reflector

I performed the following mods:

  1. Applied Zener diode mod kit to 3.04 amp Nanjg 105c with DrJones Lumodrv firmware. I have to say, the kit was GREAT. Richard’s instructions were excellent! I’ve never soldered anything so small before. The resistor and diode make 7135 chips feel gigantic.
  2. After performing the zener mod I wired it up to a momentary switch and 2xAA battery pack with 2x IMR14500 in it. Success! It lit up and the zener mod worked on the first try!
  3. Next step was to gut the host and take a look inside. For this mod I chose a Sunwayman C20C Tomahawk. This is a fairly small 1x18650 sideswitch light. The head is removable making for easy modding.

(a.) Unscrew the bezel and pull out the lens, o-ring and reflector. Then remove the plastic isolator and desolder the star. The C20C has a single-piece head with no pill.
(b.) Unscrew the body tube to get to the back of the head. Use snap-ring pliers to turn the plastic retaining ring. It was glued in with some clear threadlocker of some kind and took considerable force to start moving. Fortunately, it then easily unscrewed.
(c.) The driver is a single piece. The microswitch is attached directly to the driver. The indicator light on the bottom of the C20C is actually just a window and didn’t need to be touched. The driver makes negative contact by resting on a thin un-anodized ledge that goes all the way around the inside of the head.

  1. The C20C’s driver is much wider than the 105c. I needed to make the new driver wider and attach a switch to it. My initial attempt to solve this problem was to use solder braid to expand the width of the new driver. This didn’t work, so I ended up making a new contact plate out of some hard plastic I had laying around and then attaching the 105c and the microswitch to it. I super-glued solder-braid around the edge of the new contact plat for negative contact. The advantage of using a contact plate is there’s pretty much no chance the driver will come out of position and negative contact is very secure.
  2. The new switch I installed was a Radio-Shack micro-momentary tact switch. It’s a very flat switch, but is twice as wide as the C20C’s original switch. This switch was attached to a slot in the contact plate with arctic alumina and then soldered to the driver.
  3. The Star: at 20mm it’s just a little too big for the 18mm LED compartment. I filed the edges of the star down by hand until it fit.
  4. Soldered on the star and tossed in some batteries… it works!!!
  5. Next step: the reflector… the opening is just a little too small for the MTG2. I put the reflector in a vice then used a small round file to file the inside of the hole. Finally got it about right. I wasn’t too pleased with the smooth reflector’s beam pattern so filed down a spare orange peel reflector until it fit. The OP reflector was originally from a Roche F12.
  6. I initially tried a self-adhesive XML isolator from CNQG and widened the opening with small scissors. That didn’t work very well. The isolator actually took off the top of the emitter outside the dome. I ended up coating the bottom of the reflector with arctic alumina and then using a hard plastic isolator (widened with a hole punch) to get the focus right.
  7. I applied solder braid to the spring. The bottom of the spring was actually in a round slot and was tricky to remove. Fortunately, with a little effort I got the hang of it and it came right out.
  8. I then stuck it all together and completely reassembled the light.

Here’s the new driver with attached contact plate and switch. I superglued a small circle of aluminum sheet on top of the switch button to get it the correct height:

A pic of the driver compartment of the pill-less head and the new driver:

The back of the head showing the new driver installed in the head. I used the original plastic driver retaining ring.

Initial Impressions:

  • It’s VERY bright. Probably at least 1700 lumens. Much brighter than my single XML lights. However, it’s ALL flood with a huge wide hotspot. This light puts out an enormous wall of light, but has less throw than my modded XTar wk42 with neutral XML2 and 3.04 amp Nanjg 105c.
  • At max power the head gets very hot very fast. There isn’t enough mass to dissipate the heat at that setting. Even at 25% power it gets fairly hot. During construction I cut 3 copper disks to be glued to the back of the LED platform to serve as a heatsink, but there wasn’t enough room in the driver compartment for them. I could probably have gotten them to fit, but doing so would’ve required me to skip the contact plate so the head wouldn’t be nearly as secure.
  • The tint is beautiful, but the beam has a few rings in it from the smooth reflector. The beam looks much better when I installed the OP reflector. This light isn’t a thrower though. My smaller XML2 light drawing half the wattage has noticeably more throw. The modded C20C has a very wide hotspot (at least 2x as wide as XML2… and maybe even wider), and a very wide spill.

Here’s a beamshot with the OP reflector. This pic shows beam pattern only. It was taken from close range on a blue colored wall with my iphone at default camera settings.

Very nice mod Firelight2. Welcome to the heater club. Welding gloves are not optional. It sounds like you are getting yourself one very nice light.

Dang,this light truly deserves the title of “tiny monster” very cool mod.Post some pics when you finish,I think the end result is going to be really cool.

Original post now updated with pictures :slight_smile:

very nice job

i’m seriously considering one of these pocketable mtg2s for next year’s winter camping season lol

nice mod man.

Very nice mod, thanks for sharing.

There’s no going back…you’ve taken the plunge and are now infected with MT-G2itis! :slight_smile: Be vawy vawy kaerful! You’ll find yourself wanting to stick that big fat emitter in everything! And craving more power, more lumens, more heat and then you’ll discover copper in big chunks and you’ll never be the same again! Bwaaaahahahahahahaha!

Ooops! Sorry! Nice build.

Very nice, especially when paired with a DrJones driver.


I really like DrJones’ drivers :bigsmile:

Very nice mod, and a useful light too, thanks for posting.