Convoy M2 Suddenly Dim

I purchased this flashlight from fasttech april this year. I have been using this flashlight on my bike since april. A couple of days ago the light has been very dim in all modes. I do not have a light meter to measure the difference but to me the hi mode is more like the low mode before I had this problem. The batteries are freshly charged and I have tested them in other lights that work perfectly. I have also cleaned all the contact points and tried the paperclip trick. Even with the paper clip the light is still dim. I have a cheap multimeter from harbor freight I can use to test the light. I need some help troubleshooting this light.

strip it and make sure that everything is screwed down tight, from the pill to the tail

Sometimes the pill on the M2 will back out when you unscrew the body from the head. It's possible this has happened to yours. Check and make sure the pill is tight in the head and let us know how it goes. ;)

So I tried a freshly charged 3400mah panasonic and a 2600mah sanyo and still dim. These same batteries were also tested in a xintd c8 and they worked perfect. I removed the pill and tail cap from the m2 and cleaned the threads and I made sure everything was snuggly installed but still dim. Can someone walk me through how to use my multimeter to diagnose this light?

Now the light is completely dead. Tried the paperclip trick and still no light. Looks like I will have to change the driver and emitter. Has anyone removed the driver from the m2 pill? It looks like it is being held in the pill with a ring glued over it. Any help would be appreciated.

I’m going by the pics of the host that Fasttech provide. It appears that the ring is not glued in but threaded in, it simply has no notches to grab it to unscrew. Dremel or file a pair of grooves into the top of the ring and try using needlenose pliers to unscrew it. The driver itself is a standard 17mm 105C .

With the pill out, unsolder the leads from the star and remove it. The driver should pop right out if you removed the retention ring. You can test the emitter by direct-driving it from a battery. Make sure there’s something between your eyes and the emitter when you test it otherwise you’ll be seeing a dark sport for awhile. If the emitter lights nice and bright from the battery then you know it’s the driver that’s bad. If the emitter doesn’t light, then you need to replace it. (The M2 uses a 16mm star)

Thank you for this advice. The ring is threaded but I can also see white glue sandwiched in between the ring and the contact board. Is there a trick to soften the glue to remove the ring?

its unlikely the emitter is dead its more likely the driver thats shot, if you have a multimeter with diode test try that on the emitter

Maybe the emitter could be toast. I actually dedomed the emitter 3 months ago. The light worked perfectly until I started getting the dimming problem recently. I used the gasoline dedoming technique but I didn’t remove the emitter from the pill. I dunked the pill just enough so that the dome was in the gasoline only. Maybe the gasoline made it into the driver? I’m not sure but the light worked perfectly for over 3 months.

I’m pretty sure that the insulator on the star is solvent-proof. Lots of people just dunk the star. De-Doming does have the potential to damage the conductor wires onto the diode pad but if it worked then, as long as you haven’t had this thing mounted to a rifle you’ve regularly taken to the range I don’t see why it would have come unlodged now. But hey, one of the emitters in my 3T6(copy) went poof by itself (and the collective got dimmer as the one emitter died). And as long as you dried the star off it shouldn’t have reached the driver. Even if there was some residual left it would have evaporated minutes after turning the light on.

Is the substance you see in the ring glue or solder? The ring could be soldered into place. I’d still remove and test the emitter first, that way if it is the emitter you can just slide the new one in without having to mess with the driver.

I used this light mainly as a bike light. It definitely looks like glue because its white and looks like fujik when dry. I can also scrape some of it off with a screwdriver. I have a mini torch and soldering iron so I can heat the pill to soften the glue.

The driver on my m2 is held in by a threaded retainer ring. A small amount of adhesive or thermal compound is visible under the ring. I have not tried to remove the driver yet, but I will be changing it and the emitter in the near future. I should just have bought the host instead of a complete light.

If that’s the case, then I’d just try putting opposed notches or holes in the ring and using needle-nose or snap-ring pliers to rotate it. But as I said, try removing the emitter and direct-driving it off a li-ion first (only for a moment).