Weird Problem with Modded Supbeam K40

Hey guys,

I have a modded Supbeam K40 which I bought a while ago off a member over on CPF. I think it has had the usual mods like braided springs, sense resistor mod?, copper star etc…

Anyways it has worked flawlessly until now, I went to use it tonight with freshly charged Panasonic 18650s and it turns on but is really dull almost like it is in moonlight mode and it is like this regardless of where I have the mode selector ring. Like standby and strobe etc all work still just with a really dim output. Any ideas what would have caused this? Could it have shorted somewhere? I did check the tailcap current a little while back, could i have accidentally shorted something then?

Did the torch still work right after checking the current?
Shorting would have an immediate effect.

I haven’t used it since then, so I literally checked it then put it aside. Although when I checked it I didn’t get a reading so I am wondering if I put the probes in the wrong spot and shorted something.

But I wouldn’t have thought I could short anything if it was going through the DMM. Because from a tailcap I would be either connecting the circuit or not?

Ok I have found the problem, I have tripped the protection circuit on one of the cells. They were all reading 4.2V and now one is reading 0V.

So new question… How do you reset a protection circuit?

Some chargers may be able to reset it if you put it on charge.

You might be able to reset the protection circuit by briefly wiring the cell in parallel with another good cell.

Well, that was a quick and easy fix! hahaha

Thanks for your help.

Might as well delete this thread.

Good to know you were able to fix it and didn’t end up with a dead $100+ flashlight.

Place one ‘active’ cell’s + end touching into the dead cell’s + end (they should be facing each other then), then find a short wire to short the two cell’s negative ends.

It is certainly a bit of a relief!

Every time I have a light that looked dim, it’s seems always my LED is fried :bigsmile:

luckily that wasn’t the case for me! haha