K40 (XM-L2 version) problem with switch! (replacement switch on the way)

The switch itself is ok, it works but when the light is fully tightened it stays always ON and clicking the switch doesn't do anything.
I removed the switch from its PCB and when I push that PCB inside the battery tube (to the place where it normally sits when the flashlight is assembled) that turns the light ON even with switch physically removed!!!
Switch PCB looks fine, springs are in their place, not bend, all components look fine (no burn marks)!
Other than this light works OK, magnetic ring changes modes as it is supposed to do...

Not sure what is going on here, any suggestions, guys?

a couple miles of kapton tape?

How is the annodizing on the tailcap where you put the switch assembly, does it have any rub marks where the metal is showing? did you look at the traces using a light from the other side? noticed anything out of place?

I am finaly back :weary:
musicmagic: capton tape is insulator and with everything insulated flashlight would not work at all.

AlexGT: Anodizing looks fine to me, that is, the part where switch assembly site is not anodised, it is conducting. rub marks! not sure what do you mean by this, maybe pics will answer! I inspected traces on the switchboard and they look just fine. Everything looks fine, no burning smell either, it just does not work as it should.

I am not electronic expert, far from it, so I do not fully understand what is the function of those electronic components on the switch PCB! It looks like it is some kind of switching circuit, switch is connected between + and - terminals of battery carrier but through this several components, otherwise something would get pretty hot pretty fast :slight_smile:
It looks like the switch is giving low voltage and/or low current “signal” for the electronic to do POWER ON/OFF !!!
If I am not mistaking, there are 2 resistors, 3 zener diodes (marked as K24, and 2 x W8 with horizontal C) and 2 x some three legged components, transistors maybe, markings: AGHV 13!!!
If I would have to guess I would say that one of those 3-legged components is sick :slight_smile:

Here are several imgs (click for original size):


Hey Sirius, I have the same problem with my K40. My problem started when I was attempting to take an amp draw measurement at the emitter, and directly shorted the wires. Fortunately, I had ordered the light directly from Acebeam, and bought a spare driver with the light. After replacing the driver I noticed the tailswitch no longer functions, at all. I have examined the PCB many times, and like you, can see nothing wrong. I also don’t understand exactly what purpose this PCB serves. Sorry I can’t provide any info, other than to say you’re not alone.

Maybe some of our local electronic gurus will jump in :smiley:

P.S. scotlarock, Could you do a quick continuity test with your multimeter between this 2 points that I marked in violet (switch should be in OFF position it that has any influence at all). Thanks

Ok, I show brief (about 1 second) continuity, then that changes to open or none. It also doesn’t seem to matter which position the switch is in.

Hm, ok thanks. My (rether old) multimeter is beeping constantly, you probably have never multimeter so it stops beeping after 1s. so, that should be same result as mine, I was kinda expecting opposite result :slight_smile:
Either we can rule out this component is faulty or the same component is faulty on mine and yours PCB, brilliant conclusion :smiley:
We need someone with working switch :nerd_face:

So, Bella from Acebeam saw this thread and offered to send me a replacement switch.
It’s on the way and in a month or so it will be here.

Sirius9, as a longtime user of this light, does it have a low voltage warning system or something?

Hmm, interesting! I am sure it does have but, strangely I never actually discharged cells in the light to the level where low batt. indicator would kick in. I have quite a few laptop pulls and at least 10 of them are freshly charged ready to use at any time, reading blf too much I guess :stuck_out_tongue:

I was browsing ChibiM’s great review and indeed it has low voltage warning and low voltage cutoff. A great light indeed.

Im very flattered DanielM, but the one I reviewed is the K40M, and not he K40.. but they might be internally the same..(on the switch side)

Update: I received replacement switch from Acebeam, it’s for K40M but who cares, battery carriers are the same.
Also I was able to find what is the problem with old switch (fet went poof), replaced the component and got it working again, so, win-win :slight_smile: but thanks to Acebeam for stepping up here.

Hey Sirius, I’m sure you already noticed but the tail cap circuit boards are different between the K40 and K40M. Just a heads-up.

Yes, but they are doing the same job, battery carrier voltage is the same so they should perform identically.

This is nothing more than a presumption on my part; I think if they performed identically, Acebeam would have used the same PCB in both lights. I’ve noticed they use a modified form of the K40 driver in the K40M, so it would seem they do not mind interchanging electrical components, from one model to the next.