Hello, I am new here but I have been lurking for a while.
Recently I made a XPL-HI triple led flashlight using a noctigon xpl-hi triple from mountain electronics and a blf-x6 driver and a jaxman host. All was well.
But I decided to remove the bleeder resistor from the blf-x6 driver. So I opened up the flashlight to unsolder the wires from the mcpcb and I saw that there was some
thermal paste on the leds. Therefore I carefully (at least I hope) removed the paste with a q-tip and some alcohol. After that I desolder the wires and removed and modded the driver.
When I put it back together, it seemed like the capability for moonlight mode was gone.
I had another driver lying around, so I swapped drivers and nothing changed. I also tested the modded driver on another triple and it worked fine.
The other problem that I see, is when I get to the menu of the bistro firmware, the flashing changed. What I mean by that, when it flashed before it was like on off on…etc. Now it is on-dimm but not off and on again.
Does anyone had a similar problem. It seems like the pcb problem, but it seems really weird.
I found what is the problem I think. When I soldered the driver and the mcpcb and left it outside of the flashlight, it worked fine. The problem surfaces when I put it inside the host.
I measured the resistance between the point where I am supposed to solder the black wire (negative) and the bottom of the mcpcb and the resistance is 0 Ω. Is that normal?
From what I understand it bypasses the minus the black wire of the driver and it gets the minus straight from the battery.
I also tested my theory by connecting the mcpcb with the driver outside the flashlight and feeding the negative straight from the battery bypassing the driver.
I am guessing there is something wrong with the mcpcb and not with the host. Am I right?
If the LED negative is shorted to ground the light would be direct drive. It would just have the one mode. Maybe there is a high resistance connection between the LED negative and ground. This maybe would cause the behavior you described in the OP. There would always be some current flowing to the LEDs which would change the moonlight mode and cause the on-dim blinking you described. It does sound like it is something on the MCPCB. It could be a small connection between negative and the thermal pad under one of the LEDs. Post a picture if you like.
The fact that you are changing the resistance of the short just by wiping the MCPCB makes me think it’s something like a chunk of solder wedged somewhere it shouldn’t be, like between the thermal pad and negative of one of the LEDs or something. So I would suggest looking closely at these areas with a magnifying glass.
You’ll probably need to heat it up till the solder flows and that should take care of any solder btidges from -pad to thermal pad. There’s not much else that could cause a direct short in this case.
To be honest, after I heated the triple on a pan and nothing changed I was ready to give up. I though I have a defective mcpcb and I though I will buy a new one. So I removed the leds and the bridges and found that the short was gone. I placed the leds and bridges on again, but there was still a short but with a big resistance. So, to the pan again removed everything and examined the mcpcb. This is when I realized that the thermal pad is connected to the middle stripe of the led “position”. So I tidied up all the soldering with my soldering iron and then gave it a good scrub with a scotch brite and some dish shope, resoldering everything and now I have a flashlight again!!! Also, now I know that I can reflow leds!
So thanks again for everything. Your help was invaluable.