Hey gang! We have some bad weather heading our way. So I’m getting all the flashlights charged up (as I’m sure many of you all do too ). And I remembered I’ve been having an issue with my original BLF Q8 from loooong ago. Here’s the video:
It will not go to turbo, and just flickers. Sometimes turns itself off. I checked the batteries. I can take the same batteries, put them in my spare Q8, and it works just fine. It seems to be an issue with this particular light. One thing I did notice is the screws, on the one I’m having issues with, are raised (pan head). Whereas the one that works great has flush mounting screws (countersunk).
Well I just got done tearing the whole thing apart. Everything looked fine other than a little bit of dirt/dust inside the lens (which is odd). Rewired the driver. Problem persists…
So I decided to try all the parts from my working Q8 and see if it for sure is the driver. To my surprise, the head/driver on my “bad” one works great on the tube/battery/tailcap combo on my working on. So I eventually figured out that it must be the tailcap circuit board. I’ve swapped every combination and the tailcap is always the common denominator. I checked the springs for corrosion and cleaned them off with isopropyl alcohol. All the springs look brand new and are all soldered in very well. So I’m guessing it has something to do with the circuit board itself.
I’m glad I finally narrowed it down after all of these years, but now I’m gotta try and fine a replacement. If anyone has spare parts to a Q8, I’ll happily buy them off you!
Maybe you could try lightly sanding the bare end of your body tube to freshen up the contact surface, and remove the faulty PCB to see if there’s an obvious problem with the way the board contacts the body, such as partial anodize removal, or an obstruction.
This!
Take the tail cap apart and clean everything. Maybe use some fine sandpaper to clean any contact between the actual tail cap and the board. Clean the contact area on the board where the body tube contacts it. Clean the end of the tube where it contacts the tail cap board. I often use a large pencil eraser after light sanding, then clean everything with alcohol. If you have any around, you might try using contact cleaner prior to reassembly. I found DeOxit red and gold to fix all kinds of different electrical contact problems. Reassemble and tighten the tube to the cap snugly. I have had problems such as this many times on different lights. The issue is there is high resistance somewhere. Most of the time the above has solved the problem.
Charge up each cell 100%. Stick 'em in, run the light down for as long as possible, eg, high but constant light vs turbo and blinking. Then measure each cell individually.
A bad tailcap/board might not be making contact with all the cells, and might be using only 1 cell vs all 4, hence blinking a warning or whatever that is.
The point would then be that the cell(s) that’re connecting would be down to 3.8V or so, and the no-contact cell(s) will still be at 4.2V.
I didn’t have a problem, but preemptive bypassed the springs down-under. And the bottom plate itself.
Of course there are four springs. Each spring has it’s own lead to a screw that connects the bottom plate to the body.
This is the bottom plate of a Sofirn Q8, but I suppose they are almost identical to the ones on the BLF Q8.
Well, I figured out what it was! It is so dumb you guys are going to laugh
I took all of your guy’s advice. I started by swapping the tailcap board over to my working Q8, and it worked just fine. Worrub918, I was wondering about the screws as well. Maybe they were some horribly, non conductive cheap metal material. Nope, worked just fine.
So now I take the tube and try it out on the working flashlight. It has issues OK so now I know its the tube itself. But I’m wondering… how the heck could a solid piece of metal have an issue?? So I took yall’s advice and used 2000 grit sandpaper on every non anodized part. Isopropyl alcohol… Put it back in the working light. STILL HAVING ISSUES
So now I’m thinking… “how the heck is this tube any different than the tube that works just fine!!!”
ITS THE ******* ***** ** ***** O-RING!!! These things are what… 8 years old. I think the o-ring is slightly swollen, or has loosened up a little bit. And having it too high was causing it to get screwed in, deform, and then cause a connection issue
Silicone applied… Self-esteem bruised… I think its time for a beer
Thank you all for your help and insights! With having 2 young kids at home, I rarely get to visit this forum any more. But I can see it’s still running strong with how quickly everyone gave their helpful suggestions! Cheers
Yes… often when I have gone through the cleaning process I mentioned above, I have found other things that were causing the problem. But still it comes down to poor electrical contact somewhere in the path. Just different ways for it to happen.
). And I remembered I’ve been having an issue with my original BLF Q8 from loooong ago. Here’s the video:
OK so now I know its the tube itself. But I’m wondering… how the heck could a solid piece of metal have an issue?? So I took yall’s advice and used 2000 grit sandpaper on every non anodized part. Isopropyl alcohol… Put it back in the working light. STILL HAVING ISSUES 
These things are what… 8 years old. I think the o-ring is slightly swollen, or has loosened up a little bit. And having it too high was causing it to get screwed in, deform, and then cause a connection issue 
