BLF A6 FET+7135 Light Troubleshooting and Mod thread

That sounds like a bad driver… You should contact Banggood for a replacement light. Be prepared to play some customer service games, but send them pics and a video to show them it doesn’t work.

Your troubleshooting sounds as thorough as it needs to be. There was some talk about the tail switch having the lit tailcap PCB for the K6/X6, so maybe check by removing the tail cap retaining ring and removing the switch… If you see components next to the actual switch body on the PCB, post some pics and we can see what to do…

Should I cancel my order? This thread makes me want to do that. I ordered one just today, but I have no intention of dealing with whines or modding. Is it worth it?

I would say this light is worth it. I have both group buy and the lights that came out after. Think of it this way… People aren’t coming to this thread to praise this light. They are coming here to ask questions. My friends and I have 7 of these between us with zero issues.

Try the paper clip under the driver retaining ring. One occasional issue was the threading for the retaining ring not being cut far enough into the head. This means the driver only has contact on one dude and isn’t clamped. The driver is press fit so it doesn’t feel loose even when contact is poor. The driver needs to press bare metal on both faces or it might behave this way.

Hi everyone and thanks for all the suggestions and help, and I’ve started the process with banggood.

I did some more debugging focusing on the head unit, photos attached.

With the multimeter in continuity mode, I can turn the bulb on in two ways:

- touching multimeter positive and negative leads directly across the driver board positive and negatives -

- touching the multimeter positive to the spring at the back of the head unit and the negative multimeter lead to the driver board’s negative -

I have evaluated the connectivity of the outer silver ring at the back of the head unit, and it doesn’t appear to be connected to anything. Is this the driver retaining ring the previous poster (Rufusbduck) was talking about? I don’t get any continuity signal when touching it and any of the following: the middle gold ring, the spring, or either the positive or negative connection on the front of the driver board

What’s the next step - can I pry it up and try and make it connect to the back of the driver board (connect to the “dudes” referred to in previous post) somehow?

Thanks again,

Michael

Looks like your ring was forgotten. The driver is only held in there by friction.
Demand a new head (or just a ring, if you are willing to fashion a tool to screw it in).

The head should look like this, from the OP:

Sorry my bad I should have clarified that I removed the ring from the back of the driver to check connectivity.

If I put the retaining ring back in the head, with or without a paperclip below it, I don’t get any continuity between the retaining ring and any of the connections on the front of the driver board (building on top of previous tests, where without the retaining ring in the head the only way I get continuity from anything at the back to the front is by connecting multimeter leads to the back spring and either front connections.

The PCB ground track will not show continuity to either of the two LED terminals. The active part of the driver sits in series between the ring and the LED cathode.

Try to measure with a fine-tipped probe for continuity between the ring and the sliver of driver track that protrudes from underneath the ring. Alternative to the paperclip: You can add 3-4 bumps of solder to the driver ground track, if the ring does not make good contact or does not screw down far enough.

Soldering on some of these drivers is not great. The next thing to check would be the other side of the driver. It should come out without excessive prying.

OK thanks again for your support, some significant progress and a further question after following your suggestions and insights.

There is good continuity between the head retaining ring and the sliver of driver track that protrudes from underneath the ring, both with and without a paperclip. So that part is fine.

I then reassambled the light (I have periodically done this) and was able to momentarily get quite a bright light (blinded me) output. It was intermittent, sensitive to physical movement and tapping of the light, and turned off most of the time. This would suggest to me the possibility that there’s a dodgy solder somewhere…

So next step is what you suggested - checking the other side of the driver. I’m just not 100% sure about how hard to pry it out - do I pry it out from the light/star side, or from the spring side (from the light/star side, there is a metal plate below the light board which doesn’t look very movable)? With the retainer ring removed on the spring side, the driver appears to be “stuck” in place (possibly with some adhesive?) and won’t budge easily with some exploratory tweezer work. Do I need to melt something or just pry it out by inserting something sharp into one of the two slight indents between the silver ring and gold ring:

To remove the driver , you have to desolder the wires from the LED side .

Thanks, I did see that in the instructions, but even now with some “play” in those wires, the driver seems fairly stuck - to confirm, it should (once LED wires desoldered), come out through the back of the head unit or the front?

From the back of the head , as your photo shows on your previous post .
Even how it is , it should move a liitle out .

The driver should not be glued. It is typically just the perforation remains, from where the PCB was attached to the bigger sheet of driver boards, that makes it a tight fit.

You need some kind of sharp pick to gently pry/hook/pull on the the two flat edges. You can also use something like a toothpick to push from the other side, through the LED wire holes, at the risk of damaging some components on the PCB.

Just to clarify, the led is soldered to the red metal core printed circuit board(mcpcb) and the driver pcb which you only see from the spring side has all of the control chips on it. Use a tooth pick rather than anything metal and just push it through one if the led wire holes to push the driver out of its seat. It’s just a press fit. The retaining ring pressing on the driver is what grounds the driver to the bare metal of the seat it rests in allowing current to flow between battery , the switch, the tube, the head, and the driver which controls current on the side of the led. Battery + feeds both the driver and the led so you should have continuity between the spring and led. Sometimes one of the solder bumps on the led mcpcb is too tall and shorts to the reflector. If that happens on the led- bump the driver is bypassed and you get single mode Direct Drive. If it happens on the led side you get no light and possibly an overheated spring(loses temper and spring compression) which looks darkened. Even if you fix the short the spring has lost it’s temper and generally doesn’t maintain battery contact well leading to intermittent operation. If the springs look good then chances are at this point that is an issue with the driver, either poor soldering or a bad component. When you pull the driver inspect the wires where they pass through the holes for any cuts as sometimes the mcpcb will twist as the bezel is tightened and the insulation gets cut.

Has anyone noticed any issues using this driver with the new Nichia NVSL219C D320 triple board?

More specifically in a 15 amp Convoy S2 triple with all springs bypassed, 30Q battery, copper heatsink soldered onto pill, and MCPCB soldered onto heatsink, strobe mode only works sometimes. Not most of the time.

It strobes a few times, then either goes into moonlight mode, or shuts off completely. Sometimes it strobes only 2-3 blinks, then does this behavior.

I had built the light originally with the driver in the Kronos X6, and it also acted weird. With a 30Q, turbo mode only lasted a very short split-second, and strobe mode was non-functional. When I used an NCR18650B, it behaved normally and everything functioned fine. It seems like it has something to do with the amp draw, but I’m no expert.

Ok, how do I program this thing. Cannot figure out how

Thanks - I’ve desoldered the led but can’t for the life of me get the driver to pop out of its seat (have removed the driver retaining ring). I’ve tried multiple toothpicks, tried hammering on the toothpick, they just break after a lot of force is applied. Have tried picking at the driver from those two slots with tweezers, but it won’t budge. Tried running the soldering iron around the outside of the driver to “loosen” any imaginary adhesive or solder there but no luck.

Have even tried (bad probably) pulling on the driver spring with pliers but no luck!

I’m going to ping back banggood again.

Arrrgg

M

I feel your pain. Modding isn’t always straight forward and often ends with more damage than you started with. I haven’t seen one quite as stuck as yours but statistically somebody had to draw the short straw. Under normal circumstances solder won’t adhere to aluminum and I haven’t heard of them using glue but stranger things have happened. It sounds like removing the driver might require enough force to damage it so you should probably have a spare ready.

Yes, unfortunately a significantly amount of the time modding is spent repairing stuff you scr#wed up. And in my case searching for small parts that I dropped or just left at bizarre unlikely locations. :frowning:

Hi guys,

Recently got hold of a BLF A6 Black and just noticed something off.

Mine seems to be missing the center LED plastic gasket.

Does anyone know what how to get hold of one or is anyone else’s light is the same?

Does this missing part cause any issues to the light or beam?

Thank you.

Also posted under ‘Flashlight Modding and DIY Parts’ mods can delete that if its redundant.