BLF A6 FET+7135 Light Troubleshooting and Mod thread

That is indeed more accurate than a multimeter but still there are 10mOhm plus two wires added into the current path (let us assume 20mOhm total including the connecting wires, connectors and soldering).

20 mOhm multiplied by 6A produces a 120mV voltage drop.

This may not seem much but with the exponential VA curve of the LED 120mOhm will give you a difference in the measured current of at least 0.5A. See the attached Cree XML diagram for example.

For comparison I use a wire for my clamp that is less than 2mOhm.

I'm not sure the connection set-up for the sense resistor gives another 10mOhm (I hope less), I did not check that but I can do that and report here, I'm curious too (not before tomorrow btw). The 0.5A drop at 120mA is also correct for the XP-L at 6A btw.

So. All the modes on the light work except moonlight. It is basically off. Do you think touching up the solder on the 7135 will fix this?

Battery charged? You could check out post 52.

I’d touch em all up… The first four modes run through the 7135 no fet. Then 7135 + fet on 5 and 6. If you have any modes at all with your light then 7135 is working. Others may chime in……

Programming?

I’m a modder and we are all more patient but I really don’t have a ton of time for troubleshooting. I’m not very happy about this.

It’s a freshly charged new LG HE2.

Actually dudunphy, that’s not quite right. ToyKeeper posted a list of how the two channels work together earlier in this thread…

The modes are:

Group 17135 power__FET power
Moon_0.8%…………….0
Low__8%…………… 0
Med 1__43%…………. 0
Med 2_100………….2.7
High 1_100………….22
High 2_100………….54
Turbo__0………………100%
Group 27135 power__FET power
Low__8%……………0
Med_90%……………0
High__100……………35
Turbo__0……………….100%

So, modes 1,2,3 work on the chip with no mosfet(or 1 and 2 in Group 2), all the other modes except turbo have a blending of the two. Turbo being 100% Mosfet for maximum output.

Point being that it might seem to be working “fine” on all modes save moon, with that one being off apparently. This is showing up as a common problem on this light, either they had issues with soldering the 7135 or they got some bad chips, which can happen.

Ok. I’m Pretty po’d now. Tried remelting the connections (they all looked pretty good) and still have no moon mode. Time to contact the professional guy. Waited over a month to get a non -working light. This sucks.

Crap. Sorry Gunga. Hopefully you get a new head and you’ll have a spare to mod in the end….

Also thanks D.B. I was trying to do that post from my smartphone in the middle of some auto repairs. The fun never ends! :slight_smile: :_(

Oh well. I think I have a friend who wants it. Warts and all. Thanks a bunch for the advice. Too bad it didn’t work. I’ve contacted the professional guy and will await a response.

Hey Tom, sorry for the slow response to your question. The method I now use to measure amp draw at the tail is this (thanks to Dale);
I use a 3” piece of 12ga, solid copper romex, bent into a u shape. I then do the standard bypass procedure on the tail. As you can see my readings have went up considerably since I began using this method. I, like you, was frustrated at how much different my readings were compared to other peoples, even on the same lights. The A6 that I won in Dale’s generous giveaway showed somewhere around 1A less than he achieved, when I received it and measured with my “thick short leads”.
Here’s an FYI to add more data to this topic. I bought 2 A6’s in this GB. 1 with 3D tint bin, the other with 1A tint. The 1A was the light that hit 6.7a after both springs were by-passed. I have now done the same mod to the 3D light with different results. 5.9a@4.18v with the same 25r cell, measured with the clamp meter. So it appears that binning does have something to do with the hi amp reading (as mentioned by Djozz, and Dale.
I never got around to building a “light pipe” to measure lumens, so I don’t have that data to add to the story. I did however, measure before and after lux on both lights and will post if anyone is interested.

I really dunno what's going on. I used to have a pretty high confidence in my UNI-T DMM equipped with the 14 AWG short length wires. It's certainly dead-on with 7135 based drivers all the way up to 4.9A or so. I work with a super tech who swears the internals for measuring amps in the UNI-T is as good as any Fluke meter. This guy has like 6 UNI-T's he uses regularly, plus a couple of Flukes. It's hard to describe this guy (the super tech), but he is one of the smartest people I know, so I always have a high degree of confidence in what he states and recommends, when he is serious that is...

I know there's a lot of anomalies going on at times in my measurements - things I can't explain. I suspect mostly it's contact/ground issues. Wire ends need to be cleaned or re-soldered (oxidation), contact by holding a wire end against the lip of a light tube is not always the best method, etc. Still, there could be major inaccuracies in 5+ amp range I didn't know was there.

If moon doesn’t work but everything else does (modes 2/3 and 3/7 should be visibly different from each other), it’s also possible that the 7135 chip could be a different type. The 350mA ones generally have a lower and more consistent moon level than the 380mA ones, and I expect there are more than just two types.

The firmware says to use 2/255 phase-correct PWM, which actually works out to 4 on “frames” in a row out of every 512. Some 7135 chips need 3/255 or even 4/255, and it also depends on the type of emitter. Old XM-L LEDs need a higher moon level than a newer XM-L2 or XP-L.

In other words, moon is pretty sensitive to relatively small hardware changes. This is a lot of the reason why cheap torches generally don’t have moon at all. And if any component changed or was out of spec, it could cause moon to fail without visibly affecting anything else. I hope BG can send you a new driver.

Or, you know, it could be a symptom of the lunar eclipse which is currently happening outside. Even the real moon isn’t working right now. :stuck_out_tongue_winking_eye:

Ha! Cool. You are correct TK. I have many Dr Jones programmable drivers with super low moonlight modes. They are quite inconsistent depending on the hardware. I think you are correct in your theory. Good call.

Yeah, even the real moon is wack… I tried to pull it back in line with a tractor beam, I think it worked :wink:

Dale, did you make that pic during the lunar eclipse? That's way cool!

I'm a bit confused here .. you have two lights that work . why not just figure out whats wrong with it and fix it . they don't all have to lego since they are the same light .what does lego have to do with it and what would you do with an extra couple bodies and a tailcap?..

sounds like you need a body or a taillcap . not three .

at this rate it may just be more prudent to do some work on the tailcap if you can ...it sounds like what you have is a common problem on some of these lights. but what do i know i'm still waiting on mine ( while you guys are having all the fun )

i still reserve the right to complain at a later date ...

I just checked my current sense resistor set-up with the power supply set at 6.0A (ps reading=not dead accurate, ~0.1 á 0.2 A wrong): voltage measurent with probes directly on the resistor leads: 57.7mV, probes on top of the terminal block connectors (this is where I place the probes for current measurements): 60.3mV, probes at the end of the solid copper leads: 72.0mV. So the whole of connections of the sense resistor gives 2.4 mOhm on top of the 10 mOhm of the sense resistor. so the current drop from a XP-L at 6A caused by the sense resistor in the circuit is about 0.3A.

For perspective, I measured the voltage over a BLF-A6 tailcap with 22AWG silicon wire spring-bypass, measured from the top of the spring to the aluminium ridge that is screwed against the battery tube. When applied 6A, I get 124mV, causing 0.5A drop for the XP-L compared to directly connecting the batt- to the battery tube. So adding a well-build tailcap in the circuit is causing a bit more voltage/current drop, but is in the same range as adding the current sense set-up. That is convenient.

I'm happy :-)

One of the things that is contributing to what burnsd is saying is that the threads on the A6 are anodized, and so the way that the light is designed is that the end of the battery tube at the tailcap end HAS to be able to contact the retaining ring inside the tailcap in order to complete the circuit. If the end of the battery tube is “short” by some tiny bit, it won’t contact the retaining ring and you won’t get any light no matter how tightly you screw in the tailcap (so note that this is not a battery length problem either).

That’s why putting a wire inside the tailcap helps sometimes… basically it moves the contact point of the retaining ring “forward”.

I had to put a wire ring inside my A6 in order for it to work.

I have one of the unanodized A6s coming (it is taking FOREVER to get here) and that should NOT have this problem since the battery tube is not anodized, the contact is made by the threads themselves, rather than by the end of the battery tube contacting the retaining ring inside the tailcap… that’s the theory anyway :)!!

My replacement driver arrived today.

Interesting to note that it came in a bag that was sealed with an SKU number sticker.

I ran the number through BG's site, but didn't get a hit.