BLF A6 FET+7135 Light Troubleshooting and Mod thread

I'm loosing faith in my 14 AWG DMM lead setup now, after hearing these crazy #'s... Wow! Is there any reliable way you have to measured tailcap amps on the same setup you used the clamp meter on?

I'm seeing the same as you Dale. Generally months later, #'s go down, not always though. My triple X6 that was ~4200 is now like 3900 or so, for example. Cells sure do lose it. I'm think'n I'm not smart bout storing them lower - I tend to keep my cells charged up, which is probably not helping.

I also wanted to state that while the differing tube lengths are a crappy ordeal esp. for any protected battery people (although springs on both ends helps) that the tube length in itself shouldn’t affect power through the light. The problem it seems is the length of the threads and/or how deep the caps are threaded. You’re running out of thread before the un-anodized portion of the tube is seated properly. Also be sure that your retaining rings are tight as they need connection to their respective boards! As I and DB have mentioned be sure your tube is not reversed (clip slot near tail). I am already guessing you are thorough enough to have checked that. :wink: Please be aware that some of my posts are for anyone reading in the future as well.

Hi Tom, just measured the A6 that hit 6.7a on my fluke clamp meter. It reads 5.4a on my Klein DMM with 14” 12g a leads.

Occasionally I will interrupt the negative lead on the star and put a loop between the lead and the pad to clamp onto, thus getting an actual emitter amperage reading. I keep the loop as short as I can fit the clamp meter on comfortably, usually about a 3” lead.

12 ga solid wire from Romex in about 3” lengths and folded over on one end to fit in the DMM give very close to the same readings as my clamp meter. You just have to be careful not to be measuring something with more than 10A draw. My clamp meter reads up to 40A.

Hi Scott - hhmm, that's interesting. What exactly is the technique you are using with the clamp meter? It could be a true 6.7A, but maybe you won't see that high # when all is assembled and buttoned up? Usually a light box/sphere is the ultimate test, if you can test output while doing the amp measuring method, then test it fully assembled. I've seen my tail amp measurements reading low sometimes: output is lower when jumpered with the meter, compared to fully assembled (bypass's of course).

I'm thinking you are doing it with a heavy gauge wire at the tail end of the battery/light?

Clamp meter and short thick wire is the only accurate method to measure currents in that range and with voltages arround 4V. Regular multimeters have too high internal resistance and introduce large error.
I measure arround 5A with my Fluke187 and above 6A with the clamp.

I use another way that works well. I have a 0.01 Ohm resistor (1% accuracy, rated for 20A) mounted on a piece of brass with the leads soldered into a terminal block. Not on the picture but I use two 10cm pieces of massive copper wire soldered to solid copper clamps for connectors. I measure the voltage over the resistor, current is 10mV/A.

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: