BLF A6 FET+7135 Light Troubleshooting and Mod thread

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xzel87
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@blightsam

 

I am aware of the dedoming risk thanks to the OP of this thread. However, it was never an issue with my defective head and new head. I took out the plastic centering piece and placed it over the led board before screwing the head back on. Didn't feel like it snagged on anything, let alone dedoming.


@pobel


I don't have an assortment of orings at my disposal, in addition, as a buyer I shouldn't have to be worried about that issue in the first place as it really seems to be a QC and maybe waterproofing design issue.

hank
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I’m fairly sure the O-ring size too small problem is already on the list, it goes way back.

xzel87
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@hank

 

I was not aware of the oring issue, if that is true, then apparently it still wasn't solved by the manufacturer despite being made known to them? Regardless, it's not really a problem because I won't be dunking my light in real use anytime soon...if i have to there are more suitable ones.

SIGShooter
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Is the water sealing issue a problem using the light in the rain? Or is it more an issue when it gets dunked? For example dropping it into a puddle.

9mm/40cal/45cal bullets and large/small pistol primers available for sale in San Francisco Bay area

djozz
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BLF-A6 driver repair.

In the process of installing a bleeder resistor for a lighted tailcap mod I managed (or it managed itself, dunno how it happened) to damage the driver of one of my BLF-A6 lights: in the 7 modes setting without memory, the first three modes became the same, quite bright, it looked like the 7135-chip did not respond to the MCU anymore and was always open. Today I spend some time (hours actually, I'm glad this is a hobbySmile) repairing it. I took the driver out and clamped it in the vice, with the ledboard re-connected loose in the air for testing with a 18650 battery. First, I tapped all the solder joints on the driver with the soldering tip to make sure no cold solder joints were leftover. Did not help. Checked every component for shorts underneath, no luck.

Then I swapped the 7135 with another one from the spare parts box. Now something did happen: very weird behaviour: very dim light from the die (like: 1/1000th moonlight), and after tapping the battery connection (=switching on/off) a number of times suddenly full blast, then extremely dim again. I tried another 7135 from the box. Now an almost complete user interface, just the moon was much lower than stock. Then I tried a few other ones and mostly got this version of the UI with extremly low moon, and in the meantime I began to watch the lettering on the chips: 35A,35B,35C,35D,35E,38A,38N, what is the difference?. There are more 7135 versions than I already thought:

(I have a few more types actually, but could not find them back for the picture). Then I soldered the stock one (the one in the bottom right corner on the picture) back for a check, and it was indeed still broken: all 7135-modes were still max. I already decided to settle for the 35D because it had the most usable way too low moon, when I thought of digging into the complete drivers box for more variations of the 7135 and sure enough I found the same type of the stock BLF-A6 driver on an ancient 2x7135 1-mode driver from dx. Tried that one and presto: the UI is back to normal, the BLF-A6 apparently needs this specific chip.

Morale: I don't know if this has already found out before, but there's clear variations in how differently marked 7135-chips react to (at least) the BLF-A6 firmware

MRsDNF
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Nice detective work djozz. Who would've guessed.

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

chenko
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So do you think that us folks with a misbehaving driver should get a 7135 chip of the “1452” type and swap it on the board? Would that solve the power off issue on mode cycling?

BTW great work, indeed.

ToyKeeper
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djozz wrote:
the BLF-A6 apparently needs this specific chip. … there’s clear variations in how differently marked 7135-chips react

Yes, unfortunately. Different types of 7135 chips respond very differently at the low end, which makes moon nearly impossible to do consistently. I suspect this is part of why so few budget lights include a true moon mode.
DEL
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djozz wrote:
Morale: I don’t know if this has already found out before, but there’s clear variations in how differently marked 7135-chips react to (at least) the BLF-A6 firmware

We expect too much from these 7135 chips. They are pretty impressive for what they do, very convenient and cheap.
High frequency PWM is not their thing though.

Most firmwares use a PWM frequency of around 7-9 kHz for Moon mode, BLF A6 included.
At 8 kHz, a PWM duty cycle of 1/255 gives us an ‘on’ pulse that is only about 0.5 microseconds long. But the 7135s need about 2 microseconds before they start to turn on and another 4 microseconds before they are stable. In those 6 microseconds the response is like an under-damped control system. We have a transient ‘on’ peak, then it cuts back and then finally stabilizes where it is supposed to be. What we see with the 8 kHz PWM Moon mode is just the transient peak at 2 us. The timing and amplitude of this peak probably depends on the exact sample of 7135, cell voltage, the emitter, wire/track lengths, etc.

The ones I measured were groups of 6 or 8 from standard 105C/D drivers. Some types may be better, some may be worse and individual samples of the same type probably vary as well.

The only way I see to get somewhat repeatable output from different sets of hardware is to slow the PWM. A lot. The smallest pulse width needs to be at least a few microseconds more than the 6 microseconds stabilization time. Lets say 2 microseconds more. So we start with a minimum pulse width of 8 microseconds. (Conservative design would select an order of magnitude larger, we do not have that luxury here.)

If we want to get this 2us margin at a PWM duty cycle of 1/255, it translates to a PWM frequency of 500 Hz (1/(8us * 255)).
Or, we can decide to not use a duty cycle lower than 4/255, then we can get away with a PWM frequency of around 2 kHz (4/(8us * 255)).
If we apply this rule to 8 kHz PWM we are stuck with a minimum duty cycle of 16/255.

Most people will, however, object to the lower PWM frequencies. We also do not get a very low Moon mode.
In the end proper current regulation is really the way to go, not PWM.

Example 7.2 kHz PWM, 32/255 duty cycle. Even at 32/255 about a third of the ‘on’ time is wasted/unstable:

Now, if we cut back to 4/255 duty cycle, all we are left with is part of the unstable transient peak:

ToyKeeper
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DEL wrote:
Most people will, however, object to the lower PWM frequencies. We also do not get a very low Moon mode.
In the end proper current regulation is really the way to go, not PWM.

Agreed. At the 2kHz speed you described, it looks like a strobe light to me. And proper regulation is nice to have.

Proper regulation may be difficult, since it requires more hardware and might use an extra pin. On BLF-A6 there is an unused pin… but probably no room for another component or two. I wonder if we could make it power the LED directly from the MCU. It’d probably require a resistor to adjust the current to the correct level, but otherwise I think it might be feasible if it’s only used for moon. Then there would be three power channels — moon, 7135, and FET.

The 7135 abuse method seems to work well enough most of the time, if people aren’t too picky about the exact output level. Like on the A6, it seems to range from 0.26 lm to 0.55 lm, possibly more. Pretty wide range, but they’re all reasonable for “moon mode” use.

mattlward
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Has anyone seen this before? It looks like the light settles into a mode, notice the flicker and then it is stable? Please disregard the auto exposure, can’t change that on the phone video recorder. I am going to send a note to Neal, I am afraid it will quit altogether. I have used Keeppower 35A and 30Q batteries, verified the switch is tight and cannot disassemble the head. Sad

Flicker data-flickr-embed=“true” href=“https://www.flickr.com/photos/98509702@N05/21981754936/in/dateposted-public/” title=“20151006_202105_001_001”>20151006_202105_001_001

Matt

EDC rotation:
FW1A, LH351D 4000k (second favorite)
FW3A, LH351D 3500k
FW3A, SST20 FD2 4000k
FW3A, Nichia 4000k sw40 r9080 (favorite light!)
FW3A, Cree XP-L Hi 5A3
Emisar D4V2, SST20 4000k
S2+, XM-L2 T6 4C

MRsDNF
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To me it appears to be a crook earth somewhere.

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

mattlward
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Very hard to do with a camera that cannot be set to manual exposure! And it happens so soon after mode change that the exposure does not get time to settle in.

EDC rotation:
FW1A, LH351D 4000k (second favorite)
FW3A, LH351D 3500k
FW3A, SST20 FD2 4000k
FW3A, Nichia 4000k sw40 r9080 (favorite light!)
FW3A, Cree XP-L Hi 5A3
Emisar D4V2, SST20 4000k
S2+, XM-L2 T6 4C

xzel87
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Same thing happened with my defective head on mode 2, 3 and 4. Will flicker for abit then settle down. Didn't see this behaviour in my new replacement head. Most probably bad solder (as usual) on the 7135 chip. Ask banggood for a head replacement.

Lilien
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If we speak about flickering, I see my A6 flicker after I switch it to the highest mode (turbo), there is a single short flicker (reduced brightness) after about half a second, not every time but often.
I know there is a unwanted flicker after switching from turbo to moon, but this is the other direction. Is this the sign of a problem or normal behavior?

I also would like to know if you would advise me to remove the MCPCB, which seems to be a forced press-fit as shown in the first post – is there a good chance that I can improve the heat transfer?

THAO916
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So just an update on my A6 5A head replacement; I received it a few days ago & all is good! :bigsmile: Now all 4 of my A6’s are together again lol I’m lovin the 5A tint more and more.

THAO916 wrote:
FYI
I found this info by chance checking my orders and updating delivery dates.
Anyone who is supposed to receive replacement parts, please check your banggood order and click on the tracking number. IF your replacement has been sent to you, it should show new shipping information. I have yet to confirm this, but I will let you all know hopefully by tomorrow because my updated shipping for my order has just arrived in LA today. I am hoping it is my replacement head for my A6 with the 5A tint.

Wish you guys luck!

Herpaderpadeeee
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Can I use two CR123a batteries rather than one 18650 safely?

I have some surefire 123s laying around, and my 18650 got lost in shipping and won’t be here for a month or so. But my BLF a6 showed up! I really want to play with it, so i was wondering if i can use two cr123a batteries without hurting the flashlight.

dudunphy
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I don’t think so. Too much voltage.

Edit: If you’re that excited you could use one and somehow spacer it. But two in series will make 6 volts+

Dustin

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Ahhh shoot. Thanks for the quick reply.

There arent really any alternatives are there?

dudunphy
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Edited above.

Dustin

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mmm… seems pretty complicated and a little bit above my head. Thanks anyway!

The waiting game is in full force. Quickly import / exporters!

keengeorge
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Herpaderpadeeee wrote:

mmm… seems pretty complicated and a little bit above my head. Thanks anyway!

The waiting game is in full force. Quickly import / exporters!

If you want it quickly, & you are in the US, then order from Richard/RMM at Mountain Electronics

BLF Thread:

MTN Electronics: LEDs - Batteries - Lights - Chargers - Hosts - Drivers - Components - 1-Stop-US Source

http://budgetlightforum.com/node/25986

 

Batteries | Mountain Electronics

http://www.mtnelectronics.com/index.php?route=product/category&path=59

 

Richard/RMM has Great products, VERY GOOD prices, VERY FAST shipping, and GREAT support.

 

Best Regards,

George

 

 

ToyKeeper
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Illumn.com is pretty awesome too. The focus there is more on name-brand lights, but both stores have batteries and great service.

And, no, don’t try to use two CR123A cells. It will fry the driver, which has an absolute maximum of 5.5V, and it might fry other components too.

Rufusbduck
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The A-6 is an ideal light for candle mode operation so if there’s a diffuser that fits with the head removed could someone mention it so it can be listed in the op?

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

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Hello, new to these forums, but I received my BLF-A6 from Banggood a couple days ago and the flashlight would not turn on. The batteries are good and I can turn the flashlight on by completing the circuit by linking the battery to the frame with the tailcap portion removed. Also the flashlight can sometime be activated by having the tail-cap sit on top of the threads. Any tips on how this can be fixed, or should I return the flashlight to Banggood or contact the manufacturer. Thanks.

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Likely the switch retainer is loose and not properly engaging the switch pcb to the tail cap. Use some needle nose pliers to tighten it. Better yet, remove the brass ring and pcb and clean them and the tail threads first with alcohol and a paper towel as there are often metal shavings or other detritus that interferes with proper threading. Then relube them and reassemble.

Edit- BTW, welcome to the forum, we fix stuff or make it better.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

Meyer
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See first post – “Some flashlight basics:” to locate the error (e.g. battery tube, tailcap switchboard, switch, retaining ring …).

Mine had a too short battery tube which couldn’t get contact with the “outer area” of the tailcap. Banggood sent me a new battery tube so i could remove the workaround.

1dash1
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Rufusbduck wrote:
The A-6 is an ideal light for candle mode operation so if there’s a diffuser that fits with the head removed could someone mention it so it can be listed in the op?

Both the 20-24mm and the 20-25mm fit the A6:
https://www.fasttech.com/p/1347102
https://www.fasttech.com/p/1140010

I like using these wand-type diffusers when walking along side the road. It shines like a lantern, so it is very visible to oncoming traffic from hundreds of yards away.

P.S. I do not remove the head when adding the diffuser. Works just fine that way. Besides, with the BLF A6, I’m worried about decapitating the LED whenever I unscrew the head.

Rule 1-1 as it applies to life, take it as it comes.

hank
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If you remove the head, what keeps the LED board in thermal contact with the body of the light?
I thought pressure from bezel-lens-reflector-spacer held it down.

Retriever222
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Yep, tried that, but it was was as far as it could go, I took the tail cap portion apart and put some rubbing alcohol on all of the parts, but the problem still persists.

Edit, paper clip text did not work the first time, but it did work the second time, except when I shake the flashlight, the light turns on.

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