# Burnt A2 driver



## ma tumba (Aug 21, 2016)

Today the driver in one of my A2s died with a buzz sound. The guts now smell burnt. The light had a strion lamp, a calipso ring and ran off 2x aw imr 16350 (not fresh off cherger). I had used this setup for years. 

Has anyone ever been able to kill his a2 like this?


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## Repsol600rr (Aug 21, 2016)

Can I just be the first to say that sucks. Haven't fried my user but I've only ever run primaries through it.


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## Illum (Aug 21, 2016)

I don't actually recall anyone on the forum killing an A2 in this way. I don't recall people killing A2s in general. The limitation of using CR123A only probably made the A2 operate only sporadically. I know when I carried it about 70% of the time the LEDs is enough. In the modern day 1000 lumen LED era, I still carry an A2-HA-RD when I'm outdoors. If I run into something that needs more light then I have a dedomed CREE XP-L Eagletac P200LC2 set on high, but most of the time the A2 will work. Plus its full spectrum XD.


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## m4a1usr (Aug 21, 2016)

Ooch! Sorry to hear that. I have never ran any of my A2's in a double rechargeable cell configuration but seem to remember a comment about the buzzing you mentioned in one of the links in the CPF A2 information thread. I'm sure you already have it bookmarked. What I can offer is my experience with Surefire regarding repair/replacement of the older A2's. A couple years ago I bought a burned out driver A2 body (from Eric) and decided to send it back for warranty work. It has to go back as a complete light. Parts alone will not be honored. They sent me back a new A2 LED version. Not a horrible problem to get the newer version but it is not the same as the incandescent version and now limits what can be done with the light.

On the other hand you now have a good candidate for lego'n to a morphed A2. There are many configuration/ direction choices you can go. Mine has a LF E2C with a sweet triple behind a Z44. A little creativity and nothing is off limits.


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## ma tumba (Aug 22, 2016)

I appreciate your condolences, gentlemen!

I was under the impression that the 2xRCR123 option had been discussed so many times and had eventually been confirmed. Actually, my own experience had been quite positive for years. But as usual, you have a positive experience just until the disaster happens and then what you are left with is the negative experience.

Anyway, I was sane enough to keep my "spare" 4 flat version on the primaries, so I still have a working A2. 

And yes, the fried light is still a nice body which is most likely to go now to Tana for his mod. I have had his TripLED, SingLED mods and they are awesome. 

Need to get more stock A2s though. It is ridiculous that guys have to pile great pieces of older technologies just because there is now more parts for repair. I have to keep a number of "spare" great LaserDisk players, a number of "spare" great video processors, as well as spare incand bulbs and other incand related stuff. Thats really annoying.


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## Repsol600rr (Aug 22, 2016)

I know what you are saying. That's why I have 3 a2's and wouldent mind some more. It' may be old tech but it's not irrelevant. Just Becuase it's been surpassed doesn't mean it doesn't do it's original intended function brilliantly. And I'm very happy with it's performance. Find a few more and keep a stockpile. I want mine running well into the future.


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## Tana (Aug 22, 2016)

Just tried removing brand new stock A2 driver from the body and - fail... it came out but all messed up... too much trouble removing that thing with damage, can't imagine how it would be removing it undamaged...


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## ShineOnYouCrazyDiamond (Aug 22, 2016)

Bummer to hear your A2 let it's magic smoke out. I've run every A2 I've ever had on 2 x RCR123 cells and never had a single issue - albeit with modded rings that can handle the extra voltage. 

A2s have been popping up quite frequently lately in the marketplace threads. Grab another spare when you can. I recently picked up a spare A2 and I feel the price was very fair in the $100-$125 range for excellent condition.


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## Illum (Aug 22, 2016)

if they can still go for $125 today it means it retains value very well... because when I started carrying the A2 it was 2004? and at that time mine were bought second hand around that price. I prefer they come used, dinged up so I don't have to make the first scratch


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## scout24 (Aug 23, 2016)

I recently picked up a 4 flats, and am glad I did. My Tad bulbs and holder are in the mail which is good. I'll have to pick up a spare at some point, I'm just a sucker for that body style. Tana- sad to hear the drivers are a pain to get out! I was hoping you had some spares around with all the mods recently.


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## Illum (Aug 23, 2016)

Err scout24, just a heads up the lamp pitch changed when surefire went from the squared to round. the lamps are NOT interchangeable even though they are both designated MA02. If you happen to blow the old lamp, your only options are either tracking down a FM strion adapter or order a lumen factory HO-A2 lamp. Most MA02 Surefire replacement lamps still in the market will not work for the square model. Learned this the hard way


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## ShineOnYouCrazyDiamond (Aug 24, 2016)

Illum - check out Tad's Customs new bi-pin adapter for the A2. Readily available and works with the square A2.


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## scout24 (Aug 24, 2016)

Illum- Thanks for the heads up. I've never held on to an A2 long enough to have bulb fitment issues beyond the occasional Lumensfactory being cranky in the 4 flats body style. I hope the Tad Customs is without issue. Strange that factory bulbs fave you trouble. You would think SF would have made a design change like the older color-coded bulbs going to the model number printed on them like the MN series.


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## ShineOnYouCrazyDiamond (Aug 26, 2016)

There's a nice A2 up for sale in the WTS for $110 right now.


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## ampdude (Aug 27, 2016)

scout24 said:


> Illum- Thanks for the heads up. I've never held on to an A2 long enough to have bulb fitment issues beyond the occasional Lumensfactory being cranky in the 4 flats body style. I hope the Tad Customs is without issue. Strange that factory bulbs fave you trouble. You would think SF would have made a design change like the older color-coded bulbs going to the model number printed on them like the MN series.



It is absolutely true, and that is why I hate to use Lumens Factory bulbs in round body A2's. They press down too hard because they were made to the square body specs. I've put a factory bulb in a round body A2 that I was running a Lumens Factory bulb in for awhile and it no longer worked with factory bulbs because I was using the Lumens Factory version for awhile tightened down like I do with the normal factory bulbs. So you have to keep that in mind when using them with a round body, don't tighten them down very much. Lumens Factory should be making two different versions IMO.


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## Repsol600rr (Aug 27, 2016)

I personally slightly filed down the lumens factory bulbs. Not a lot but a bit. Also I have found that If the contact does get pressed too far you can very very gently pry the contact in the a2 body with the tip of a knife so that it makes contact again with the stock bulb. Didn't even seem like it moved up when I did it so it was very close already. Do these things at your own risk. I was very careful but I can imagine messing either of these procedures up would cause an issue. Soon I will order the tad customs kit and put that in my user but as it sits I have the lf bulbs for the user and ma02s in the bedside and spare.


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## ma tumba (Aug 28, 2016)

I wonder if anyone knows how the A2 circuit is switched as the tail cap progresses from the full off to the LED+bulb on? 

What I have in mind is this: is it possible to replace the driver by a piece of wire or whatever so that the bulb is switched on direct drive when the tail cap goes from half way to all the way down?

In that case there is a lot of high power 6-7V bulbs that could be tried in Tad's socket off 2 IMR 16350. As well as 3.7V bulbs off 1x17670. And it would still be a 2 beam light, which is the core advantage of A2.


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## Illum (Aug 28, 2016)

the A2 tail has leaf springs on the sides with a PCB under the rubber boot. the PCB only has one component on it: a 1/4W 5% 10ohm resistor. When the tailcap is slightly depressed, the leaf springs contact the body tying the 10R in line with the circuit and turning on the LED. Fully depress the boot causes the leafsprings to flatten and shorting out the resistor, turning on the incandescent. Somewhere in the driver it senses battery impedance [or conductance?] and references it against a known measure. Below it and the PWM-fed Willie circuit is disabled and the LEDs operate direct drive. Above it the PWM incan circuit turns on, LED still in direct drive. 

Unfortunately, the Tailcap is a two piece assembly that is downright impossible to take apart and reassemble [glued in mating surfaces].


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## ma tumba (Aug 29, 2016)

Illum said:


> the A2 tail has leaf springs on the sides with a PCB under the rubber boot. the PCB only has one component on it: a 1/4W 5% 10ohm resistor. When the tailcap is slightly depressed, the leaf springs contact the body tying the 10R in line with the circuit and turning on the LED. Fully depress the boot causes the leafsprings to flatten and shorting out the resistor, turning on the incandescent. Somewhere in the driver it senses battery impedance [or conductance?] and references it against a known measure. Below it and the PWM-fed Willie circuit is disabled and the LEDs operate direct drive. Above it the PWM incan circuit turns on, LED still in direct drive.
> 
> Unfortunately, the Tailcap is a two piece assembly that is downright impossible to take apart and reassemble [glued in mating surfaces].



Thanks for the information! Now I understand why the voltage defferences are "almost" identical everywhere regardless of the position of the switch. And it also explains why the LED part actually has 2 levels: the "higher" level corresponds to the shorted resistor. It is pretty noticeable BTW despite the tiny change in voltage.


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## Tana (Aug 29, 2016)

Illum said:


> the A2 tail has leaf springs on the sides with a PCB under the rubber boot. the PCB only has one component on it: a 1/4W 5% 10ohm resistor. When the tailcap is slightly depressed, the leaf springs contact the body tying the 10R in line with the circuit and turning on the LED. Fully depress the boot causes the leafsprings to flatten and shorting out the resistor, turning on the incandescent. Somewhere in the driver it senses battery impedance [or conductance?] and references it against a known measure. Below it and the PWM-fed Willie circuit is disabled and the LEDs operate direct drive. Above it the PWM incan circuit turns on, LED still in direct drive.
> 
> Unfortunately, the Tailcap is a two piece assembly that is downright impossible to take apart and reassemble [glued in mating surfaces].



Actually it's quite doable, requires amateur skill level I'd say... also, L1, L2, A2, etc - all those tailcaps have same guts...

I don't want to copy my whole L-series and A-series modding thread but below photos show some details for sharp eye...


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## Illum (Aug 29, 2016)

you sir are my hero. 


I bandsawed off "the hat" under the boot to take apart my tailcap. There was a time when my A2's tailcap inexplicably stopped working [screw it all the way in and the incandescent won't light, but swapping the TC from another A2 it worked just fine]. Surefire replaced it for free, just sent me out a new Tailcap. I was curious on whats inside it, so I didn't expect to see it through reassembly.

Also, if anyone is tech savvy enough to want to understand the A2 driver, Willie Hunt has a webpage for something similar, called the LVR [Lightbulb voltage regulator] 
http://www.cs.indiana.edu/~willie/lvr.html
The schematics is listed under documentation.


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## ma tumba (Aug 30, 2016)

Tarik, thanks for the picrures, I think that most likely this dead A2 isgoing to you for the quad mod.

Sean, thanks for the heads up re that a2, I think I've missed it but hopefully I am getting that NIB A2 that just appeared in the WTS section.


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## ma tumba (Jun 26, 2017)

Keep frying my A2s.. this time I was able to fry a Koala led ring. Not sure what exactly happened and why. I installed 3x yuji leds and the light worked great until after I tried another set of leds (not the second set but rather 10th one) when the leds would not light up and some smoky smell comes out of the light. The bulb works great and the replacement Koala ring has worked well so far since then


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## Illum (Jun 28, 2017)

Probably from overheating, though I'm surprised it failed this way. In addition to the LED driver component, Koala's driver also has an integral LDO that drops about 0.29v at 150mA. Most LDOs have a thermal shutdown feature but I'm guessing something else on the PCB plane may have failed. Have you tried installing new LEDs to see if the failure was actually the driver and not the LEDs?


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## Tana (Jun 29, 2017)

ma tumba said:


> Keep frying my A2s.. this time I was able to fry a Koala led ring. Not sure what exactly happened and why. I installed 3x yuji leds and the light worked great until after I tried another set of leds (not the second set but rather 10th one) when the leds would not light up and some smoky smell comes out of the light. The bulb works great and the replacement Koala ring has worked well so far since then



Oh, man... more and more A2 bodies that can now be bored to fit 18650 cells...


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