# SureFire U2A (SSC P4 version) disassembled



## Justin Case (Jan 20, 2010)

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## Black Rose (Jan 20, 2010)

How does the new LED look, beamshot-wise?

Was it worth swapping out the SSC?


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## csshih (Jan 20, 2010)

cool pics of the driver, can't say I've ever seen that before.

what gives the selection ring tactile feel?


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## 65535 (Jan 20, 2010)

If by tactile you mean the resistance it's just an O-ring providing friction, there are no stops or clicks on it.


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## csshih (Jan 20, 2010)

doh. I feel stupid now. I thought U2s had some sort of clicks.


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## maxspeeds (Jan 21, 2010)

Glad you got her apart, Justin! Great Mod. :twothumbs

@csshih, U2 rotates smoothly until it hits a machined stop. The Kroma has clicks via a fragile plastic ring.


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## Justin Case (Jan 21, 2010)

csshih said:


> cool pics of the driver, can't say I've ever seen that before.



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## Justin Case (Jan 21, 2010)

Black Rose said:


> How does the new LED look, beamshot-wise?
> 
> Was it worth swapping out the SSC?


 
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## Justin Case (Jan 22, 2010)

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## ideefixe (Jan 22, 2010)

Great photos! Just a quick question: is the removal of the selector ring necessary for an emitter swap? It looks like the bezel portion of the head can be twisted off and the emitter can be accessed easily. Looks like a great host for a K2 TFFC upgrade.


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## Nitroz (Jan 22, 2010)

csshih said:


> doh. I feel stupid now. I thought U2s had some sort of clicks.



I think it's the Gladius that has a click type feel to the switch.


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## Justin Case (Jan 22, 2010)

ideefixe said:


> Great photos! Just a quick question: is the removal of the selector ring necessary for an emitter swap? It looks like the bezel portion of the head can be twisted off and the emitter can be accessed easily. Looks like a great host for a K2 TFFC upgrade.


 
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## Justin Case (Apr 4, 2010)

Minor update:

I recently tested this XP-G R4 mod'ed U2A with 2xAW16340 fresh off a Pila charger. No apparent problems so far in very brief usage. So the U2A driver may be able to run at 8.4V/7.4V.


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## Greg G (Apr 5, 2010)

I've always been impressed with Surefires electronics. They put a lot of effort into them.

I think your mod is a good one. It's something I would do if a U2 came my way at a decent price.

You have a lot of guts risking blowing the driver with the RCR's. 

Thanks for the thread.


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## Trashman (Apr 5, 2010)

To my eyes, the tint on the XPG modded U2 is much more pleasing.


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## Justin Case (Apr 5, 2010)

Greg G said:


> I've always been impressed with Surefires electronics. They put a lot of effort into them.
> 
> I think your mod is a good one. It's something I would do if a U2 came my way at a decent price.
> 
> ...


 
ptolemy on CPF MP had a couple of recent U2A sales threads at $125 IIRC. Unfortunately, I think he's sold out. But who knows. Maybe he'll get more. Try PMing him.

I give full credit to 325addict on leading the way with using 16340s. He was the first person I saw on CPF to post that he used 2x16340 in a U2A.


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## wquiles (Apr 5, 2010)

Nice build, and thanks much for the photos on the magnetic selector circuitry/board - I always wondered how it looked on the inside :naughty:


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## Greg G (Apr 5, 2010)

Justin Case said:


> ptolemy on CPF MP had a couple of recent U2A sales threads at $125 IIRC. Unfortunately, I think he's sold out. But who knows. Maybe he'll get more. Try PMing him.
> 
> I give full credit to 325addict on leading the way with using 16340s. He was the first person I saw on CPF to post that he used 2x16340 in a U2A.


 



I wonder how the U2A driver would work with 1 x 18650 and a low Vf emitter?

I'm not going to buy one if I can only use 123 primaries. 

Does the battery tube appear to have enough material to bore to 18mm?

Thanks.


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## Justin Case (Apr 5, 2010)

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## Greg G (Apr 5, 2010)

Thanks for the information. I have accumulated quite a few XP-G's for future builds. I'll go through them and see if I have one with a very low Vf and set it aside.


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## Justin Case (Apr 6, 2010)

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## Justin Case (Jan 6, 2012)

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## wquiles (Jan 6, 2012)

Thanks for the update Justin - great thread, and thanks again for the photos


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## tsl (Jan 9, 2012)

Justin Case said:


> I recently re-mod'ed this U2A by installing a neutral tint XM-L T5 bin LED. As expected, the hot spot lux dropped, although I had hoped for less of a decrease. The lux went from 11,400 with the XP-G R4 to 8200 with the XM-L (basically back to the original value with the Seoul P4). The current draw on 2xAW16340s is about 0.4A, with a total power draw from the batteries on the order of about 3.15W. With the XP-G, the U2A used to draw about 3.3W, so power consumption has dropped by about 5%. The XM-L Vf is about 2.9V (was about 3.1V), giving a driver efficiency in the mid-80% range.



This is one of the few posts where I've read of a U2 modded with an XM-L. How does the beam compare to the stock SSC P4? Any beamshots?


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## Justin Case (Jan 9, 2012)

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## tsl (Jan 9, 2012)

Justin Case said:


> I'll get a beam shot similar to the one in post #8 later. The XM-L beam pattern is very similar to the stock P4 beam. The XM-L hot spot is larger, but both beams have that same smooth blending of the hot spot into the corona. The XM-L also puts out noticeably more light in ceiling bounce vs. the P4.
> 
> If your U2A already has the threadlocker defeated from a previous mod, then this XM-L mod is fairly easy to do if you have the XM-L on an 8mm diam board like the datiLED board. You need to shim up the board about 1.2mm to get the LED die to the same focus height as the P4. The 8mm diam board fits perfectly between the centering ribs of the U2A heat sink. Thermal glue the shimmed board into place, solder the wires, and screw on the top half of the head.



Thanks; will appreciate the beamshots. I was thinking to send it (it's unmodded) to Milky for a neutral XM-L upgrade.


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## SCblur (Jan 12, 2012)

How many OTF lumens would you estimate you are getting with the neutral XM-L


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## Justin Case (Jan 12, 2012)

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## Justin Case (Jan 13, 2012)

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## Kestrel (Oct 26, 2012)

OK, I've been trying to get my U2 head apart, with no luck so far - this particular SF is one of the *HARD* ones. 

I just bought a pair of small but good strap wrenches of approximately the correct size, but I want to get the plastic control ring off the head assembly because I don't want to destroy it while I'm 'cracking' the head.

I can see how the control ring is retained by the steel clip, how to I get around that to take the plastic ring off? :thinking: It looks like I just turn the bejeezus out of it like in this video - why doesn't the 'stop' for the plastic ring get destroyed?


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## koala (Oct 26, 2012)

Here try this guide by yclo http://www.candlepowerforums.com/vb/showthread.php?192035-Kroma-take-that-liquid-weld!
Read post #6, Kroma disassembly is similar to U2. I have done many.

Some people on youtube rip it off by force, dont do that, you will destroy the groove that holds the retainer ring and your control ring will fall off easily.


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