SureFire L1 tailcap disassembly procedure - changing resistance values

Blindasabat

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I finally got a Hakko soldering iron (for Christmas) and replaced the resistors in three L1 tailcaps tonight. I repaired a 100 ohm I put in a while ago, then replaced two others. One with a 20 and another with two 100 ohm resistors in parallel for a resulting 50 ohm tailcap. I am using these on Malkoff M60W, three direct drive K2 modded L1 heads, a Milky 900mA 1st gen KL1, a 2nd gen KL1, an SOB1000 modded KX1, and a Cree L1. I discovered the tailcap of the Milky KL1 had already been modified to 30 ohms. Nice. Now I don't even have a stock 10 ohm tailcap anymore, just 20, 30, 50, and 100 ohms. <<Edit - oops, I found another 10 ohm tail cap>>
I have discovered that the trick to getting these tailcaps open for modding is to
1) Unscrew the ring around the rubber boot
2) Pull off the boot revealing the head of a plastic pin that holds the switch into the aluminum housing
3) Take two flat screwdrivers or other prybar shaped tools and pry two opposite sides of the head of the plastic pin upward at the same time. If you pry only one side, you will break the head off the pin. You will get the switch out, but will have to either glue the head back on or bore it out for a screw like Milky did.
4) Then the switch 'guts' will fall out the other side.
5) Take one of your small regular screwdrivers and pry off the plastic housing opposite of the coil spring. The housing is held on by three pins. Try not to break these either.
6) You will see the resistor soldered to the board. Desolder it and replace with the desired resistor.
7) push it all back together the way you took it apart.

The 'trick was in step Three: using the two small screwdrivers to pop out the plastic pin without breaking it. It takes breaking one to learn how they are put together.
 
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Blindasabat

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I found an odd behavior of the Cree L1 short body with the 50 ohm tail cap. When I press on to low, release, then press on to low again immediately, the second press gives me half the lumens of the first press. This is very repeatable. If I wait a few seconds after one press, the next press is the higher low level. I in effect now have a three level L1, but two levels are both very low.

... replaced the resistors in three L1 tailcaps tonight. ... Now I don't even have a stock 10 ohm tailcap anymore, just 20, 30, 50, and 100 ohms.
 
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Kestrel

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Blindasabat, this is great info - this is the first time that a SureFire L1/L2 tailcap disassembly procedure has been posted here AFAIK. I have created a new thread from your two posts above for easier reference.

Furthermore, your reports about a possible lower-low in the latest 'Cree' generation of L1's is very interesting and I think that many folks might want to experiment with this.

I've also taken the liberty of reposting part of your PM regarding my inquiry re: outputs, if that's OK:
Blindasabat said:
With a 20 ohm resistor in place of the stock 10 ohm, the low drops only slightly lower judging by sight. The 30 is a decent drop, maybe to about 5L. The 50 ohm starts to get down to about 2-3L and about 1-1.5L for 100ohm. The 50ohm actually has about a 1/2L low-low and the 100 ohm resistor has a stoopid low-low similar to the HDS lowest or Quark moon mode of 0.05 or something like that. The second low levels are only on the last generation Cree L1. I tried both 50 and 100 ohm tailcaps on a 1st/2nd gen 4-flats long body and saw no second low level.

Thanks for posting this, I for one will definitely be looking into this further. :)
Kestrel
 

Kestrel

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Another interesting aspect of this is that many folks have tried 3.7v rechargeables in their 'Cree' L1's (I've tested this as well), it seems like the existing driver is reasonably tolerant of the higher voltage. One reason I haven't been interested in going this route until now is that the ~10+ lumen 'low' of the latest L1 version is already too high IMO, and going to 3.7Vin makes it substantially brighter that that. I'm guessing that getting back to a decent 'low' while using 3.7v cells would be desirable for some here.

If you have any IMR123's, would you be able to give an idea of some of the new 'low' outputs using the higher voltage cell and the higher resistance tailcaps?
 
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Blindasabat

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With a 20 ohm resistor in place of the stock 10 ohm, the low drops only slightly lower judging by sight. The 30 ohm TC has a decent drop, maybe to about half, or about 5L. The 50 ohm starts to get down to about 2-3L and about 1-1.5L for 100ohm. Regarding the 3rd "low-low" levels: The 50ohm actually has about a 0.5L low-low and the 100 ohm resistor has a super low-low similar to the HDS lowest or Quark moon mode of 0.05 or something like that. This is all with a primary CR123. I will have to try an RCR123 later.

So: ohm, 2nd level, 3rd level
50 ohm - - 2-3L - - - 0.5L
100 ohm - 1-1.5L - - 0.05ish

All lumens are educated guesses at the moment.

The 20 & 30 ohm tailcaps have no discernible 3rd level. They are likely just so close to the 2nd level that I can't see any difference.

The second low levels are only on the last generation Cree L1. I tried both 50 and 100 ohm tailcaps on a 1st/2nd gen 4-flats long body and saw no second low level.

Kestrel, I have an IMR123 somewhere, but can't figure out where it is at the moment. I also have seen the $16 light meter from the $20 light box thread, so I may pick one up.
 
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Blindasabat

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Found my IMR123. All low levels seem to be double what they were on a primary. The 100 ohm low-low is still very very low.
 

kd5bwt

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Replying to this long-dead thread to thank @Blindasabat for the good disassembly instructions. I have an A2 Aviator with a failed tailcap and this was very helpful in taking it apart. My tailcap broke in the standard manner and I may or may not fix it, but it was a fun journey.

IMG_9607.jpg
IMG_9609_v2.jpg
 
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