Please help...my c2 has a short somewhere.

I have a bored for 18650 cells, Surefire C2 with a Vinh XML drop-in that draws 3 amps (L-M-H) and a McClicky switch. It is my light up the property light. It has never been dropped and is only used when I need to inspect a large area outside (ex. during/after a storm).

I have taken it apart, cleaning the threads, including rewrapping the drop-in, and it is still not working properly. When I turn it on, sometimes it works and sometimes not. If it does not turn on and I bang the head against my hand it will come on. Do you think the drop-in is bad?

It does not seem like the switch.

Thanks for the help everyone.

Sounds like a contact issue ....

How and what do I check?

Well, it's kind of a troubleshooting exercise....

Swap each part with a known good alternative (dropin, battery, tube, switch, etc) and try to isolate the part with the intermittant problem.

Test bypass the switch. Try batteries of slightly different length and/or try a tiny spacer. Try wiggling the dropin, reseating, and/or use a spring washer for better contact.

Etc ...

Is there identical contact, with the wrapping material, between the drop-in and host, now compared to before?

Ii had a similar problem which was effectively battery length, I just pulled the tail spring a little longer, sorted.
There was another time I had a spring on the dropin coming away, needed resoldering, took me a while to notice it ......

I will try all of this and report back. Thanks everyone.

It turns out the pill had loosened from the reflector. I took the light apart to clean and check all of the springs and threads again. When I took out the drop-in to check the aluminum foil wrap, there it was. Thanks for the advice everyone. I would not have thought to check this spot.

Just wondering...what should I do to prevent this from loosening in the future. I tightened it, but I was worried about wrenching on it too hard. Would it be okay to use a bit of thread lock?

If its an issue again, then a tiny tiny blob of thread lock will do the, you will not need much at all to stop a bit of loosening.

Thanks.

Another option besides thread locker / Loctite is clear nail polish.
All sorts of advantages:

• Doesn't need anaerobic conditions to bond
• Easier clean-up during subsequent/future disassembly
• Cheaper - 1 bottle from the Dollar Store for ... wait for it ... $1.
• Lower strength - satisfactory and more convenient for many non-demanding applications.
• Included brush applicator and higher viscosity provides better control during application than the Loctite dropper & runny Loctite.

Clear nail polish has replaced Loctite/Blue for many of things I need it for, and I've been very happy with it.

Thanks Kestrel for the tip. I am going to give that a try.

I'm bringing this thread back to life because I am again having problems with the drop-in. Same drop-in as stated above. This time the led is just barely turning on (less than one lumen).

I have checked to see if it came apart, and it is still very solid. I have pulled the drop-in out and ran it straight from the battery, bypassing the light and switch completely...and it is still only producing a very small amount of light.

Please help!

Definitely seems like an issue with the drop-in itself. I've had a couple over the years fail similarly. Vinh may fix it for you, you should reach out in his subforum or email (easy to find on his forum).

Thanks for the quick reply. I have posted in his subforum.

campingnut said:

I'm bringing this thread back to life because I am again having problems with the drop-in. Same drop-in as stated above. This time the led is just barely turning on (less than one lumen).

I have checked to see if it came apart, and it is still very solid. I have pulled the drop-in out and ran it straight from the battery, bypassing the light and switch completely...and it is still only producing a very small amount of light.

Please help!

Click to expand...

I read a thread in which someone had a contact issue with a Malkoff in a 6p that was innocently bored for 18650. Wonder if that might be an issue here?

There's a currently-active thread here on 'Malkoff dropin connectivity', with the very useful tip of one coil of spring, etc - more info there & highly recommended:

Solution for Malkoff Contact Issues in Surefire 6P's

Two quick notes:

• As the light is bored, does it still have the 'battery shelf'?
• I'm also guessing that the dropin is just slightly too short and the resulting assembled light as no 'Malkoff gap' - I have had the issue that the OP is describing with a non-Malkoff dropin.

I hope the terminology above is sufficient, others can explain with more detail if necessary. Do check out the other thread tho.
Hope this helps,

Kestrel said:

• As the light is bored, does it still have the 'battery shelf'?

Click to expand...

Yes, it has the lip on the inside to hold the cell.

• I'm also guessing that the dropin is just slightly too short and the resulting assembled light as no 'Malkoff gap'

Click to expand...

I have pulled the drop-in out, bypassing the host and running it straight off an 18650 and a wire, with the same issue. Therefore, I am pretty sure it is not a host or contact issue related to the host.