M3LT problems

tundratrader

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Oct 31, 2008
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272
Location
Homer, Alaska
Hey guys long time no check in. Here is my issue.

I have noticed mine has started to flicker/ultra strobe on high output mode. This is a standard M3LT not M3LT-S. It is hard to repeat but it mostly happens during initial transition from low to high. I just changed my batteries with fresh 3.25 volt SF cells and it is still flickering. The batteries that were in the light were only down to about 3.05. I dont have any 17500 cells to try it out. The problem is intermittent at this point.

I have also noticed that I am getting the occasional high pitched scream from the tailcap.

No issues otherwise but these are major to me. The light has worked flawless until now. I have probably ran a 12 pack and a half through the light.

Thanks for any suggestions. I will call Surefire on Monday regardless.

Zach
 

chai

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Mar 4, 2010
Messages
24
I would just give surefire a call they will try to diagnose it over the phone having you do some simple testing. But you would most likely have to send it in since the problem happens occasionally. My guess would be it has a faulty switch.
When i first got my M3LT it wouldn't turn on in high mode maybe once in every 7 to 10 presses even with the tailcap tighten all the way it wouldn't go in to high. Sent it in and it came back with the same head+body serial numbers. I think they change out the tailcap on mine.

Good luck, but you don't need it there nothing to worry about you bought a surefire and they'll back there product.

This is one awesome flashlight so far no other problems since i got mine back.
 

tundratrader

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Oct 31, 2008
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272
Location
Homer, Alaska
So the light has been sent to Surefire. They claim this is the first they have heard of any tailcap issues. Not worried I know they will sort it out. I have never been a fan of multiple mode lights. I refuse to carry them for Fire or EMS. I love the throw and light this thing puts out but I really need high only. I have been very impressed with the usability of low but I would prefer high only. This isnt really a stroll around jogging light to begin with and battery life is not an issue for me.

Is there a reason besides so few of these in the hands of people that someone hasnt figured out a resistor or whatever needs to happen in the tailcap to give it high only? I am sure one of you is up to the task!! I want a clicky and high only!!!!

Zach
 

angelofwar

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Nov 17, 2007
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3,336
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South Carolina
As far as your last post, this would be an easy fix if the M3LT tail cap wasn't longer. On an M6/M3 it only comes on low, so that tells me that it's not a resistor in the tail cap, but some kind of booster (words escape me right now), that allows more volts/amps to get to the head. However, with the M3LTS, it will still do the high on strobe, telling that the electronics that control the strobe (and not the high only) are in the head. The M3 T/C seems rather easy to take apart from the top, but, being limited on funds, I'm not willing to take mine apart...but hope this gives you some insight as to how to get a high only????
 

turboBB

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Jan 16, 2008
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1,032
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NJ, USA
@Zach: I've reposted the oil smudge as well as the service issues I encountered after sending my M3LT back to SF to the end of my review. Please let me know how your light turns out (better than mine I hope).

@AOW: In taking current draw reading, it was interesting to note that (and just guessing here) the internal resistance from the meter caused the M3LT to come on in high so the electronics that controls levels is definitely in the head and not the TC.
 

tundratrader

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Oct 31, 2008
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272
Location
Homer, Alaska
I will keep this thread updated with my service. They said between 1-2 weeks for turn around. I guess they dont inform you when it is on its way back either. I guess it will be a nice surprise when it gets back.
 

sfleduser

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Joined
Nov 25, 2012
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2
Hello,

I am resurrecting this rather old thread because I am having the same issue.

I have a surefire m3lt-s, and from day one it has flickered after initial use on fresh batteries.

What I mean is this: if I put in fresh batteries, it works fine. However, as I use that set of batteries, instead of slowly dimming over time as they run out (as all LED flashlights do) the light just begins flickering - not quite as bad as the actual strobe mode, but close...

What this means is, I can only ever use brand new fresh batteries - after a short period of use (sorry, no figures) the light becomes unusable. It goes from full power to flickering with no period of dimming or diminished output inbetween.

So this is a problem, and not how the light is expected to work ?

Thanks.
 

WarriorOfLight

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Oct 17, 2009
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1,754
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In the middle of Europe
I'd contact the SF support after checking that the contacts are clean. You should also use quality cells since the current draw on high should be >1A and cheap cells may make problems.
 

sfleduser

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Nov 25, 2012
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I'd contact the SF support after checking that the contacts are clean. You should also use quality cells since the current draw on high should be >1A and cheap cells may make problems.

I have never used anything but the surefire branded batteries...

Ok, I will send it in.
 

SeaGoat

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Joined
Jun 20, 2012
Messages
5
I am also having the same issues with my M3LTS!
Please do give us an update when your diagnoses is complete!

This is starting to make me regret not buying the M6LT instead...
 

SeaGoat

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Joined
Jun 20, 2012
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5
OK just got off the phone with Surfire CS.
We did the jumper wire test, with NEW batteries and the light turned on in a lower mode.
The tech said the light should have came on in the HIGH mode, and the light should be returned for inspection.

I'm sort of confused as Ive read somewhere that the light should come on in the low mode when using a jumper!?!

Can anyone confirm this one way or the other!?! My thanks in advance !!!
 

enomosiki

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Joined
Mar 13, 2011
Messages
1,109
Surefire two-stage tailcaps contain resistors inside. Pressing the switch lightly will make the resistors limit the current flow, while pressing it hard will bypass the resistors and allow all available current to be delivered.

By using a wire to connect the batteries to the tube, you are effectively bypassing the resistors and allowing all current to flow freely, hence why the light should be giving maximum output.

So, yes, your light is funky. Get a RMA and send it in and they will tell you the same thing and will fix it or send you a new one.
 

LowFlux

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Joined
Aug 6, 2008
Messages
210
A bit off topic here, but has anyone been getting problems with RMA? I sent them an email twice in the last month and got no response from Surefire.
Surefire does not have an email or online presence. Give them a call
 

forstersun

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Joined
Oct 9, 2013
Messages
73
Location
Guangzhou, China
I got the same issue this afternoon, mine is a m3lt-s, never used 17500.
Exactly the same as yours, flicker at very high speed on high output mode, triple faster than strobe mode,maybe?
Now I'm just waiting a friend of mine bring me his tail and test it on mine.
 

forstersun

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Joined
Oct 9, 2013
Messages
73
Location
Guangzhou, China
my problem was solved this morning. Tail cap is ok, it was a battery problem.


I repalced the tail cap with my friend's, it still flicker. I thought must be something wrong with the kx9t-s, which nothing i can do.
I just kept the high output mode on and wanna see what will happen later.
Flicker frequency was slower as time went by, so did the luminance.
After about 30-40min, I took out the batteries, found that one of them was hotter then the other two, which means the hotter one got greater internal resistance. I measured the voltage with a multimeter, the hotter one got lower voltage.
I just replaced the batteries, done.
They were all new betterys, how could that happen....
 
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