# TK40 experience (sad ending)



## tk40 (Dec 18, 2009)

I'd like to add my experience to the pool.
From amazon in early september I recieved a brand new TK40 which served me well till this morning. I took this light on trips far and beyond. From woods in long island to zombie infested pittsburg and it never let me down. Today was different.

I retrieved the TK40 from its resting place, screwed it tight, put my batteries in, and checked to see if everything was in order. Tonight I had plans to walk to Christiana Mall in Delaware after crossing a barren dark field infested with pools of water. I switched the TK40 on, pointed it at a wall and noticed a dimmer than dim spot. Surprised. Clicked a few times to change settings. No change. I then pointed the light at myself and what do I see? Of the 4 LEDs, one is out. Like really out, no sign of life. The remaining three, are flickering, and dim as if they are dying. Puzzled.

I take the batteries out, and pop them one by one into my Nitecore DI. They are all fine. NDI shines brightly. SAD FACE.

I then emailed Amazon, got a reply in 15 minutes saying sorry they can't help. But here's the contact info for 4Sevens and they might resolve the problem.

So here I am with my trusted flashlight which is obviously wounded for unknown reasons, and I am hoping for a replacement or repair. Whichever comes first.

I'm glad everyone else is happier with this light. I was too. 
Hopefully I'll remain a loyal customer to Fenix. I already have two LD20s.


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## John_Galt (Dec 19, 2009)

First, wrong forum...

Second... That sucks. It really does. Not discounting this, but the TK40 has proven to be very durable in extreme conditions.

I could see a few things here...

1) The 4th LED die that does not light up may have a higher forward voltage than the other three. Therefore, if the driver cannot pull enough current and voltage from the batteries, that doe might not light up.
2) What kind of batteries are you using? If they are alkalines, that might explain your problem. As the driver attempts to pull a massive amount of current out of these batteries, the internal resistance will cause the voltage to sag heavily (basically, alkalines do not maintain 1.5v if you are pulling more than a 1-300 milliamps out of them).
Also, if these are batteries you have used before, they might be dead. Just b/c they light up you NDI, doesn't mean they will have enough capacity or voltage to light up a high power light, such as your TK40.
3)The TK40 has a tailcap switch, correct? I am not sure if the tailcap is removeable, if it is, put the batteries in it, and use a piece of wire to short from the negative terminal to the exposed aluminum tube (not the anodizing). If it lights up, the problem is in the switch.

Try new batteries.


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## tk40 (Dec 21, 2009)

John_Galt said:


> First, wrong forum...


I posted my message to the reviews thread but it wasn't (approved?) and hence didn't show up.



> Second... That sucks. It really does. Not discounting this, but the TK40 has proven to be very durable in extreme conditions.
> 
> I could see a few things here...
> 
> 1) The 4th LED die that does not light up may have a higher forward voltage than the other three. Therefore, if the driver cannot pull enough current and voltage from the batteries, that doe might not light up.


With my duracell 2300mAh, I see the 4th LED showing a faint sign of life...but still not bright as others in every mode I tried....


> 2) What kind of batteries are you using? If they are alkalines, that might explain your problem. As the driver attempts to pull a massive amount of current out of these batteries, the internal resistance will cause the voltage to sag heavily (basically, alkalines do not maintain 1.5v if you are pulling more than a 1-300 milliamps out of them).
> Also, if these are batteries you have used before, they might be dead. Just b/c they light up you NDI, doesn't mean they will have enough capacity or voltage to light up a high power light, such as your TK40.


8 fully charged 2000mAh Eneloops.



> 3)The TK40 has a tailcap switch, correct? I am not sure if the tailcap is removeable, if it is, put the batteries in it, and use a piece of wire to short from the negative terminal to the exposed aluminum tube (not the anodizing). If it lights up, the problem is in the switch.
> 
> Try new batteries.


Tailcap experiment failed, and I contacted Amazon to return the item....its been 3 months and they suggested me to contact 4Sevens directly who in turn refused to honor warranties for products purchased through other retailers (Amazon in this case). I conveyed this to Amazon and finally they agreed to send me a replacement. When I have two specimens, I will be in a better position to judge if my LED problem is expected.


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## carrot (Dec 21, 2009)

I find it odd that Amazon told you to contact 4sevens directly about the TK40, seeing as I don't see 4sevens on their seller list?


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## kts (Dec 21, 2009)

Dont feed the troll 

BTW. the trolls dad is ugly


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## DM51 (Dec 22, 2009)

You posted this in the wrong forum, having attempted to post it in an equally inappropriate one. What on earth makes you think your incoherent post is a review, or that it has anything to do with collecting? And what is the relevance of that photo? 

For a new member, this is a sorry start. Your thread does not appear to be genuine. It's closed.


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