Fenix LD01 stainless won't turn off

I have a Fenix LD01 Stainless R5 that broke a while back. It won't turn off. As soon as the battery makes contact with the head, it turns on and stays on even when it's fully screwed on. I tried some contact cleaner (DeOxit), and then it worked correctly for a day or two. Then back to never turning off. Unfortunately it's out of warranty.

Anyone know how the switches work, and how to possibly fix it?

Some more info, I just got another, but it's an R4 not an R5. Got it cheap. Swap bodies, I get the same results. Monkey around a bit, if I can touch the positive terminal to the light without much head to body contact, it won't turn on. As soon as there is good head to body contact, it turns on and stays on.

Gator762 said:

I have a Fenix LD01 Stainless R5 that broke a while back. It won't turn off. As soon as the battery makes contact with the head, it turns on and stays on even when it's fully screwed on.

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I don't understand the situation as you described it. My stainless steel Fenix LD01 turns on, as it should, when the head is fully screwed on.

When the head is NOT fully screwed the light turns off.

Check for any tiny, barely visible, metal whiskers near the threads and circuit board which may be causing the problem.

It's junk. Send it to me.

Do check for stray bits of metal contacting the negative ring of the circuit and the body.

If the light turns on the moment the body touches the head with the battery in. Here is your potential problem. Get a digital meter and set it for continuity test. You may need one with a thin a sharp probe since the area is tight. Tap one probe to the side of the head. With the other probe, look inside the head for the circuit board. You will see the round copper pad in the middle, surround by a copper ring. The middle copper pad is the positive contact and the outside copper ring is the negative contact. Tab the second probe on the outside copper ring. Be careful not to lean your 2nd probe to the side, touching the side of the head. If you get continuity, that's your problem. You have a short between the copper ring and the head. Thus when you put a battery in the tube, the moment you start screwing the body on and it touches the head and the head is somehow shorted to the negative copper ring, the light turns on, and remains on, regardless if you tighten or not. If shorted, clean the connecting area between the circuit board and the head using circuit board cleaning agent. Not sure if alcohol will damage the circuit board. Someone else can chip in on how to clean. Then retest/clean until you don't get connectivity between the copper ring and the side of the head.

My LD01 does that with some batteries. Try a shorter battery. As Parnass said, screw the head tight to turn it on, loosen it to turn it off. You might also look for a stretched spring....