Fenix LD01 SS "Jumping" Problem -- SOLVED!

AA6TZ

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Those of you who own Fenix LD01_SS flashlights know first-hand what great little keychain utility lights they are.

Since they were purchased new in November, both of my LD01 SS's have operated smoothly and without the "jumping" problem experienced by several CPF'ers. That is, until yesterday...:mecry:

After thinking about what might be the underlying cause of the lights suddenly acting-up after having been problem-free for the past two months, it dawned on me that it just might be a mechanical problem. Okay, not exclusively mechanical per se, but an electrical problem caused by mechanical motion/movement.

The LD01, for all intents and purposes, is divided into two "almost equal" sections, joined together by a quarter-inch of fine-to-medium threads and separated/spaced by a small rubber o-ring. If, instead, the torch were to have been re-designed such that a much shorter top section were to be implemented (measuring 5/8" from the top, ending at a point directly beneath the knurling) to control its On/Off switching, any resulting torsional forces placed upon the AAA battery would thus have been eliminated.

Please allow me to explain . . .

Each time the flashlight is cycled through/between its On and Off positions, a small torsional (twisting) force is exerted on the AAA battery and on both the LD01's upper (positive) and the lower (negative) contacts. Continuity between the AAA-cell's terminals and the flashlight's contacts can be briefly interrupted by the battery turning or shifting just a tiny fraction of an inch . . . which is likely what occurs when the threads are loose (too much play) and/or a sufficient amount of oxidation has formed on the contacts (and on the battery's terminals, too!).

What to do?

First, I applied DeoxIT (via Q-Tip) to the LD01's positive and negative contacts, being careful not to slop any of it along the inside of the tube leading down to the negative (spring) contact. The DeoxIT serves to keep the contact surfaces "wetted" (providing greater, more consistent and longer lasting conductivity).

Next, I performed the same operation on a fresh Duracell AAA battery, having first rubbed both of its terminals on a clean T-shirt in an effort to rid them of oxides and stearates (the latter is the "oil" left by human fingers...as in fingerprints).

Finally, I liberally coated the bottom section's threads with Nyogel_760G in order to minimize the gap between mating threads, thereby reducing the mechanical play introduced by operating the flashlight.

Guess what? It WORKED!!! There has not been one single occurrence of "jumping" observed yet ... and I've been fiddling with the light for hours. The beam is strong and steadfast as hell and the LD01 even feels more robust, too -- undoubtedly due to the tighter thread tolerances created by the extra-thick application of NyoGel.

Normally, I apply only a thin film of NyoGel to the threads of my torches ... but the LD01 clearly LOVES a heavy coat of the stuff! :D

So . . . before you send your LD01 in for repair or exchange, please try my 2-minute service routine first and see if it doesn't cure YOUR LD01's jumping problem, too. :thumbsup:

Cheers! :twothumbs

Best Regards,

-Clive
 
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applevision

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Thanks Clive.

This is really smart and "feels" right.

I think you got it and will have made a lot of unhappy folks happy! :thumbsup:
 

EngrPaul

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I noticed the bottom edge of the head of my LD01 is touching the battery tube when it's switched on.

If the PCB moves up any further into the head, the top of the battery tube won't be hitting it anymore.

This would be something else to check. Intermittent contact with the PCB could happen if there is no travel left due to bottoming out on the body. Lubing/conditioning might help for a while.
 

rockz4532

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Thanks for the tips, but sadly, all i knew to do was clean the threads and contacts, and lube the light. I thus sent it to 4sevens for replacement, but i must say A+ to 4sevens customer service!
 

AA6TZ

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I noticed the bottom edge of the head of my LD01 is touching the battery tube when it's switched on.

If the PCB moves up any further into the head, the top of the battery tube won't be hitting it anymore.

This would be something else to check. Intermittent contact with the PCB could happen if there is no travel left due to bottoming out on the body. Lubing/conditioning might help for a while.

Hello Paul -- Interesting observation. I'm not exactly clear what you meant by "the bottom edge of the head of my LD01 is touching the battery tube when it's switched on" comment. It's true that the copper trace in the center of the PCB makes contact with the anode of the battery when the light is switched (er turned) on -- and I think that's what you meant..:thinking: One could only hope that the LD01's designers would have factored in the forces that could be exerted upon the PCB by the battery and chosen the appropriate value of spring constant for the lower contact. But ya' never know . . . :rolleyes:

Please excuse my ignorance if I miscontrued your comments in any way.:eek:
It should be painfully obvious by now . . . :stupid:
Thanks a lot for your reply. :twothumbs

-Clive
 

AMD64Blondie

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From the title I thought you were having problems with the light literally jumping out of your pocket... (That made me think "Huh? Wait,what the heck...")
 

EngrPaul

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Hi Clive,

I'm suggesting if the body makes contact first (RED arrows), then the (-) connection from the tube may not make proper contact (GREEN arrows)

IMG_2738.jpg


IMG_2740.jpg
 

AA6TZ

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Encinitas, CA
Thanks for the tips, but sadly, all i knew to do was clean the threads and contacts, and lube the light. I thus sent it to 4sevens for replacement, but i must say A+ to 4sevens customer service!

Hi Rockz4532 -- You pretty much DID everything that I outlined, spare the DeOxIT spritz (which can make the difference :eek:).

4sevens gets nothing but the very best reviews on CPF - and it's becoming clearer and clearer why! :thumbsup: I'm happy to hear that you got your malfunctioning LD01 SS replaced . . . 'cuz it's just too darned useful (and fun) of a torch to be without!!! :D

Take care.

-Clive
 

AA6TZ

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Hi Clive,

I'm suggesting if the body makes contact first (RED arrows), then the (-) connection from the tube may not make proper contact (GREEN arrows).

Paul -- Thanks for the clarification. :thumbsup: (BTW - That was my second guess...:whistle:)

You're absolutely spot-on. That certainly would present problems down the line (major problems). Now you've got me worrying...:eek:

BTW - Is the material (aluminum vs. stainless steel) the only difference between our cases?
Thanks a lot for your responses. :goodjob: :thanks:
-Clive
 

EngrPaul

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BTW - Is the material (aluminum vs. stainless steel) the only difference between our cases?

-Clive

That, and anodizing (which is an insulator)... :sssh:
 
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