Arc LS: Intermittent/failing switch and repair

I have an Arc LS. Awhile ago, I was using it for some urban exploration, carried in my teeth thanks to the handy rubber-sided switch knob. Unfortunately, the next day the switch refused to work reliably and the following day the light wouldn't turn on at all.

I opened up the switch and saw nothing wrong. Once the switch has been unscrewed from the outside, you can remove the rubber cap to get a white plastic cylinder tapering to a button on one end and a spring on the other. This spring connects the switch electrically to the flat side of the battery. There is another spring mounted on the side of the switch-assembly that connects the switch electrically to the body of the Arc.

I noticed the spring (that connects the switch to the battery) seemed a little tarnished. Sure enough, my multimeter indicated that it had a resistance of between 50 and several megohms. The silver-plated springs in the switch itself had negligible resistance.

Some of the saliva from my mouth had gotten on the spring and corroded it.

I removed the corroded spring from the switch assembly (just pull) and used a file to clean each end of the spring until it was shiny. I re-installed it (push, then use a flathead screwdriver to push it all the way in) and the flashlight works like new.

I learned to avoid Krolls - especially the Arc versions. I went to twisty's and everything's worked fine ever since. I wouldn't even get a Streamlight SL Jr. because they said it uses a Kroll - albeit one that's different from the LS version.

Any non-99cent store push button switch shoud NOT require ANY maintenance or tweaking to work reliably for at least tens of thousands, if not hundreds of thousands of cycles. Say what you will about the Chinese reverse clickie's, but all of mine have worked every time I've pushed them, and I'll take that any time.

Sorry, rant off...

nerdgineer said:

I learned to avoid Krolls - especially the Arc versions. I went to twisty's and everything's worked fine ever since. I wouldn't even get a Streamlight SL Jr. because they said it uses a Kroll - albeit one that's different from the LS version.

Any non-99cent store push button switch shoud NOT require ANY maintenance or tweaking to work reliably for at least tens of thousands, if not hundreds of thousands of cycles. Say what you will about the Chinese reverse clickie's, but all of mine have worked every time I've pushed them, and I'll take that any time.

Sorry, rant off...

Click to expand...

a) the Kroll is very nice for carrying in your teeth!
b) where do I get a twisty?

eric343- congratulations on repairing your Kroll switch!

Unfortunately, the Kroll is prone to flaky operation due to oxidation/fouling on it's contact surfaces. The good news is that it is easily remedied as you have discovered.

For a semi-permanent fix, I can highly recommend the use of a Caig ProGold pen on the springs and contact surfaces of the Kroll switch. It will go a long way towards preventing future oxidation, and in my testing will typically provide a 10% boost in brightness over the untreated switch. Very handy item to have aroud for a variety of electrical uses. The cheapest place I've found them available is at RatShack.

Peter

I had the 2xAA TSP battery holder for the Arc LS. I took out the Kroll (after the 2nd one failed...) and screwed a minimag tail cap into the hole. I press fit a metal plug into the old in the MM tailcap so it protruded enough to make the whole thing into a twisty.

My LS came with a twisty. I think you have to look at the B/S/T section for someone selling an LS twisty battery pack.