Ryan v. The Headlamp

I started my new part-time job yesterday doing Patents for Texas Tech - should be pretty fun. But because of that and some other things going on, I didn't get home until 10 PM. I still had some studying to do, but rather than do that, I opted to replace the batteries on an old headlamp. Little did I know what I was beginning...

Of course there's a backstory - I own multiple flashlights, headlamps, etc. This particular headlamp I've owned for about 9 years, and I distinctly remember buying it before my first foray to Nutty Putty Caves. It's not an LED, but rather a heavier but more powerful "straight" beam, that really focuses the light and lets you see a good 20-30 feet.

Well, the batteries I had in there had corroded a bit (they were a couple years old), leaving a nice layer of alkaline material all over the electrical contacts. So I got some q-tips & rubbing alcohol and cleaned it up, replaced the batteries - no light. Cleaned some more - no light. Now the fun begins. I'm not one to back down from something like this...

So I busted out my multimeter - checked the voltage on the batteries - both at ~ 1.6V, right where they should be for out of the box AA batteries. Put them in the light, check the contact points, reading just below 3V, right where it should be for 2 batteries in series, accounting for added resistance of the light. Good so far.

I look at the bulb - filament looks good. Change the multimeter to measure resistance - picked up a small resistance, meaning the light circuit wasn't broken. It should still be working. I swap bulbs anyway - nothing. Measure voltage inside the 'cap' the light sits in - voltage good.

At this point I'm becoming frustrated - either both of my bulbs are busted and I don't know how to use a multimeter anymore, or something isn't making contact. So I took the next step,

and hit it. Repeatedly. and it worked.

Swapped bulbs, made sure both bulbs are still good (they are), cleaned up my tools and was done. 11:30 PM, over an hour on it, but it works.