Baffled beyond belief. UPDATE: Found solution!

[yathern2]

So a while ago I built my first laser, one of moh's C6 Just-Add-Diode kits, with an A140 445. You know the deal.

Well about a month ago I decided it was time to resolder my connections, because the laser wasn't always turning on, it would go on and off with shaking. I resoldered the whole thing, and put it back together, and viola! It doesn't work at all. I tried it again later, and it worked, and then stopped. I hadn't been able to get it working again for the past month, and didn't want to keep messing around with it without the proper tools.

Just a few days ago I got my first multimeter and DC power supply. After getting used to it by testing them on some old electronics projects I had lying around, I wanted to see if my diode still worked by direct driving it.

I turned the voltage all the way up, current all the way down, hooked it up to my diode, and it worked! (I only ran it up to .5A, just to be safe) I was very glad I got it to work. I then tested the driver, and the host, and batteries. Essentially every individual part of the laser, and each one seemed to be working correctly.

Then, I tried driving the laser through the driver, but powering the driver through my DC supply. To my suprize, the polarity was opposite of what I expected. I had to put the negative lead to the positive, and vice versa in order to get it the laser to shine.

This begs the question: WHAT ON EARTH IS GOING ON?

Now, I'm still quite the amateur when it comes to electronics and lasers, though I always like to play things safe. But this is utterly baffeling to me. Even if I soldered the incorrect wires together from driver-to-diode, I feel like it still shouldn't work if I give the input of the driver the wrong positive/negative. In my thinking of electronics, there must be some reason why two wrongs don't make a right. But it seems like they do.

Before I resolder and connect green-to-black, red-to-white, am I correct in thinking this will solve the problem? I'm leaving my home in 2 days, and I want to get my laser working again by then. I'll put up a picture in an hour to show what I mean. But currently out of the moh's driver comes 2 wires, white and green. I assumed white was negative, and green was positive. Thusly, I connected white to black, green to red. But will the opposite fix things?

EDIT: I figured out the problem below, but not the solution... It was partially like ARG said- the tailcap.

EDIT 2: I resoldered the spring in the tailcap, and just played around with it and now it works!

 

[ARG]

Re: Baffled beyond belief.

Sounds like the tail cap to me! I had the same problem, took me some time to figure it out.

Try using your DMM in ohms on the tailcap, test it to see if it works. If it's dead buy a C6 host and take the tailcap off that.

 

[yathern2]

Re: Baffled beyond belief.

Sounds like the tail cap to me! I had the same problem, took me some time to figure it out.

Try using your DMM in ohms on the tailcap, test it to see if it works. If it's dead buy a C6 host and take the tailcap off that.

That's what I thought at first too, but then I tested it like this, and it seems to work fine.

The only difference is when it is connected to the driver, the spring would be compressed, possibly causing it to lose connection somehow.

My real question though is why the positive/negative polarity is reversed! I'm very confused about this. Green should go to red, white to black, correct?

EDIT: Okay I finally figured it out!

So after lots of testing, I finally decided to resolder the wires in the opposite way. red-to-white instead of red-to-green. I normally would know which goes where, but since moh's site is down now, there was no way to find out. I reversed it, but it still didn't work. Remembering what ARGLaser said about the tailcap, I decided to circumvent it by just removing the tail cap and connecting the host and the negative side of the batteries with a wire and it worked!

Now I have to either find a new C6 tailcap, or try to fix it myself. It looks like the spring is soldered on, do maybe I'll desolder it and take a better look inside. I'm leaving home in less than 48 hours, so I want to find a solution soon.

EDIT 2: Okay I messed around with the tailcap a bunch and now it works. If it stops working while I'm away, I think I can fix it without needing any extra tools. I just have to twist around the cap or something.