So, I installed a two new simpledrive II that were left over from a project a few years back. I set the currents on my bench like normal. Next, I installed the drivers in the projector (after shorting the outputs). When I powered up the projector I saw a brief a bright blue flash. I thought it was strange as i hadn't seen a SD II do that before. Everything looked good after that. I ramped the current up and down with my potbox. I turned off the projector for a few min. When I turned it back on the same blue flash. this time it took three diodes to laser heaven and one is now low power. F@#k!!
I removed the driver and put it back on my bench. I hooked up a 1 ohm dummy load with my scope across it. The initial pulse was too fast to see on my scope. However, I did see a brief "flicker" of the trace. After about 5-10 power cylces the "flicker" of the trace seemed to go away.
Next, I pulled the projector over and hooked the diodes back up. No light "pulse" on power up this time. Tried a few more times, nothing. The remaining weak diode still worked when modulated. Crap. I'm now thinking my projector supply is doing something strange. I hook the projector supply up to the driver on the bench. Now I am back to the original set-up that killed the diodes except the driver is on the bench and not in the projector. No pulse at turn on and the power supply looks good on the scope.
Here is the set-up when the failure occurred:
12.5V on the supply feeding 2X simpledrive II. One feeding 2 1w greens on channel 1 and 1 1w green on channel 2. The second SD II had 2 M462 diodes in series on each channel.
I'm really scratching my head here. Anyone got any theories on what happened?
I did check to make sure none of the + or - leads on the diodes were shorted to the baseplate.
Obviously, I not gonna use the driver again. I'm grateful that it wasn't the 1w greens that got toasted. But a little nervous about not knowing what happened.