Thanks @Firefox3d! I’ll order some of those Nichia diodes.
In the meantime, I tried to answer my own question about pinouts. I wasn’t quite ready to rip apart my laser yet, but inspecting @geggen20’s photos from a Form 1+ module and @Dudemeister’s photos from a Form 1 module, I think the Form 1+ laser module circuit might look something like this:
I’m guessing Q1 is some kind of constant current LED driver? (I couldn’t make out the markings on the chip).
I took some measurements on my Form 1+:
| Pos Probe | Neg Probe | Voltage (idle, lid closed) | Voltage (spot test) |
|---|---|---|---|
| Red | Black | 2.64V | 4.26V |
| Red | Yellow | 11.12V | 11.09V |
| Black | Yellow | 8.47V | 6.81V |
| Blue | Yellow | 4.91V | 3.44V |
When the lid is open they all drop to near 0V.
In short, the voltage between the red and black leads controls the laser power, and the blue lead senses current from the photodiode.
Armed with all this, I was comfortable hooking my original laser up to a bench supply (positive to red, negative black) and ammeter (positive probe to blue, negative probe to black), to get some baseline characteristics:
| Red | Current Draw | Blue (Sensed) | Notes |
|---|---|---|---|
| 0V | 0mA | 0uA | |
| 0V | 0mA | 0.4uA | Shining a flashlight into lens |
| 3.1V | ~0mA | 0.1uA | Laser spot appears (very dim) |
| 3.2V | 10mA | 0.1uA | |
| 3.6V | 20mA | 0.3uA | |
| 3.8V | 30mA | 0.4uA | |
| 4V | 40mA | 1.3uA | |
| 4.1V | 50mA | 14.4uA | |
| 4.2V | 50mA | 26.2uA | Similar brightness to spot test |
| 4.4V | 60mA | 46.3uA |
(Module Current Draw is to nearest 10mA)
Unfortunately I didn’t get to characterize the replacement module. It just started sucking up current with no emission, leading me to believe the laser diode is shorted. When I peer into the lens I don’t notice a beamsplitter like I see in the original, although I do get a sense current on its blue lead when I shine a flashlight in.
A random bit of trivia I noticed while investigating: R1 in the voltage divider on the original Form 1 is a 1% tolerance resistor, but for the Form 1+ became a 5% tolerance one.