This is an ideal setup:
I have a 'friend' that wants to power one 9 mm Nichia at 2.6A with a flexmodP3.
Nice. Right?
Vsupply: 12VDC ATX PSU <= 15A
Mod Input: 3.3V GPIO on microcontroller (GND tied to ATX PSU GND)
My friend has setup many flexmods before, so he goes about his usual business, dials in a bias at 200mA, and a gain for 2.6A @ 3.3V on MOD. This essentially maxes out the gain ----> (2.6A/3.3V) ~= (4A/5V)
With the driver dialed in, he uses thermal epoxy to secure the thing to a large aluminum heatsink, and proceeds to solder up the LD after shorting the output momentarily.
Textbook. Right?
So after all this, no current. No red LED, no bias current, nothing.
My friend connects another P3 to the same PSU and LD, works like a charm. He then tries the original unit again, but nothing is happening.
He then reviews the board level for cold solder joints, shorts and retests conductivity through all his wires and joints.
LED lights up when he floats the interlock as it should, but closing the interlock doesn't enable current flow.
What is the problem?
My friend is feeling down about this, because it is delaying his group project laser engraver. Should he consider swapping boards? Attaching the working P3 board to the FET of the lifeless one?
I can't solve this one because I have yet to read of any problems without the LED turning on.
Anyone else experience this?