I would not trust only using a multimeter to test the diode, I've tested many diodes to not register on the diode test function on the DMM but work great when hooking them up to a laser driver.
It never hurts to try out the diode, especially if you think its already dead, can't kill something if its already dead.
-Kendall
I would not trust only using a multimeter to test the diode, I've tested many diodes to not register on the diode test function on the DMM but work great when hooking them up to a laser driver.
It never hurts to try out the diode, especially if you think its already dead, can't kill something if its already dead.
-Kendall
It depends a bit on the multimeter. Many will in fact send enough voltage to make the diode work like a diode - often its just the meters battery voltage with a large series resistor. The meters usually display the voltage drop in milivolts though, and many have a range limited to 1999 - which may not be sufficient for laser diodes or leds.
You can test your meter for this behaviour by measuring 2 ordinary diodes in series. It should display double the value of 1 diode. If you hook up 3, its likely to be just at or just beyond the 1999 mV maximum reading.
More expensive meters will likely employ a current source limited to a lower voltage for the diode test.
The fluke might work because it either goes to 3.999 volts which is plenty, or auto-ranges so that 2.00 or more can be displayed.
I would be careful using lab supplies set at some voltage but with current limiting enabled.. some of them have output caps after the current regulating mechanism, and can give your diode a deadly jolt even when configured to safe current levels... similar to output caps on drivers and dodgy diode connections.