Stanwax ILDA Interface Board question

[ZeroPoint]

Thank you, I have split the ground two ways to accommodate signal ground and power ground. the good news: the board is working, the leds go through their paces, the scanners work properly and the ILDA signal is flowing well. the bad news: the laser is not modulating. i noticed as soon as i turned the projector on that the laser began lasing even while the timer leds were flashing. i double checked to make sure nothing was shorted and all the wires are properly connected. everything seems to be in order. how can the laser emit a beam when there should be no signal going to the modulation line? im starting the think there may be something wrong with the driver itself. i noticed a few unusual behaviors. 1) i initially had the laser set to 450mA (by the way i am using a 1 watt 445, i believe its the a-140 diode) and when i turned the projector on the diode would flash twice and go off causing the interlock led on the driver to light. i solved this issue by turning the current WAY down to almost nothing. now it is emitting again. 2) only the 0 bias pot on the driver seems to have any affect on the current to the diode. the gain pot was not increasing current when i turned it up. since the 0 bias pot is only for standby current and the gain pot is for max current this seems wrong. is anyone familiar enough with these drivers to know what might be causing these issues and could this be the reason i can't modulate the laser?


(edit - this reminds me of another question i had. i currently have the diode connected to the pins for the dark blue module on the board, since this will be the only blue in the projector should i leave them where they are or would it be best to put them on the pins for regular blue?)

[polishedball]

Did you apply 5v to the modulation input before setting gain? You will have zero effect moving gain if u didn't. Have you read drlava setup procedure? I tie the ps grounds and mod ground together. For single return point

[stanwax]

The dark blue connection is for an additional laser - if you only have one blue then it should be connected to the blue line. Appart from anything else the dark blue out will only work if your hardware/software (dac) supports more than 3 colour lines. As John said above you need to set the the gain of the FM before you you hook it up to the ilda board. Turn the gain pot right down (anti clockwise) and apply 5V between the mod input and ground. Hook up a voltmeter set to mV scale across the big black resistor on the FM. Turn the gain pot up while monitoring the voltage across the resistor. This is 0.2 ohms so you can work out the diode current by ohms law. voltage reading(in volts)/resitor value = current in amps
So if you measure 0.3v or 300mV the current will be 0.3/0.2 = 1.5A If you want to work out what value to aim for, you can work that out by Desired current (in amps) x resitor value.
Therefore if you need to set the current to 300mA you get 0.3(amps) x 0.2(ohms) = 0.06V or 60mV
Once you have this set you can hook up the mod to the ilda board colour line connections. Then when the FM gets a signal from your controller you should see output.
Rob

[ZeroPoint]

thanks again. i ended up figuring it all out the next morning. turns out all i needed was some sleep. though the driver had been set up properly in a previous setup i somehow managed to turn the 0bias way up and the gain way down at some point before putting it in this projector. once i realized this i reset it and everything works fine now. thanks again for everyone's help! once i get the green in ill make a vid and post beams