FlexMod P3 Analog/TTL Laser Diode Driver

[polishedball]

I'd like to know that too. Maybe it really is missing a part?

That be hard to miss one would think and I thought Andrew had to tune these before shipping usually. I'd contact the supplier.

[varesa]

That be hard to miss one would think and I thought Andrew had to tune these before shipping usually. I'd contact the supplier.

I have contacted them a while ago, but I'm still waiting for a response

[michelrietveld]

i think i have an older version, see manual link:
http://innolasers.com/laser/FlexModP...dP3_Manual.pdf

Michel

[michelrietveld]

funny that the picture on the website :
https://illuminationsupply.com/laser...l#.Uuy1LyOA10s
does show the large black resistor whilst your picture does not
i would say "doa" since it is missing a crusial component.

Michel

[varesa]

Should the resistor be 0.2 Ohms? I tried connecting a big .2 Ohms power resistor there, but it made the driver push against the current limit on my supply and heat up the FET fast (even with the heatsink), even if I had no load connected or the interlock-loop was open. There is clearly something wrong with it...

[polishedball]

Should the resistor be 0.2 Ohms? I tried connecting a big .2 Ohms power resistor there, but it made the driver push against the current limit on my supply and heat up the FET fast (even with the heatsink), even if I had no load connected or the interlock-loop was open. There is clearly something wrong with it...

If I recall correct. The FET sinks all the supply voltage when there is no load.
What is your supply voltage it gets hotter the higher the voltage.

[michelrietveld]

did you follow the steps as described in the manual for which i posted the link?

[varesa]

So I soldered back the .2 Ohm resistor I found, but it seems to have the same problem I had last time: it outputs the full current.

I have tried following the instructions ("Setup and operation" part), but it does not react to the trimpots. When the interlock loop is broken it outputs around 0.5A and with the interlock loop closed it outputs whatever my PSU gives it (around 2A currently). It also has the effect of dropping the input voltage to about 4 volts as the PSU hits the current limit (again around 2A).

[michelrietveld]

did you make sure to turn back the multipot several times until you hear a clicking so you know that you turned it all the way down? maybe 25 times counterclockwise or so.
to turn down the max current to the diode.

[varesa]

did you make sure to turn back the multipot several times until you hear a clicking so you know that you turned it all the way down? maybe 25 times counterclockwise or so.
to turn down the max current to the diode.

Yes, I have turned it until it clicked. The 0-bias / gain pots have no effect on the current. Also one thing that proves (AFAIK) that it is propably not an issue with the pots is that it keeps supplying (even though slightly lower)
current even if the interlock-wire is disconnected so that it should disable the output completely.

Any ideas what might be the root of this problem?