445 diode on FM2, won't increase in power

[norty303]

I've got 2 identical 445nm modules built from the very first batches of A140 that Dan did on the group buy.

I'm running them both on FlexMod2's and powering with just under 6V so they should be ok for a watt.

One of them will go up in power fine when i turn the gain up. The other one hits about 620mW and then won't go up any more. I can turn the gain pot lots of turns past that point and nothing changes on the power output.

I would ghave thought if it was the diode reaching a plateau, turning the gain would eventually pop it, but it doesn't seem like that to me (I've wound the gain up LOTS!). Perhaps the Flexmod is the culprit?

[-bart-]

What is the voltage over the diode ?

[logsquared]

I would suspect that particular diode has a high Vf. In the past, when I have had similar problems using the flexmod, going .5V higher on the power supply fixed the problem. (make sure to turn down the gain first!)

[norty303]

Hmm, the Psu is now at its highest voltage it can give. I expect switching out the diode may be the most cost effective/least hassle solution.

[DTR]

Does the current draw from the driver increase when you turn the pot?

[norty303]

I haven't been able to check that far. I was just adding a bit more power whilst cleaning optics. It's got a lot of work the next 2 weeks so didn't want break something I don't have time to fix. I'll check the current once this run of work is over.

[m0f]

Might be worth double checking the solder pads for low / high (I'm pretty sure it was the fm2 that had those). Make sure to wind the pot right down first just in case.

[kecked]

I had that and the diode eventually went led

[norty303]

I think m0f has it actually. I think i set them to low (1A) as I thought it was probably enough at the time. I suspect this is just a poor performing diode and needs a bit more grunt.