Usb Dac

[MechEng3]

I am guilty of using a MM. The Dac had some issues with one of the Dac chips not functioning and I sent to Marconi and he fixed it....replacing all tha DAC chips and a few other components. The reason I measured it this way is thatYadda stated that it was OK to do so if the laser was on and a non-modulated input were being sent to the laser. Before and now after repairs....still the max of 3.6 v or close to it.I am runnin analog lasers and on the bench my 473 unit was doing right at 312mW with 5 volts applied. Now I am lucky to get 175 out of it driving it with this DAC............Have you measured your laser output in lasecad? I would be interested in your findings.

[stanwax]

what are you mesuring the laser output with? If its lasercheck or similar then it wont give you an acurate reading as its not a steady state laser beam which is all they are designed to measure. Even drawing a circle the laser will be modulated - you can easily see where the circle begins and ends as it is turned on and off even during such a simple shape. If you look on a scope you will see a train of pulses the trace will be mostly at 5v but plunging to zero (or near) every frame. I will take a photo later of my scope screen and post it so you can see whats going on.

Rob

[Zoof]

If you are using Mamba, yes the frames are modulated to blank at the end or beginning of each frame even if the frame does not have blnaked lines.
I wrote a small testing program for easylase under windows that allows you to modulate each color manually with a slider. If interested I can post it at the end of this week.

[sbk]

You can choose to show blanking lines with the software, it will output a continuous full blanking voltage that you can measure with a voltmeter... And then adjust the output range by soft to see changes.

Is it really a problem that the card only outputs ~4.5 volts at full scale, when the laser blanking input is only working between 2 and 4.5 volts? (my 473nm Lasever works like that).

[MechEng3]

I am glad to see some understand the issue with it here. If your are in Lasecad, the laser can be displaying a single point...measuring very low output.But if you draw a square or circle and add smaller one inside themselves, you get higher power readings. Never the full power for modulation.I know the software reserves a bit for the sparkle fuction...it just places a specified amount of hot spots in the traced image. Even the TTL output jumper has the same issue. There has got to be a way to fix this without a big problem. I am just not electronicly{SP} savy enough.I thought an opamp with a seperate power supply to modulate the laser would work ,but it would have to be pretty fast to cover the analog end of things. Not sure what to do and where to start or just start over with a new DAC. Already have plans on getting new scanners and amp set.....just waiting for the word to send the $ for them.