Scanner opinions

[Hemlock_Mike]

:wtf: is that all about ? This was good info until now.

Am I missing something?

HMike

 

[Solonar]

Had a lot of problems initially. Also been working a lot of hrs, not much time to work on it.

In the middle of a slight redisign to replace the dichro's I got from an lcd projector with some better ones on newport mounts.

Scanners are still screwed up, but I had some other problems that were keeping me from doing a thorough tuning.

I had a bad setting in EzAudDAc.ini that was causing the lasers to only turn on at <25% power. Once I solved that, I found out that I needed a 12v psu for the FlexMod in order to power the GGW to full power.

My homemade dichro mounts used springs, and as the scanner or the room changed temp, the springs changed length causing beam misalignment.

The new psu should be in this weekend, then a couple of days to finish the redesign. Then I can spent a good day to get the scanners tuned hopefully.

 

[Solonar]

I finally was able to get back to this. I've changed to a 12v PSU for the flexmods. I changed to new dichro's and mounts(Soooo much easier to align the beams now).

Now I've got a new problem. So far the one piece of the scanner that has worked fine is the SoundcardDAC. Now when I connect it and fire up the scanner, I am getting a 2.3v signal on all 6 channels( even with no output from the computer i.e. all sound sources muted).

The effect is the I get no blanking on the lasers, and the galvo's are offset in one direction. The galvos scan just fine, but shifted off-center. The lasers modulate from the 2.3v to the 5v max signal.

I've double checked all the connections and solder joints and don't see anything wrong. I've tried connecting the DAC to different USB ports also.

 

[ElektroFreak]

To me it kind of sounds like one of the 6 channels is shorted to ground.. it's would almost have to be a blanking channel since your images wouldn't be good if one of the galvo channels is shorted.

 

[Solonar]

I seem to have the worst luck with cables. Turns out the USB extension cable was the problem.

Anyone know a good source of pass red/ reflect green and violet dichro's. My GGW is putting out 176 mw and only getting 14mw after the scanhead. I lose about 50 mw after the first dichro( pass violet / reflect green) and 80 mw after the 2nd dichro( pass red / reflect green and blue)

Another problem I'm having is getting a god RGB mix, as my green seems to be getting crosstalk from red and violet. If I turn all 3 lasers off in projector settings and try to turn just red or violet on, green comes on also?!?!?

 

[aXit]

Out of curiosity, are the transistors on the flexmods isolated from each other? It's fine to use one heatsink, but silicone pads and plastic bolts or inserts are necessary.

 

[ElektroFreak]

I seem to have the worst luck with cables. Turns out the USB extension cable was the problem.

Anyone know a good source of pass red/ reflect green and violet dichro's. My GGW is putting out 176 mw and only getting 14mw after the scanhead. I lose about 50 mw after the first dichro( pass violet / reflect green) and 80 mw after the 2nd dichro( pass red / reflect green and blue)

Another problem I'm having is getting a god RGB mix, as my green seems to be getting crosstalk from red and violet. If I turn all 3 lasers off in projector settings and try to turn just red or violet on, green comes on also?!?!?

That's usually caused by a setting in EZAudDAC.ini.. There is a list of channels and their assignments near the bottom of the code. For whatever reason (never really tried to figure it out) I could only get my RGB to work right with the following channel assignments:

[Channel Selection]
X=1
Y=2
R=5
G=6
B=3
I=4
AL=7
AR=8

You might then have to go into the RGB settings in Spaghetti and remap your colors.

As far as dichros go, I remember hearing something about Laser-wave having good 405nm dichros, but I've never bought them myself so I can't say for sure. Edmund Optics might also have something that will work.

 

[Solonar]

Out of curiosity, are the transistors on the flexmods isolated from each other? It's fine to use one heatsink, but silicone pads and plastic bolts or inserts are necessary.

yes, thermal pads and plastic washers attach the transistors. I triple checked before ever applying power.

OK, thx EF. I will try that and look into laser-wave.

 

[Solonar]

Your settings work better, I can isolate red and violet, but when turning green on red comes on also. Strange thing is, I can get all 3 colors to show during a show playback.

Ordered a dichro from laserwave.


Now I just need to sit down for a few hrs and tune the damn scanners, as I get nothing that even remotely resembles a graphic.

ILDA test pattern @ 20k

Laser Media Test pattern @ 20k

Quadrature squarewave pattern @20k

 

[ElektroFreak]

If you're working with a sound card DAC, you need to double-check your wiring. That kind of output is usually caused by one or some of the channels being shorted to ground.. In my experience it's always been a bad DB-25 cable, but I do know that it can also be caused by not having the soundcard set to 6 ch. or by using the wrong sound card drivers. Your scanners should be factory tuned..

 

[Solonar]

No indications of a short anywhere. grounds are connected to ground, and signal lines are isolated from ground.

Made a couple of changes, shifted the x and y cables to different lines. My breakout board has only 2 lines, and the signal cables have 3.

G x- x+ G y- y+ They were setup on x- x+ and y- y+.

I shifted the cables to G x- and G y-.


ILDA @ 20kps

ILDA @ 6kps

abstract type shows look ok, but anything that has a graphic or text looks horrible.

http://www.youtube.com/watch?v=dJK2GjCvRxk

 

[aXit]

Another common method is to tie x- and y- to ground, then attach negative DAC outputs to that ground.

 

[Solonar]

I tried that with jumper wires and saw no difference in output.

I want to determine if this is a scanner issue or a DAC issue. If its just that the scanners are crap, I will look in to getting a better set. If its a DAC issue, I have to look into a better one also(FB3?, though FB3 with 20k scanners would be a waste).

 

[Benm]

Try to connect either differential end of the signals to a scope in X-Y mode. This allows you to see what signal actually goes to your scanners, and eliminate any problems with your soundcard and compensation amps.

Grounding one of the differential signals seems like a bad idea. The whole idea about differential signals is that they are their own mirror image if you consider ground potential zero.

Using differential signals within a compact enclosure may seem pointless, and it often is, but it still is what your scannner drivers expect to see as input.

 

[aXit]

Problem is that drlava's correction amp is only single ended.

 

[Solonar]

That and the only scope I have is a single channel digital.