Improving scan patterns

[mrblack927]

Hi all,
I just (mostly) finished by homebrew rgb projector, and it looks awesome. One thing I noticed however is that my my test pattern kinda, well, sucks. The projections are alright, not great. I'm wondering whether its an issue with my dac, scanners, or just the tuning.

Keep in mind that I'm using pretty low-end equipment, so I'm not expecting much, but I plan on upgrading incrementally over time.

Right now I'm using scanpro-20's and norm's dac. Here's the catch though... when I got my scanpro-20's, the serial numbers on the scan heads didn't match the serial numbers on the drivers. I didn't think it was a big deal at the time so I kept them rather than shipping them back to Australia for a new set. Of course, now I know that my "factory tuning" was nullified by the mismatched equipment so I tried to tune them myself. I followed the guide to the letter but I cannot get a perfect pattern no matter how I try it. Now I'm starting to wonder if I can't tune it correctly because I'm using norm's dac to drive it (ie. what if they are perfectly tuned but the pattern is sloppy because the dac can't keep up).

So yeah, anyone have any thoughts? Do you think I should just keep on attempting the tuning process or invest in some new hardware, scanners or controller?

[cfavreau]

Post pictures of your test patterns. We can help more with some pictures.

Also which of Norm's DAC's are you using , LPT DAC? or USB DAC?

[mrblack927]

Test patterns attached, believe it or not this is the best I've gotten it tuning by myself. I'm using a norms USB dac...

[gottaluvlasers]

DEFFFINITELY a tuning issue.

1) are you sure you have your pots correct? meaning, are you adjusting the proper pot for Offset and such. not adjusting "gain" when youthink you are adjusting position. you have a good diagram of the layout of your pots?

2) scanners should definitely be matched with the amps. however, with a re-tune you should be able to get them pretty good.

the scan pro 20s arent going to project perfectly. they are a beginer scanning system. but i think you should definitely have a better pattern than that.

i hope you have the right amps for your scanners.

-Marc

[cfavreau]

Point output rate is definitely faster than the scanners are tuned for. Which DAC are you using? How fast is your point output rate?

Also it is just good to practice tuning. The scanners with the low and high frequency damping are harder to tune than the old ones with out it. I find that most of the time I actually over tune things where there is too much damping and backing things down often improves the tuning. Also did you you start from the ground up or from where they were factory set?

One more thing... scan angle has a big effect too. It doesn't look too big but how far are your scanners away from the wall?

[mrblack927]

Yeah it looks like I had the pps set to "auto" and it was running way too high. I set it to 20k and the patterns look better. Hell, I'm just happy to see full color right now. I just finished this projector over the weekend. I've got to dig up my good camera and take some pics.

Thanks for your help guys. I still dont know if I should get a better dac or better scanners next. I mean, these scanners suck but this dac kinda sucks too. Its only got TTL color outputs!

expensive hobby

[cfavreau]

So you are using Norm's USB DAC, the FSX 1.X. You may want to try tuning to 12kpps first and see if you can do that. Then work your way up to 20kpps. I don't think there is a 20kpps exactly... I think it is 24kpps. Try the 12kpps then 16kpps.

I think if you get your stuff figured out and running right... your equipment will not be sucky.

Also what does your Quadrature pattern look like?

[mrblack927]

You're probably right. I can get a little impatient at times. I'll try tuning them again tonight and post up my results.

And yes I'm using FSX (1.1.5 I think?) with software either NLS or Spaghetti. By the way do you know any other good free software to use with FSX? Did you ever get around to writing an easylase wrapper?

[ElektroFreak]

Are you using blanking optimizations in your software, or have you adjusted the blanking timing in the software? To me that looks like your blanking timing is off..

Spaghetti has "blanking optimization" controls in the scanner settings.. adjusting these settings might help you greatly.

[cfavreau]

Blank timing / optimizations are not in there. In fact I would turn off blanking for doing the tuning. Not sure how in NLS though... There is some good information in the blanked sections that helps with tuning.