Question about scan size

[ElektroFreak]

I believe I may already know why this is happening, but I'd like some expert opinions in case I'm way off:

I have a 30kpps RGB scanner (LKI LK-MC2). I'm not sure about the manufacturer of the galvos, but they run well with very clean output, so they seem to be high-quality (the whole projector is extremely good for a Chinese system). When I run the projector in DMX mode using the built-in program board, I get a very wide scan angle, but if I hook the system up to my soundcard DAC the angle is only half as much..

I have two other green systems (both scanpro 20s) which provide full angle scanning regardless of the source, so I'm a little confused as to why the RGB performs differently. I suspect it has something to do with the fact that a soundcard DAC is single ended rather than differential, but that doesn't explain why I still get full-angle from my other system using the same DAC..

Anyone have any ideas?

[mccarrot]

DA DB-25 pin 1 contains the X+ signal, and pin 14 contains the X- signal. Often times, when pin 1 is going from 0V to +5V, pin 14 will be going from 0V to –5V. The actual signal level is found by subtracting; thus +5V minus –5V = +10V. This means that the voltage level that the X scanner amp should sense is +10V.


So the big question is, is you soundcard dac putting out +10V at full angle?

[ElektroFreak]

By my measurements it is putting out almost exactly that, yes.

That was my first thought as well, but the fact that I get full angle on my other two projectors when using the soundcard DAC makes me think that the issues may be something else..

[mccarrot]

are you sure you use the input + and input - of the galvo's and not input + and GND?

[ElektroFreak]

Actually, no. I'm not entirely sure how they have everything wired up in there since I didn't build the system. I'll have to look into that, since they may well have things wired a bit weird. I bought the projector to tear down and rebuild since the hardware in it is very good quality.. it was by far the cheapest source of RGB CNI analog lasers, galvos, DMX board, etc. The dichros are non-adjustable, so some good mounts are in order, but that's the worst part of the system. It also lacks safety features, but everything else is very nice.. The circuitry involved in the ILDA input and the switch for changing between DMX and ILDA is worth a look, though. Perhaps it would be best to just bypass this circuitry completely and connect the ILDA X,Y pins directly to the galvo amps..

[mccarrot]

Rebuild

[slicklasers]

Perhaps it would be best to just bypass this circuitry completely and connect the ILDA X,Y pins directly to the galvo amps..

YES.... Just wire straight to the scanner amps, and the analog signal on the power supply... bypass the crappy dac completely...

[mccarrot]

I have a 30kpps RGB scanner (LKI LK-MC2).

My housing is also a LK-MC2 housing, but nothing is original in my case

[ElektroFreak]

well look at that! so it is.. you're the only other person I've seen with one. IMO for a Chinese system they're an extremely good value as a source of decent RGB lasers and galvos, etc. for rebuilding later with better parts..

Mine actually came with some pretty hot CNI analog modules.. I'm quite happy with those. My blue is rated at 50mW, does 100+. The red produces rated power, but loses a BUNCH in the optics, so that sucks, but the green is rated at 100mW and does a solid 150.

The most disappointing thing about the system to me is the optics..

[mccarrot]

I would reccomend these as dichro mounts, much more stable than the fine adjustable lab style dichro mounts laser wave sells