buffo
Yeah, that's a very important step. If you don't know what the pots do, DON'T TOUCH ANYTHING. You can make it really bad - to the point that you need an oscilloscope and a lot of time to get them back to where they are supposed to be - if you start tweaking the wrong pot.Originally Posted by gottaluvlasers
Well, it's not sensitive like brain surgery or anything. You do have some leeway on the pots (plus or minus a half-turn or so before things start to really change for the worse), and the scanners will give you hints when you're doing something wrong. (Auditory warnings, like screeching, and visible warnings, like oscillation in the pattern.)never done scanner tuning before. i am assuming, that this is a VERY sensitive procedure?
Unfortunately you *CAN* break a set of scanners by tuning them; if you let them get away from you that is. There is no inherent safety on the scanners, so if you just crank away and don't pay attention, yeah, you can ruin them. But if you go slow and watch how the pattern changes, you will be fine. It's not "easy" to break them, but it can be done.are the amps and/or scanners forgiving if the adjusting goes above OR beyond some certain *threshold* limit of adjusting? in other words, is there a way that i can actually overdrive the scanner and break it?
Tuning is a somewhat tedious process. You add a little gain, then you add just enough low frequency damping to get rid of the overshoot. Then a little more gain, then more LF damping. Eventually, when you get the gain up pretty high, you'll start to get undershoot, which means you'll need to add high frequency damping. Then it gets tricky, because a change in any one pot when you're up that high will have an effect on what the other two do to the pattern.
They'll probably supply you with tuning instructions too. Or you can just look on the web; I'm sure there are several documents out there that explain the layout of the amps, and you've already got some links (above) to get you started tuning. Yeah, Cambridge is good about that...i am going to have to try to find a layout or schematic or something of my amp drivers. i remember Cambridge, the few times i spoke with them, being VERY customer friendly. will they supply this info to me you think? (schematic or layout for the proper adjustment pots?)
I'll try to work on my tutorial some more this weekend. Mainly I want to incorporate the *great* tips that Bill Benner shared with us at FLEM 1.5 back in October of last year. (Things like turning off the blanking so you can use the re-trace lines to see how your scanners are doing....) Unfortunately, all the video is crap, so I'm really stuck as to how to illustrate things.
If you test pattern looks like crap, eventually you'll find ILDA frames that look like crap as well. Getting the test pattern dialed in means that your scanners will be as good as they're going to get. Sure, you can display beams even if your galvos are horribly out of tune. (How accurate do you need to be to make a line?) You can even display most graphics with poorly tuned scanners... But eventually you're going to notice that certain images just don't look right. And the more you watch your graphics and pay attention to things like tails, oval circles, and wavy lines that are supposed to be straight, the more distortion you'll notice. Tuning will solve these problems.I understand my ILDA test pattern looks like crap, BUT- if everything else projected looks good, is this neccessary to perform? (the tuning).
There are parts of the ILDA test pattern that are analogous to a stress test. (Not a test to failure, but a test to max spec.) However, there are also parts of many popular ILDA images that push the galvos to the same extent. If you get the scanners dialed in correctly, they will perform at their maximum *without* any danger of overheating or resonance damage. Screw up the tuning, and that protection is no longer there. (Not to mention the fact that your image quality will suffer.)the ILDA pattern is probably almost like a *stress test* for the scanners correct? in other words, a test to really push them. do they perform like that under normal ooperating circumstances?
Adam
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