My scanners displaying test pattern

[mliptack]

I'm not sure how similar the DT-40's are to the DT-40 Pro's but in this thread:

http://www.photonlexicon.com/forums/...ead.php?t=2266

about 3/4 the way down there is a post from yaddatrance he attached a PDF file which shows what to adjust and what it affects. It seems very helpful (I personally own DT-40 Pro's and have yet to actually tune them using his methods, but it seems like it might be of a lot of help).

-Max

[andy_con]

Hi Andy,
That problem probably be from "overdriver".
So the scanner is dead.You can't tune it to work perfection.
Now you may :
1.That scanner use for beam show only,no any prblem,you almost can't find where different.just show for animation very bad.
2.Send to me repair.
3.upgrade to DT40pro.
Jian

dead you must be joking!!!! ive hardly used them

they display animations just fine you cant notice any problems.

how do for tem to be repaired if they are faulty???


im not turning any pots until i know whats what.

jian do you have any data on what pot does what??

[andy_con]

took me a while to find but bingo

http://www.photonlexicon.com/forums/...highlight=dt40

what do i need to turn to start tuning?

[andy_con]

ok at a distance of 3 metres, the width is 1m and height is 1.35m

so 15% = 8 degrees

[buffo]

OK, I finally got home where I could look at the picture you posted. Your "Y" scanner amp needs to be tweaked for sure. While I can't really walk you through a complete tuning right now, I might be able to help you get it good enough that you can live with it until I finish the scanner tuning tutorial sometime after Thanksgiving. Try this first:

With the size set to 15%, load the test pattern. Now, in the center square, notice the overshoots on the upper left and bottom right corners? (The line extends beyond the corner, up on the left and down on the right.) Start by adjusting the low frequency damping. Try turning it about 1/4 to 1/2 a turn clockwise and watch those overshoots. They should get shorter. (If they start to get longer, STOP, and turn it counter-clockwise instead.)

Try to get those overshoots adjusted back so all you see is a dot at the corner. For now only use the low frequency damping adjustment. You may need more than a half a turn - just go slow and watch the overshoot lines. So long as they are getting shorter you are OK. (If they get too long, the scanner can get out of control and go ape-shit on you. That's bad.) You want the overshoot to stop right at the dot that is the corner. (Don't be too concerned if you start to see another line growing on the other side of the corner - we'll fix that next...)

Once you've dialed in enough low frequency damping to get rid of those overshoots, look very carefully and see if the line segment got "thicker" beneath the corner at the upper left, or above the lower right corner. By "thicker", I mean it will look like the beam is re-tracing itself for a short distance. (Or if you see a second line segment roughly parallel to the one connecting the corners.) If you see this undershoot, you'll need to add a small amount of high frequency damping to get rid of it. BE CAREFUL! Small adjustments only. It may only take 1/4 of a turn or less. Again, try clockwise first, and if the undershoot gets worse, go the other way. (The early DT-40 amps had backwards pots on them, so turning them clockwise would mean LESS damping, which is backward...)

When you're done, you want to see a nice clean dot at the corner with no overshoot or undershoot.

Once you've done this, take another picture of the test pattern and post it here.

Adam

[andy_con]

ok thanks,

am i being stupid which one do i tweat to make the frame wider?

[andy_con]

ok i tried adjusting the position scale and position balance but that didnt make x wider???

i tried the low freq damping and that didnt seem to do anything either

some pics

[andy_con]

shame my green laser is crap

[andy_con]

[p1t8ull]

Andy, the pot marked input gain will increase the scan size.

Go easy tweaking pots, until you totally get what Adam said in his quick guide to tuning above - you'll let the smoke out of something