Degrading scanners.... WTF ?

[James Lehman]

Haiku's are easy
But sometimes they don't make sense
Refrigerator

This is totally my kind of humor!
That's awesome!

Q: How many surrealists does it take to screw in a light bulb?
A: Fish.

And remember....
Never anthropomorphize computers. They don't like it.

James.

[allthatwhichis]

Mine looked like that right before the Y scanner crapped out. I just sent you a PM with a possible test solution. Let me know if I can help.

I wonder if our esteemed Janitor got home OK after his little walk...

[LesioQ]

A long shot. External light leak into scanner position detector compartment ?
Try to 'apply darkness' to scanner back ends. Or otherwise - shine a handheld laser to their housing, near the connector while scanning ILDA pattern and watch for major changes.
Second shot - power supplies stability fed to position detector emitters ?
Piotr.K

[buffo]

Hey Randy;

Wow - that test pattern looks a lot worse than it did 2 weeks ago!

Not exactly sure how it happened, but I agree with Barry: It looks like you've got too much LF damping on your Y axis. You might try backing that off a good bit first and see if the circle comes back to normal. (Excessive LF damping will give you undershoot, just like too little HF damping will.)

Give me a call later tonight when you've got time to fiddle with them and I'll talk you through it. If nothing is physically wrong with the galvos, then we should be able to get them back in tune. Still not sure why they changed so drastically though.

Adam

[Stuka]

Thanks for all the suggestions, folks!

I'll tinker with the tuning later this evening and see what happen next.

More to follow.......

Randy

[Stuka]

SUCCESS!
(For now, at least!!)

Turns out I only needed to make very MINOR adjustments to HF and LF damping on the Y-axis, along with a little servo gain tweak. Things are now looking pretty good with the ILDA, quad wave, and color wheel patterns! (see below)

Thanks again for everyone that helped steer me in the right direction!

However -
I have noticed that there is still some very minor drift in the tuning as the scanners continue to dispaly the various test patterns. As we speak, the bottom "rung of the ladder" on the ILDA test frame is beginning to curl up slightly, and I'm already starting to see overlapping lines and "tails" beginning to appear in the various color wheel patterns.

So, while the problem appears to be "fixable" for now, it does appear I'll be dealing with this on a recurring basis. Any suggestions on a "permanent" fix?
(Other than investing in a set of Cambridge scanners? )

Thanks!

Randy

[Hemlock Mike]

This is for sure an interesting read as I have a new Scanpro20 I'm building up

Mike

[Pitts]

Hey Admin...

Bloody brilliant....

Ray

[buffo]

Could be that they just got knocked around in the hustle and bustle surrounding SELEM... After all, 4 hours in the back of your truck might have loosened the pots a tad. If it was only a small adjustment, I wouldn't be too worried about it.

Adam

[James Lehman]

I might be a bit ticked if the adjustments fixed it but then it started to sag again, right before my very eyes!

James.