DT40 scanner problems

[andy_con]

ok ive noticed this for a while, anyone got any ideas??

see the zig zag on the x galvo

help please

the tail

[carmangary]

It's on the y, not the X. I had that problem on mine when I got them and it turned out that they were overtuned. But, I know you tuned yours so that is probably not the problem. So, maybe it is noise or you have a problem with your driver. Did you try swapping x and y cables to see if the oscillations follows the driver board?

[mliptack]

Gary's got some good advice! If you swap the cables you'll be able to see if the problem persists in the same galvo. If it doesn't it is likely noise from your power source. Pay close attention to the signal cables from the ILDA connector all the way to the drivers. Generally if you do need to run any power around those signal wires run them at a 90 degree angle not parallel to them!

-Max

[buffo]

That still looks like a tuning problem to me, Andy...

Adam

[jian725]

Hi Andy,
First what size mirrors currently?5X10 or 7X12?
Do you tune the driver?If not try adjust the Y notch filter.
Another problem is the speed too low.When the speed set to 18-22kpps,maybe creating resonance,Set to 25-30kpps the problem lost.
See attach.

[andy_con]

It's on the y, not the X. I had that problem on mine when I got them and it turned out that they were overtuned. But, I know you tuned yours so that is probably not the problem. So, maybe it is noise or you have a problem with your driver. Did you try swapping x and y cables to see if the oscillations follows the driver board?

thanks gary will give this ago tonight.

i did tune them i may try adjusting the y again see if it helps or not.

Gary's got some good advice! If you swap the cables you'll be able to see if the problem persists in the same galvo. If it doesn't it is likely noise from your power source. Pay close attention to the signal cables from the ILDA connector all the way to the drivers. Generally if you do need to run any power around those signal wires run them at a 90 degree angle not parallel to them!

-Max

ive taken great care about running the wires to the galvo's so im pretty sure its not noise. plus both X and Y are in the same location and its only happening on one galvo

That still looks like a tuning problem to me, Andy...

ill have a play tonight. what should i be turning pot wise fo loose this??

Hi Andy,
First what size mirrors currently?5X10 or 7X12?
Do you tune the driver?If not try adjust the Y notch filter.
Another problem is the speed too low.When the speed set to 18-22kpps,maybe creating resonance,Set to 25-30kpps the problem lost.
See attach.

i dont know the size jian but i brought them from you, so im guessing they are correct?

they were running at low speed, ill do some testing tonight


thanks for all you advice guys

[buffo]

Andy;

You can try playing with the notch fiilter like Jian said, but I suspect that isn't the problem. I've actually got the notch filter removed on my amps. (You have to short the connector if you do this.) As fas as I've been able to tell, the notch filter doesn't have any significant effect on scanner performance. (Bill Benner at Pangolin was the one that originally suggested removing the notch filter.)

Load up the quadrature square wave pattern and see what your overshoots look like. Also, pay particular attention to the corners; see if you've got any undershoot. Tweak the HF damping down *very* slightly and see if the dots become more distinct. Then flip back to the test pattern and look for your wavy lines again.

I'd also suggest you turn off blanking and check that re-trace line I mentioned in my scanner tutorial writeup. I suspect you'll discover that the line is missing the bottom edge of the pattern (adjust LF damping to fix) and it's probably got some waves in it as well (adjust HF damping to fix). Remember that you can rotate the image 90 degrees in software to allow you to check the other axis...

Adam

[mliptack]

Was it Bill? I originally heard about the notch filter removal from Yaddatrance. But yeah, definitely an easy thing to do.

[andy_con]

errr right alot of that went straight over my head but yeah ill see what i can do right now

[andy_con]

ok x and y swapped. to make it big enough i had to make the image bigger and turn the scan rate down.

normally image size is 13% which is 8 degrees and 100% for speed is 30k

i ran this at 20% image size and 70% speed

ill try get some better pics

the image is squashed and i think there is still some distortion in Y