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Thread: Wanted, Galvos or amps

  1. #1
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    Default Wanted, Galvos or amps

    Hey everyone, I have a pair of G-120s and the amps I have are not very good at all. Maybe 8K after about 2 hours of tuning. I am looking for some decent amps (if anyone has any available). Maybe MiniSax or any of Selwin's old amps. Either that or, if anyone is looking to get rid of some scanpro15's or 20's, heck even 30's if the price is right, I would be interested. Then I could just use the 120's for beams or abstracts. Please PM me if you have got obsolete galvo stuff to clear or amps that'll work with G-120s. Thanks!!
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    Woa dude, how bout taking a pix of what you got, so we can see whats up. You sound worse then Kryten In the dispair squid episode of "RED DWARF". I need a picture of your mirror mounts on the galvos with something to provide scale in the picture and a picture of your amp board. Any model numbers?

    Some GSI amps were interchangable for G330 and G120. Those that were interchangable could have larger caps fitted in the various filters and integrators to slow them down for g330s. If that is the case, your g120s would not tune up.

    I've never seen a closed loop gsi amp that WOULDNT do 12K min. Most did 20. What angle did you tune at?

    Steve Roberts.

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    Default G-120s

    I would say around 8 to 10 degrees, not a very big scan angle. I am using a modified sound card for my DAC (James's design). The main problem is, the amps are completely unmarked. No part numbers or even labels for the trim pots. I have found Gain and Offset, but I am kind of flying blind as far as Servo, HF and LF gain. After all of this, I think I am ready to just grab some other scanners that are a little easier to tune. I'll get some pics and post them once I take them. The PSU is one I built +/- 18VDC. My mirror mounts are probably on the heavy side. They are a clamp type (the mount fits on the shaft and is tightened by a small allen screw). The mirrors are probably heavy too, although, I have used mounts and mirrors this heavy before with a Laser Artestry amp and it did WAY better than this (around 15K at 15 degrees). Let me get some pics up and maybe someone on here might know what these amps are. Thanks Steve!
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    Since james code does optimization and doesnt do PPS (so I'm told) how do you know your sourcing the ILDA pattern correctly?

    Steve

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    Default pattern

    I ran it through Spaghetti as well. Points seemed tighter with spaghetti, but the image still didn't look good. As soon as my camera battery is done charging, I'll take some pics.
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    Default

    If you display the ILDA test pattern with Spaghetti you MUST turn blanking optimization off or the pattern will look completely messed up. If you try to tune with blanking optimization turned on it will never look right.

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    Default thanx

    Thanks Gary. Let me try again.
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    Default pix

    Okay, here are few pics.


    The mounts seem like they would be heavy. I am going to try and make some sleeve type mounts with a notch at the top to mount the mirrors. While I don't have calipers, the mirrors look to be 1mm thick:




    These amps were removed from medical equipment. this card had several different functions besides being a closed loop amp. It also drove a 4KHz GSI resonant galvo alnog with laser control. please note, I added the heatsink:



    Here is the other side of the board with the drive amps. I circled the only number that looked like a part number:
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    Default

    THE mounts and mirrors are fine in size. They look like NMLs old mounts. You could send them to Bill at pangolin and let him figure them out. He tends to do that for free, allowing for the cost of shipping. I'd probe around with a passive oscilloscope probe, find the output of the position demodulator op-amp, watch it on the scope and inject a 50 hz square wave until I figgured out whats what. I have no idea what the &^%$ heck those are from. They do not look like any of the standard GSI oem designs, nor even a reverse engineered one. BTW< the PA72 power stages cost a fortune, so those are not "cheap" designs

    Steve

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    Default Amps

    Actually, the drive amps are PA26 and yes, they way expensive. Mil-spec and I priced them at $150 each. That is, if you can even get them, they are obsolete. Based on what I found looking up certain parts, these amps should be fast. The PA26 is 18W per channel and specifically designed for motor control/servo use, not as an audio amp like most other closed loop amps. What makes this so difficult is the fact that there are multiple functions on the board. It shouldn't be hard to isolate the galvo amp portion though. I just need to spend more time checking it out. I am actually buying an 120 amp from Stanwax that I am going to use for the time being. I can normally find 120s pretty cheap. if I can figure this out, I will pick up another pair and use a dual head. I am going to shoot Pangolin Bill a message and see what he says.
    Those who fail to grasp art are the ones who criticize it.

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