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Thread: Oscillating on axis after warm up

  1. #1
    Join Date
    Dec 2011
    USA California

    Default Oscillating on axis after warm up

    I have a Dt-30 set from Dave that had been working awesome until i noticed slight wobbly images, i figured a dc ground connection came lose.
    I took it apart, tightened screwed conections and soldered connections that i had connectors on, and fired it up.
    SOLID frames no shakes or bearly noticeble wobbles..
    3 minutes after running flawless it came back.
    I drove myself mad thinking it was a ground connection that i was not making, or a scanner driver over heating or ground loop.
    After attempting "different grounding schemes" thinking i wired it wrong it would make my image worse or back to the original issue.
    I later isolated the +/-24v PSU, motors, and driver boards from the system and shined a beam on to the mirrors and still oscilates a few minutes after being turned on for a few minutes without anything connected to its signal inputs.
    I swapped one end of each x/y cables and noticed the oscillating swapped axis so i narrowed it to the X axis board.

    I am familiar with the power and signal wiring but nothing when it comes to troubleshooting or tuning boards.
    I am posting this in hopes someone can steer me in the right direction to figure this problem out. I know its a long shot since this forum is way quiter than i remember and alot of old friends from here have moved on from this page/diy.
    I will continue to research but i feel like I've hit a road block with this one.
    Thanks for any input.

  2. #2
    Join Date
    Jan 2014


    if you short-circuit your input, then the x-axis still vibrates ?
    Maybe the driver for the galvo is set too fast.
    But it would also be possible a bearing damage from the galvo. But swapping x y does not just work, you have to readjust the drivers.
    There can be multiple causes for this. I assume that the electrical wiring is correct.

  3. #3
    Join Date
    May 2007
    1 hr from everything in SoCal


    I would also say it might be a polyswitch triggering as it heats up but that normally distorts the image (power limiting) on one axis, not normally a wobble. Still, might be worth checking. Try scanning at a low angle see if it happens still. If you have a temperature gun or FLIR, I would check the temps on both scanners and drivers. If it is fine when the kit is cool and then gets worse as things heat up, I am less inclined to think it's a grounding or wiring issue. Might wan't to also try cold spray on the driver components.

  4. #4
    Join Date
    Jan 2006
    Charleston, SC


    You've already done a great job troubleshooting this problem! However, I think you're overlooking a key piece of information from your original post:

    Quote Originally Posted by ADROIT View Post
    I took it apart, tightened screwed connections and soldered connections that i had connectors on, and fired it up.
    SOLID frames no shakes or barely noticeable wobbles..
    3 minutes after running flawless it came back.
    So it *was* flawless, and then after 3 minutes the wobbles came back. Crucially though, the wobbles came back without any further action on your part. Thus, it's an intermittent problem.

    This means it's not a tuning problem, because it would be bad all the time if the tuning was off. It's not a ground loop, for the same reason. It could be a loose wire, but you checked everything and re-tightened all the connections, so that is highly unlikely at this point. And a failed poly-switch will normally cause the affected axis to completely collapse, not just wobble, so that's equally unlikely to be your problem. (You could easily short around the poly-switch just to rule this out, however.)

    In my opinion the most likely source of your problem is a cold-solder joint somewhere on the amp. Another possibility might be a bad trace on the board. Unfortunately both of these flaws will be very hard to find. You may want to poke around on the board with a hot soldering iron and see if you can find any bad connections. If you've exhausted all other options, you can even try baking the board in a re-flow oven and see if that helps.

    But unless you're driven to find and fix the problem as a matter of principle, honestly it's probably better to simply replace the amp at this point, if not the entire set of scanners.


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