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Thread: Some scanner problem.

  1. #1
    Join Date
    Nov 2005
    Location
    Sweden
    Posts
    133

    Default Some scanner problem.

    I bought a Terrascan kit about a month before Christmas and now I hooked it up to my new Easylase unit. Now I have a problem with it. Everything looked like it was working fine then one channel started to act up and I had some sort of interference on that channel even when I had no output. I measured all input to the terrascan and everything looks OK. The signal is stable and so are the power at +-23 volts. Not even with the oscilloscope at maximum zoom I could pick up much interference or instability. I tried to output ILDA test pattern and I looked OK except for the interference. Then it happened. One channel dies and short after the other goes out. I double cheked the power and signal but everything looked fine.

    Any ideas on what could have gone wrong here?
    You know, I have one simple request. And that is to have sharks with frickin' laser beams attached to their heads!

  2. #2
    Join Date
    Jan 2005
    Location
    USA
    Posts
    457

    Default

    Double and triple check the wiring.

    With my Camtech scanners ive noticed that if i even put my hand within an inch of the galvos they will chatter and produce "static"...

    Isolate the wiring. double check to see if your amperage is fine, check the ohm count on the galvo signal wires.

    make an ILD file with a dot in the top right. then display it, see if the galvos jump any after a minute.

    unplug the galvos and measure the signal to the galvos.

    Im sure youve tried it, but check the temperature.

    Im not sure of the feedback system used on the terascan galvos... Unlikely: but maybe a photodiode is freaking out or getting too hot and falling out of tune...

  3. #3
    Join Date
    Jun 2005
    Location
    Los Angeles
    Posts
    263

    Default

    Check your fuses?

  4. #4
    Join Date
    Nov 2005
    Location
    Sweden
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    Default

    No fuses on the card. Strange really, you would have thought that they should put something there to protect the circuit.
    You know, I have one simple request. And that is to have sharks with frickin' laser beams attached to their heads!

  5. #5
    Join Date
    Nov 2005
    Location
    Sweden
    Posts
    133

    Default

    Just a little update if anyone is intrested. After a closer look and talking to the support at medialas I found out that there are micorfuses on the Amps. I changed the fuses and being a laze person i didn't drag all stuff over to my computer but instedd connected a laptop to the Easylase card. Everything works great. Of couse now I dont have any strange interferense. I found it strange that even the old problem with the interferens I had with my home made dac and the easylase was gone. I hooked it up to my stationary computer and there it was. Interferense again. I still dont know why but I'll look into it when I get home from work.


    I've got a friend that makes custom cases for a living. I hcalled in a favor and got this case made for the laser.


    A closer look at the mirror mounted inside the case.


    Here on the back I'll put in a couple of Neutrik connections, USB and power.


    One of these for the Easylase card.
    http://www.neutrik.com/images/ock/su...1440392726.jpg

    I't easy access to the laser from behind.


    The two boards runs on a track that holds everything in place.


    When I moved the powersuply to the bottom board I go lots of room for a red laser and hopefully a blue sometime in the not to distant future.
    You know, I have one simple request. And that is to have sharks with frickin' laser beams attached to their heads!

  6. #6
    Join Date
    Jan 2005
    Location
    Norway
    Posts
    1,302

    Default

    like it
    That is a sweet little box

    I also need to find myself a box to put my stuff into...
    But i think i want a alu box (like the one FBI folx uses hehe)



  7. #7
    Join Date
    Jan 2006
    Location
    PARIS
    Posts
    125

    Default

    be sure to have the ground connected to ALL systems between the computer, DAC etc...even the scanner amplifier.
    i have some trouble with systems connected without ground. you can check this with a multimeter in AC voltmeter mode
    if you have 60VAC between the computer and other equipments you have a ground problem and you can have some troubles with scanners etc...
    the 60VAC was caused by the input filter in power supply.
    you have three X2 condensators
    one between live and neutral one between ground and neutral and the last between live and ground.
    but at 60Hz a condensator have a impedance and if the ground is disconnected you have a voltage divider between neutral and live with the ground connection for the output. and 120v/2 is 60Vac

  8. #8
    Join Date
    Nov 2005
    Location
    Melbourne, Australia
    Posts
    3,693

    Default

    This interference you speak of is almost certainly ground loop induced noise.

    Does the scan amp have differential inputs? If so, a ground connection to the scan amp is not really needed.

    To prevent ground loop problems, each component in your system should only have one path to ground.

  9. #9
    Join Date
    Mar 2006
    Location
    East Coast , Canada
    Posts
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    Default

    Oh YEa, this Has to be a ground loop... the last arena show i did, This reared its ugly head.....Put the projector and computer on the same circuit and BOOM! All gone!
    CREATIVITY AT THE SPEED OF LIGHT!
    www.laser-ad.com

  10. #10
    Join Date
    Jan 2006
    Location
    PARIS
    Posts
    125

    Default

    all grounds of all systems need to be connected in no balanced mode. without this connection you can destroy scanners and others! (personnal experience inside)
    the best solution is balanced signals for the scanners
    (remember that the 0v of a power supply inside a computer is directly connected to the ground and the case of the PC)

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