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Thread: Medialas Microamp problem

  1. #1
    Join Date
    Sep 2006
    Location
    Netherlands
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    1,435

    Question Medialas Microamp problem

    Hi, I have a pair of micro amps connected to a pair of 6800's.
    Tuning them is not a problem and goes smooth.
    Only after a few minutes one of the drivers goes into a protect mode and switches off.
    At first briefly, later more frequent. The problem seems to worsen with complicated frames.
    The drivers are properly cooled on a large heatsink.

    It's NOT the galvo or the cable; I swaped them.
    It's NOT the power supplies, I checked and swapped them.

    I read somewhere the the microamp has some advanced protective circuitry, I suspect it to act too early.
    Can anybody confirm this, and how do I check if it works as supposed ?
    The board contains two small extra pots, does anyone know their function ?

  2. #2
    Join Date
    Feb 2007
    Location
    Herts, UK
    Posts
    1,254

    Default

    They have fuses to protect the galvo coil so maybe they don't have any advanced protection and you just have a dry joint or the TO-220's are not tight on the heatsink or something.
    Drop ML a mail and see what they say about it

  3. #3
    Join Date
    Jan 2009
    Location
    Germany
    Posts
    241

    Default

    Hi Bart,

    I had exactly the same symptoms, when I had my Microamps not enough cooled, so it might be a heat problem.

    Greetings
    Andreas

  4. #4
    Join Date
    Sep 2006
    Location
    Netherlands
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    Default

    Quote Originally Posted by p1t8ull View Post
    Drop ML a mail and see what they say about it
    I did a week ago, but as usual with ML the vast majority of my mails are bluntly unanswered.

    I'll take some look at the cooling of the individual components.

  5. #5
    Join Date
    Mar 2006
    Location
    Ottawa, Ontario, Canada
    Posts
    494

    Laser Warning

    Quote Originally Posted by -bart- View Post
    Hi, I have a pair of micro amps connected to a pair of 6800's.
    Tuning them is not a problem and goes smooth.
    Only after a few minutes one of the drivers goes into a protect mode and switches off.
    At first briefly, later more frequent. The problem seems to worsen with complicated frames.
    The drivers are properly cooled on a large heatsink.

    It's NOT the galvo or the cable; I swaped them.
    It's NOT the power supplies, I checked and swapped them.

    I read somewhere the the microamp has some advanced protective circuitry, I suspect it to act too early.
    Can anybody confirm this, and how do I check if it works as supposed ?
    The board contains two small extra pots, does anyone know their function ?
    Hi Bart,

    I also think it may be related to cooling. If you are using a Pangolin laser controller perhaps you can try running a test . Find a demanding complex graphics laser show (usually a raster based show) that really seems to trigger the shutdown of the Microamp galvo driver. After allowing the microamp to cool down and reset try running the same laser show but at lower frame rate to see If it makes any difference. I think the peak current extremes during high frame rates are causing the overheating and thermal shutdown. Try bolting them to a bigger heatsink and add a cooling fan.
    Profile Redacted by Admin @ 04.24.2010

  6. #6
    Join Date
    Sep 2006
    Location
    Netherlands
    Posts
    1,435

    Default

    I removed the pcb from its own heat-sink, preventively replaced the silicone slabs and re-did some solderjoints. Nothing obvious out of the ordinairy. Since I reassembled it, the problem has been gone.

    *keeps fingers crossed*

    Thanks all for your suggestions.

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