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Thread: Post Projector Construction Issues....

  1. #1
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    Angry Post Projector Construction Issues....

    Well, I finally have everything properly mounted and now I'm running into issues. first thing that happened is the red laser diode burned out and now just glows a dim red. I think this happened when the laser touched the grounded chassis, I don't know why, but it did! Anyone have a 100mW 650nm diode they can sell me? Just the bare diode, no optics needed. Other than that I ran the completed projector with the green laser only and it worked fine. This morning I go to run it again and the green laser isn't working! I have narrowed it down to the TTL on the driver itself. Whenever the TTL connection is plugged in the whole driver just shuts off. The laser works fine with the TTL unplugged but ofcourse no blanking. Any suggestions as to where I should start to fix this issue?
    Thanks!
    Adam

  2. #2
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    Lightbulb

    TTL isn't wired backwards is it? Basics first.
    Love, peace, and grease,

    allthat... aka: aaron@pangolin

  3. #3
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    Quote Originally Posted by allthatwhichis View Post
    TTL isn't wired backwards is it? Basics first.
    Hi,
    Yeah, it's wired right. It worked last night and the wiring didn't change. Though, I did check it with my scope meter a minute ago and verified the voltage is not reversed.

    Another thing that could have caused this problem is the power cord I am using. It's (I believe) euro color codes. I assumed blue is hot and brown is neutral. It seems that blue is neutral and brown is hot. Can anyone confirm this and would this cause my mishaps? If so, it didn't change anything. I swapped them and am still having problems.
    Thanks!
    Adam

  4. #4
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    On Euro mains leads Blue is neutral and brown is Live (and cheese and onion is earth ).

    Are both the lasers grounded to the grounded chassis? If so this is likeley to be wrong! As a general rule DPSS pump diodes are anode to the case but dvd diodes - which im sure is what yours is - are cathode to the case. This means that its best to isolate one or both of the lasers from the chassis - thats how mine is done - but ground the chassis and the laser sources (or their power supplies) properly.

    Dont assume you lasers are the way I have said - test them so you know for sure if their cases are 0v or supply volts.

    What sort of driver does you red diode have and what protection does it have for noise and over volts on supply and TTL etc? Diodes are very very sensitive and will pop if you look at them in a funny way so you need to treat them with the utmost care. When they are wired to a driver they will be less prone to death by static but prone to other death threats such as power line noise/spikes.

    Have you removed the lasers from the projector and tested them in isolation of the rest of the machine?

    Rob

  5. #5
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    I have a 170mW red diode without optics to sell, coming from my old MAXyz module. No more than 100 hours of use, so quite new.
    PM me if you're interested

    Seb

  6. #6
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    As stanwax said, be very careful with those grounds. I had some grounding issues but luckily nothing blew. I bought some 3"x5" mica sheets that I use to isolate my green laser from the baseplate.

    I probably know what happened to your diode. If you take a look at the die4drive schematic (www.die4laser.com) you can see that the cathode is not at ground. But, the case of the red diode probably was connected electrically to the cathode. So when you grounded out the case on your plate you added an extra volt or two to the diode and WHAMO! You just turned your 100mw laser into a 300mw laser for a split second. Even if you didn't use the die4drive driver (not saying you did) I bet that it is the same problem.

    This is a lesson for everyone fooling with metal base plates and/or multiple lasers/equipment.

  7. #7
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    Good News!
    Somehow the TTL on my green DPSS started working again! Yay! One less thing to worry about. It kinda scares me that I don't know what caused it but it looks like I didn't blow anything. My RGY projector should be done shortly.
    Thanks!
    Adam

  8. #8
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    GROUND NOTHING!!
    This isnt going to be taken well by electrical conservatives, but I've found it to be good. Although a "kelvin connection" if needed above ground is good for noise issues. And the chassis to earth but only if no PS is connected to chassis. But SAFETY FIRST!! So, where applicable ignore this! (disclaimer) heh
    (I've blown a few scope ground probe leads as well as some of y'all I'm sure with ground issues)

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