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Thread: Lightwave Halfnote Green Laser Questions

  1. #71
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    Sep 2006
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    2 should be connected to gnd
    6 should be connected to +5v
    4 needs +5v to reset faults,
    28 sets the current, 10A should get you some lasing output, 50A is not possible.
    Best measure the current with a dc current clamp.

  2. #72
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    Aug 2016
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    Quote Originally Posted by -bart- View Post
    2 should be connected to gnd
    6 should be connected to +5v
    4 needs +5v to reset faults,
    28 sets the current, 10A should get you some lasing output, 50A is not possible.
    Best measure the current with a dc current clamp.
    Thank you -bart-

    Okay I try it 28 setting by 0-5V?
    what about 8pin? the same? 0-5V?


    10A is enough in the beginning
    I think of another power supply or modifications to be able to give 25-30A (original power supply is 50A)
    Of course if I get to the appropriate control TEC for KTP and diode.

    I still have doubts, manual says -3.3V for the laser, OK but for example ebay seller showed the pictures that connected the green cable to the positive and the black to GND and laser work. Quite the opposite than original circuit. I think as it can be. So when use other external power supply, you need to replace power poles ??? Sorry for this question but now I'm not sure about connection with other PSU, even original without Analog PCB.

    Thanks for tips.

  3. #73
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    The driver needs minus 3,3V. because the anode of the pump diode is connected to gnd.
    Do you have the service manual ?
    There are many inputs/ways to set the current, even with the light-loop, pin 8 is the "proper" way to set the current, I believe.

  4. #74
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    Aug 2016
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    Yep that it is with "original" circuit. But I wondering about other ways to powering halfnote heads. I just got service manual and will reading all.

    Quote Originally Posted by -bart- View Post
    The driver needs minus 3,3V. because the anode of the pump diode is connected to gnd.
    Do you have the service manual ?
    There are many inputs/ways to set the current, even with the light-loop, pin 8 is the "proper" way to set the current, I believe.

  5. #75
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    Aug 2016
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    I did everything as it should be, and the laser doesn't start
    I don't have the power at P3 :\
    I did a search at analog PCB and found that in the section Diode P.S Crowbar the thyristor is blown (TH1 MCR69-1) In the measurements it pierces in every direction. I don't have MCR69-1 replacement but the equivalent of 2N6507 will be good I think.
    Tomorrow I fix it and further can finally laser light.

  6. #76
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    Aug 2016
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    I have a light !! but... after about 3 minutes work, power decreases and the laser is switched off.
    Doing measurements on TP26, I noticed when the voltage drops below 1,61V, laser light dramatically low and the laser stop working.
    The voltage drops down even -3.3V at TP26.

    Unit need for a few minutes of rest, reboot and laser working again, TP26 is again 1.81V, the laser shines very well. The situation is repeated, the voltage drop and the laser turns off.
    I think the problem is with the circuit "Diode Shutoff". The Q1 (gate) voltage grows and runs "Diode Shut Off"

    When I cut track of Q1 (gate) the problem will disappear. In this way, I "turned off" the "Diode Shutoff"
    Now it seems to work OK.
    Pin 8 I have set to 5V. (Max current for diode)
    This sets voltage at TP26 to a maximum of 1.81V, so that at P3 I got -1.8V (maximum).
    So theoretically, if I increase the control voltage for transistors from 1.8V to 2.5V for example, then P3 should reach the level of - 2.49V and more Ampers = more power for the laser Diode should theoretically pull up 25A at -2.5V easily.

    To sum up:
    I think that it is possible to obtain more power by increasing the voltage to the control transistors, above 1.8V.

    During the tests, TEC controller work properly, also KTP.
    Head temperature has not increased dramatically and was around 34 degrees on the heat sink.
    Laser start up when the watchdog is 200Hz and even when set to 500Hz works too. (500Hz was written in the manual)
    Pin 8 I have set 5V (below 3V laser off)
    Pin 2 and 6 to GND.
    Pin 4 to + 5V.

    Voltage measurement at P3:
    -1.6V is the threshold laser operation.
    -1.8V laser shines beautifully, burns easily black materials.
    I don't have a power meter at the moment, so far I can't say how much Watts is output. (Sticker says that my laser has a 3.5W
    At the moment unable to go up above - 1.8V at P3.
    I will to get around to squeeze maximum power from head.

    The laser was turned on over 3 hours, and everything works well.



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    Last edited by Diodac; 09-02-2016 at 06:22.

  7. #77
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    Aug 2016
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    I made a deeper analysis and thought that it can be modified - easy. You do not need a watchdog, PAL interlock IC and a few other things that limit the use of the laser at full power. Besides TTL modulation it is useful. So I have modified all for my needs, adjusted the new temperature for the diode and KTP, add TTL option, own circuit protection, trehold current for diode during TTL, ect. I added even scanner
    Now I can easily squeeze even 40A, 3.5 watt power laser etc.
    How I find a moment, I write the exact tutorial what must be done and give diagrams modifications.

    Now a short video of the first results.


  8. #78
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    Aug 2005
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    Impressive. I still have a few of the half-note lasers here. I'm looking forward to seeing how you did this and trying it myself.

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