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Thread: Need help identifying and tweaking a DPSS

  1. #1
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    Default Need help identifying and tweaking a DPSS

    During a shelf cleaning I found a small Showtec DMX laser projector. It was advertised as 30mW of 532nm green in the folder, however, there were no direct power indications on the box as far as I can tell. Only warning stickers stating 'Class 3B'. The manual can be found here:

    http://www.csi-france.com/telecharge...%20G-30_en.pdf

    I decided to take my chances as the unit was only collecting dust (I pretty much rendered it usesless), and took off the cover. Just as curiosity to see what's inside and whether I could possibly re-purpose this unit for a compact single color projector.

    Much to my surprise, I inspected the driver board and found the head had a connector that lead to a TEC, and read the sticker on the actual laser head. It had a sticker reading a maximum power of 300 mW (no, that's not a typo, it says three HUNDRED, not THIRTY).

    So the goal here is obvious: I'm looking for a way to crank this thing up from 30mW to the 300mW it should be able to make. Even if I can get half of it out (150mW) I would be happy with it.

    The laser itself looks pretty solid and I suspect it's an OEM unit. It has an AC input from a transformer underneath the stepper driver board, a modulation input (which I don't know whether it's active high or low) and a connector leading to the head. Aside from that, it has a set of 2 precision pots, which I suspect control power (current) and TEC target temperature.

    I'm afraid of tweaking if I don't know where to look because I would hate to damage the head. Photos of the laser projector and head (including sticker close-up) are attached.

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  2. #2
    swamidog's Avatar
    swamidog is offline Jr. Woodchuckington Janitor III, Esq.
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    those stickers are meaningless. ignore them.

    most likely you will succeed only in letting the magic smoke out of your laser.

    Quote Originally Posted by Stoney3K View Post
    During a shelf cleaning I found a small Showtec DMX laser projector. It was advertised as 30mW of 532nm green in the folder, however, there were no direct power indications on the box as far as I can tell. Only warning stickers stating 'Class 3B'. The manual can be found here:

    http://www.csi-france.com/telecharge...%20G-30_en.pdf

    I decided to take my chances as the unit was only collecting dust (I pretty much rendered it usesless), and took off the cover. Just as curiosity to see what's inside and whether I could possibly re-purpose this unit for a compact single color projector.

    Much to my surprise, I inspected the driver board and found the head had a connector that lead to a TEC, and read the sticker on the actual laser head. It had a sticker reading a maximum power of 300 mW (no, that's not a typo, it says three HUNDRED, not THIRTY).

    So the goal here is obvious: I'm looking for a way to crank this thing up from 30mW to the 300mW it should be able to make. Even if I can get half of it out (150mW) I would be happy with it.

    The laser itself looks pretty solid and I suspect it's an OEM unit. It has an AC input from a transformer underneath the stepper driver board, a modulation input (which I don't know whether it's active high or low) and a connector leading to the head. Aside from that, it has a set of 2 precision pots, which I suspect control power (current) and TEC target temperature.

    I'm afraid of tweaking if I don't know where to look because I would hate to damage the head. Photos of the laser projector and head (including sticker close-up) are attached.

    Click image for larger version. 

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ID:	22163Click image for larger version. 

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ID:	22164Click image for larger version. 

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ID:	22165
    suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.

  3. #3
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    You should do your homework better concerning wishful-thinking-max-power-labels !
    99% chance that the manufacturer already pushed it to its max.

    Considering that it's a 30mw model, it probably doesn't even have a TEC.

    My advise: rip out the dpss, scrap it, replace it with a 445 diode.
    With some luck you can recycle the driver.

  4. #4
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    Quote Originally Posted by swamidog View Post
    those stickers are meaningless. ignore them.

    most likely you will succeed only in letting the magic smoke out of your laser.
    I know I shouldn't take the sticker powers that seriously. But I doubt a 30mW DPSS laser would need TEC cooling? I had a 50mW DPSS head from Dealextreme (a cheap New Wish laser) and it wasn't even fan cooled.

    Manufacturers that repurpose their components for different products are not uncommon, so I hope I can squeeze a few more mW out of this unit.

    The modulation input is active low and, I suspect, TTL. I disconnected the controller and the head started up CW. No output delay on the driver itself.

    Quote Originally Posted by -bart- View Post
    Considering that it's a 30mw model, it probably doesn't even have a TEC.
    It actually *has* a TEC, which is wired up to the head. Pinout is +TEC, GND, Thermistor +, Thermistor -, LD+, LD-. There are also a few beefy semiconductors on the unit, a TIP122/127 combo (possibly driving the TEC in push-pull mode) and an LM317 (which I suspect regulates the LD current).

    My advise: rip out the dpss, scrap it, replace it with a 445 diode.
    With some luck you can recycle the driver.
    That's my backup plan, since I can always rip out the DPSS if I kill it. A 30mW DPSS is kind of useless for a serious projector anyway, only maybe as a gimmick for birthday parties.

    One thing I do find surprising is that there is no indicated power on the *outside* of the projector's casing. And if the head is stickered as 300mW, isn't it illegal to write a lower power value in the manual? The sticker on the head is supposed to show the maximum possible power, including IR leakage.
    Last edited by Stoney3K; 12-09-2010 at 09:02.

  5. #5
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    OK, small-ish update here:

    The laser is driven from an OTA feedback loop driving one of the transistors. The other end is probably used by the TEC.

    There's a 4-ohm monitor resistor in series with the laser diode. I managed to max out the current on the driver at 600mA, unfortunately the pot won't go any further.

    I can't determine the actual output but the laser appears to be somewhat brighter. I might have a go at replacing the driver or increasing the supply voltage to get to at least 1A on the pump diode. (If I break the laser in the process, I could care less and it means I've got a great TEC-cooled box for a 445.)

  6. #6
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    Sorry to dig up this thread, but how did this little 'experiment' turn out?
    I'm curious because after repairing several showtec shogun lasers, it seems that this same head is used in lasers from 30mw up till 200mw versions (eg the shogun rgb pro 500).

  7. #7
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    Quote Originally Posted by jeejeedr View Post
    Sorry to dig up this thread, but how did this little 'experiment' turn out?
    I'm curious because after repairing several showtec shogun lasers, it seems that this same head is used in lasers from 30mw up till 200mw versions (eg the shogun rgb pro 500).
    I haven't modified the laser so far, but have been running it at its maximum current ever since I salvaged it, without any decrease in (visible) output.

    When experimenting I did notice the laser was perfectly capable of vaporizing some black gaffer tape, indicating its power output would be far greater than 30mW, but I suspect most of it is stray IR and not visible green.

    If the same head is also used in the higher power versions, chances are the only difference is the supply voltage. If you have the lid off an RGB 500, can you measure the input supply voltage for me? On the G-30, the board is powered by 2x9V AC.

  8. #8
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    in progress of buying an old one. If I can buy it (cheap) then I'll do the measurements. For the moment I only have an rgb 250 here.

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