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Thread: Laserpic scanner failure

  1. #1
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    Default Laserpic scanner failure

    Background:
    Today…I was doing a final alignment adjustment of the scanner head on my projector. This adjustment required a slight movement of the entire scanner head to achieve best placement for the incoming RGB beam. The scanner power supply was off. The scanner head was unbolted and removed and the position hole was enlarged to allow for better alignment of beam to X/Y Galvo mirrors. All went well. The scanners are Laserpic LP 30’s.
    Prior to this point in time…when the Scanner PS was powered up…the galvos would center their orientation….and the RGB beam would project very close to a 90 degree from both the X and Y galvo axis. When the scanner power was turned off…the galvos would go to a “ default position” …not at the 90 degree…..but always the same position. When the scanner was on… BOTH red LEDS on the scanner amplifier boards would illuminated…solid red( NO FLASH )…and the green LED on the 24VDC power supply would also light up solid (NO FLASH )
    Problem:
    After the re-alignment was complete…I went to power up the scanner PS…Now……the Y-Galvo was NOT stationary….as it had operated before….now it has a chatter/movement….about every one (1) second….the Y-Galvo rotates…about 30 degree….up and down….and just keeps this movement up….shifting about every second. And now…The red LED flash on BOTH scanner amplifier boards…their flash rate is in sync with the Y-galvo movement and the green LED on the PS also strobes in sync with the red LED’s. Oh….I observed NO magic smoke puff when the scanner was powered back up !!!!
    Trouble shooting:
    I tried to determine if my problem was with the Y-galvo. To this end…I exchanged X/Y galvo hook-up to the scanner amplifier. This had NO effect. Either galvo has the same unsolicited movement when connected to the Y scanner amplifier board. Another notable fact…when I disconnect the galvo from the Y amplifier board…..the red LED indicator lights go back to solid red illumination and the green PS also is on solid. As of this time….I would say there is a problem with my Y amplifier board…..What caused it and why did it happen when I moved the scanner head ????? ….Dunno ???. ALL Aluminum drill chips were contained and collected with great care !!! I likely did something wrong ???? Was the projector grounded when the drilling operation was going on ???? mmmmm…..I THINK it was ?????
    This unit is long out of any type of warranty !! Can it be repaired ??? Maybe !!! Is there anything or connection I should check ??? Ground to the PS is good… It is a real pisser when I just now have started “ swinging the beam”…… and the “ swinger takes a crap” !!!!....Or…..Should I just use this as an excuse to pop for a new DT-40W ( That’s what TerraWatt sez…..and she is almost ALWAYS right !!!!!!! )….and to that end…..what does everyone think about DT scanners ??????? THANX !!!! Bob.....OH...I have emailed Laserpic....No response yet....
    Last edited by CDBEAM; 01-03-2010 at 05:02. Reason: typo
    Beam Axiom #1 ~The Quantum well is DEEP ! Photons for ALL !!
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    Beam Axiom #2 ~Yes...As a matter of fact...I DO wear tinfoil on my head !!
    .
    Beam Axiom #3 ~Whe'n dout...Po ah Donk awn et !!
    .
    Beam Axiom #4 ~A Chicken in every Pot, and a Laser Lumia in every Livingroom !!
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    Beam Axiom #5 ~"Abstract Photonic Expressionism"....is "Abstractonimical" !!
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    Beam Axiom #6 ~ "A Posse ad Essea" ~ From being possible to being actual ...is the beam target !

  2. #2
    Join Date
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    Monroe, Mi USA
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    Default Bottom Line

    DT scanners......current general opinion ?????...Thanx
    Beam Axiom #1 ~The Quantum well is DEEP ! Photons for ALL !!
    .
    Beam Axiom #2 ~Yes...As a matter of fact...I DO wear tinfoil on my head !!
    .
    Beam Axiom #3 ~Whe'n dout...Po ah Donk awn et !!
    .
    Beam Axiom #4 ~A Chicken in every Pot, and a Laser Lumia in every Livingroom !!
    .
    Beam Axiom #5 ~"Abstract Photonic Expressionism"....is "Abstractonimical" !!
    .
    Beam Axiom #6 ~ "A Posse ad Essea" ~ From being possible to being actual ...is the beam target !

  3. #3
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    Default

    Quote Originally Posted by CDBEAM View Post
    DT scanners......current general opinion ?????...Thanx
    DT Scanners are very good.
    http://img62.imageshack.us/img62/3985/laser.gif

    Doc's website

    The Health and Safety Act 1971

    Recklessly interfering with Darwin’s natural selection process, thereby extending the life cycle of dim-witted ignorami; thus perpetuating and magnifying the danger to us all, by enabling them to breed and walk amongst us, our children and loved ones.





  4. #4
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    Default

    Just a couple of ideas.

    Always start with the power supply. IF you have a scope take a look at the + and - dc supply to the scanners.
    If that is fine. Then disconnect power to one scanner and see if that is doing strange things. Then do the same with the other.
    Be sure to have the DAC disconnected when you do this. If the problem goes away then the dac is bad.

    Take your scope and look at the dac output for x and y to make sure the dac is not getting flaky.

    The other thing you might want to do is mark the position of all the trim pots on the drivers and turn them back and fourth a couple of times maybe you have a scratchy pot.

    If all of that fails then it is time to Upgrade!

    chad


    When the going gets weird, the weird turn pro.


  5. #5
    Join Date
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    Default The Master Plan

    Well....I wish I did have a scope......it does seem odd that the output of the Y scanner amp ONLY goes Goofy WHEN ....either galvo is connected. My "uneducated in electronics" brain sez that WHEN a galvo is connected to the Y scanner amp......something is NOW shorting out in some kinda cycle loop on the Y amplifier board. This cycling ONLY happens when a galvo is connected....and kicks out the PS.....which then shuts down the PS.....the short is now gone....the PS goes back on...and the whole cycle starts over !!!! Thanx for the info....and I will fiddle/diddle with the pot trimmers.

    I quess I have 99% made up my mind to have LP replace the board......and use the LP scanner for a stand alone Green Projector (hehe....we know this will evolve to a RGB at SOME future point )....and go with the DT-40W....at that wide an angle....it is like getting two more projectors....one the left and right.

    mmmmm, TerraWatt sez : Cross your T's and Dot your Quantum I's.....
    Thanx !!
    Bob
    Last edited by CDBEAM; 01-03-2010 at 12:20. Reason: Brain problem
    Beam Axiom #1 ~The Quantum well is DEEP ! Photons for ALL !!
    .
    Beam Axiom #2 ~Yes...As a matter of fact...I DO wear tinfoil on my head !!
    .
    Beam Axiom #3 ~Whe'n dout...Po ah Donk awn et !!
    .
    Beam Axiom #4 ~A Chicken in every Pot, and a Laser Lumia in every Livingroom !!
    .
    Beam Axiom #5 ~"Abstract Photonic Expressionism"....is "Abstractonimical" !!
    .
    Beam Axiom #6 ~ "A Posse ad Essea" ~ From being possible to being actual ...is the beam target !

  6. #6
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    Native Floridian
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    Default

    Regarding the DT-40W's, geez, I've never seen anything like these. I just fired up the first set, using the "Orientation" test frame. About 4 feet from the scanners the test pattern is touching my ceiling and floor. I can say the the scan head is probably going to need to be attached to a thick metal plate for good heat sinking as they get very warm. I'll have more to report soon.

  7. #7
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    Default

    Hey David...

    Does CDBeam's problem sound familiar? Because it should... My scanners were doing EXACTLY the same thing back in 2008, and we traced the problem to a 5 volt short to the ground plane, remember?

    It was a really subtle thing. Sometimes the scanners would power up and be fine, but other times they'd tick back and fourth about once a second, just like CDBeam's scanners are doing...

    The problem turned out to be a worn piece of mica on a power transistor for the green laser driver. It was supposed to insulate the transistor from the heat sink (which was grounded to the case), but it was making intermittent contact.

    Anyway, CDBeam: check the grounds on your projector to see if you have any voltage relative to earth ground. (In theory you should have all grounds tied together, but lots of people wire their projectors differently.) Also check them against pin 25 on the ILDA cable. Everything *should* be at the same potential, but in my case the transistor on the driver was leaking +5 volts into the projector grounds, causing signal interference with the galvo amps. You may be experiencing the same thing.

    Adam

  8. #8
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    Default

    As this problem started after you drilled the baseplate with the amp installed; logic would say that your short is going to be swarf. Check again.
    http://img62.imageshack.us/img62/3985/laser.gif

    Doc's website

    The Health and Safety Act 1971

    Recklessly interfering with Darwin’s natural selection process, thereby extending the life cycle of dim-witted ignorami; thus perpetuating and magnifying the danger to us all, by enabling them to breed and walk amongst us, our children and loved ones.





  9. #9
    Join Date
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    Monroe, Mi USA
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    Default " Dis'a'semble ?? NO Dis'a'semble Johnny 5 "

    Well....just an update...Laserpic has responded in a more than fair fashion !!! They will replace the Y scanner amp board....FREE !!!!......I have to tear it ALL apart ...to see what gives.....thanks for your help !!!!!
    Bob
    Beam Axiom #1 ~The Quantum well is DEEP ! Photons for ALL !!
    .
    Beam Axiom #2 ~Yes...As a matter of fact...I DO wear tinfoil on my head !!
    .
    Beam Axiom #3 ~Whe'n dout...Po ah Donk awn et !!
    .
    Beam Axiom #4 ~A Chicken in every Pot, and a Laser Lumia in every Livingroom !!
    .
    Beam Axiom #5 ~"Abstract Photonic Expressionism"....is "Abstractonimical" !!
    .
    Beam Axiom #6 ~ "A Posse ad Essea" ~ From being possible to being actual ...is the beam target !

  10. #10
    Join Date
    Nov 2007
    Location
    Cairns, Australia
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    1,896

    Default

    Good to see you found a fix. For future reference, when a switchmode power supply blinks it's LED like that, and everything else blinks with it, it usually always means that it has a dead short somewhere. It pulses the power to check if the short is gone, if not, it turns off, waits a few milliseconds and tries again, that is the pulsing you see.

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