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Thread: Problem with projector.

  1. #1
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    Default Problem with projector.

    Dear all,


    I have a progblem with one of my DIY projectors. (Galvo Set PT-A40).
    when I introduce an image to it, shows as deformed (smaller on the center and with lines that should not apear conecting these different images, as you could see on the sample image.

    Correct image:
    http://i66.tinypic.com/fcplyo.jpg


    Image with problems:
    http://i64.tinypic.com/i1leon.jpg


    Someone know what happens and why it is caused?

    Thank you.
    Best regards.

    Juanma.

  2. #2
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    Default

    Please tell us more about the diode modules, PSUs, and other electronics in the build. Pictures of the build would be useful too. Iím guessing you have a rouge electrical problem resulting in a charge to your optical plate thatís screwing with multiple drivers and the galvo signal. I most commonly see this due to ungrounded inputs to the PSUs or faulty (like poor quality Chinese) PSUs. There could be two problems as well like poorly set bias and a signal issue to the galvos. More details are necessary to guide further.

    David
    "Help, help, I'm being repressed!"

  3. #3
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    Hello, thank you very much for your help.
    Tomorrow I try to answer your questions.
    I also think it's a connection problem, but I can not find the solution.


    I have connected AC ground (all power supply) to chassis (base).
    Negative DC (all) to ILDA pin 25.
    Between AC ground and DC negatives, there is no continuity. But when I connect network cable (AC 240v) ... between AC ground and DC negatives if there is continuity !!!.
    This is normal?


    Projector DIY:




    Thank you.

  4. #4
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    Default

    We are happy to help here, Juanma!

    Thank you for the additional information. From the picture, it is clear that there is not a bias setting problem, because none of your drivers have bias settings.

    Quote Originally Posted by juanma666 View Post
    I have connected AC ground (all power supply) to chassis (base).
    Good, but they should all be tied to the baseplate in a single location. This article by Bill Benner explains how your projector should be wired. One difference for you is that you have a +/-24V PSU for your scanners, so you don't need to do the connections between two +24V PSUs as described in this article.

    Negative DC (all) to ILDA pin 25.
    In many cases you don't need to tie anything to pin 25. Occasionally, you can tie your ground wire from your galvos to pin 25, but it is better practice to leave the signal ground for your galvos disconnected from everything. I would advise you to disconnect your negative DC from pin 25.

    Between AC ground and DC negatives, there is no continuity. But when I connect network cable (AC 240v) ... between AC ground and DC negatives if there is continuity !!!. This is normal?
    No, it is not normal. If disconnecting DC ground from pin 25 doesn't work, you have a problem with one of your drivers or one of your PSUs. Eliminate the drivers by disconnecting power one at a time and watch what happens. If that doesn't identify the problem, then you should replace the PSUs one at a time with another to see which one is bad.

    Good luck!

    -David
    "Help, help, I'm being repressed!"

  5. #5
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    Hello, David.
    Thanks again; I will do what he tells me and I will tell him.

    I have been able to verify that when connecting AC 240v cord ... there is continuity between AC ground and negative DC, caused by USB (external sound card CAKEWALK UA-25EX by Roland) that I use to connect hi-fi equipment to the same computer as laser projectors for laser show with music, with Spaguetti program.
    This is a problem?


    But other projectors (4) work normally.




    Best Regards.
    Juanma.

  6. #6
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    With multimeter in continuity mode (beep) ... dials 168 or -168 depending on polarity and beeps.
    Does it mean that HI-FI equipment puts current in projector?

  7. #7
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    Try grounding pin 25 to the chassis of the projector/DB25 case, assuming your DC grounds are connected to pin 25
    http://www.facebook.com/SubsonicSystems
    http://www.frikkinlazors.co.uk

    You are using Bonetti's defense against me, ah?

    I thought it fitting, considering the rocky terrain.

  8. #8
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    Quote Originally Posted by juanma666 View Post
    With multimeter in continuity mode (beep) ... dials 168 or -168 depending on polarity and beeps.
    Does it mean that HI-FI equipment puts current in projector?
    Have you tried to use this equipment with your other projectors? If yes and it is only happening on this one projector, then your problem is not that. Then you can try my earlier suggestions and Nortyís also. Please tell us the effect of each change.

    Kind Regards,

    David
    "Help, help, I'm being repressed!"

  9. #9
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    Hello.


    Yes, there are five projectors connected to the sound system.
    The rest of the projectors work correctly, I only have a problem with this projector; I will test what you say and what advises Norty and I inform you.
    The shows that I play, I add them with the five projectors ... each one does their work.

    This Sunday I try to do the tests and I will inform you of the results.


    Thank you very much.



    Best regards.
    Juanma

  10. #10
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    Quote Originally Posted by dkumpula View Post
    In many cases you don't need to tie anything to pin 25.
    While I agree with this (because many controllers internally ground the negative color modulation signals to pin 25 anyway), I also feel that it's a good practice to connect pin 25 to your projector ground nonetheless.

    Occasionally, you can tie your ground wire from your galvos to pin 25, but it is better practice to leave the signal ground for your galvos disconnected from everything.
    I disagree here. You really *don't* want to ground the input to your galvos. That's the exact condition which leads to the signal artifacts described in Bill Benner's article about projector wiring. You should only have X+ and X- connected. Do not connect anything to the signal ground.

    Quote Originally Posted by juanma666 View Post
    there is continuity between AC ground and negative DC, caused by USB (external sound card CAKEWALK UA-25EX by Roland)
    This is not surprising. I have encountered several cases where the ILDA pin 25 ground is connected to AC ground at the host computer. But since all of your projectors are connected to this computer, they should *all* show the same continuity. Your post above seems to suggest that only this one projector shows continuity between the AC and DC ground. If that is the case, then the continuity isn't coming from the sound card...

    Quote Originally Posted by juanma666 View Post
    With multimeter in continuity mode (beep) ... dials 168 or -168 depending on polarity and beeps.
    Does it mean that HI-FI equipment puts current in projector?
    No, it means that the DC ground on the computer (which includes the USB port for your external sound card) is connected to the AC ground at the computer power supply. The "168" you measured is the resistance (in ohms) along the convoluted path from the DC side of your laser module drivers to the computer, to the AC ground in your house wiring, and all the way back to the AC ground at the projector.

    Adam

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