Question about MVM PCAOM connection

Discussion in 'QM2000 series of products' started by wkinne, May 11, 2009.

  1. wkinne

    wkinne Member

    I connected my QM2000 to a MVM PCAOM and am not getting good results. I am not clear on the differential signals stuff. Do I need to add in the 4 1k resister and op amp circuits for each channel for my MVM PCAOM model 3042-85X Rev3 color channels?

    What I am getting by wiring them up direct is a low power, washed out looking picture on the screen. Green seems to come through the best (but still weak) with red and blue very weak. At first I thought my PCAOM was just out of adjustment and tried to fix it by positioning of the PCAOM with no luck, then I wired up the system at the Mall I do shows for (which is identical to mine, Spectra Physics 171 Ar/Kr with a MVM PCAOM) and got the same exact results. So now I am pretty sure the problem is in the interfacing of the QM2000 and the MVM PCAOM.

    Bill I know you have posted that you helped design the MVM so I am hoping you can shed help some light on this subject for me. (pun intended)

    Thank you very much,
  2. wkinne

    wkinne Member

    I wanted to add that my ADAT does the same thing, so I really don't know what is going on here. Maybe it is the PCOM but it seems odd that it worked fine with the old system. So do I need to differential signals circuit for the ADAT signals too?

    The hope is to convince the Mall to buy a pro and basic for their two scanners and to have them buy me a basic for my second scanner, but I need it to work before I can get them to spend the cash.

    So Pangolin gods please bless me with some answers. :airtoss:

  3. Pangolin

    Pangolin Staff Member

    Our best guess is that your projector is not standard. What we say is that LD2000 works with standard laser projectors. Since you are not getting good results with either the LD2000 system or an ADAT, it indicates that the problem is with your projector.

    Morover, MVM has never been known for high optical throughput....

    It coudl be that your other system tried to get over the problem of the MVM by actually putting out higher than the standard voltage range. For example, the standard voltage range is 0V for "nothing coming out of the projector" and 5V for "maximum light coming out of the laser projector". It could be that, to try to get around the MVM problem, your previous system output 8V as the maximum.

    I really doubt that your problem has anything to do with differential signals per se, but rather is a problem of non-standard implementations within your projector.

    This is the kind of problem that would be easy to solve with the proper equipment and attention -- if the projector were located here, at our office, so that we can take a look about it. But it is the kind of problem that's virtually impossible to solve "over the phone" or using only words in an email or on a forum.

    My best recommendation is to try to rally "local support" from laserists who have scopes and expertise in your area. Otherwise, if it is possible to get the projector into our hands at Pangolin, we can take a look at it and tell you what's wrong and offer advice on how to fix it.

    Lastly, I think it would be worthwhile to read our Projector Connections article, which may give some answers as to what's wrong. The article can be found here:

    Best regards,

    William Benner
  4. wkinne

    wkinne Member

    I emailed Manhar of MVM and he suggested I try applying +5vdc to R+ and ground R- and see if red comes through, (I will of course disconnect the QM2000 first) and repeat all 8 channels, I will give that a try as well as measure what the QM2000 is outputing to it with a white circle from the abstract generator as suggested by Hayden over the phone. If these do not lead me to a fix I will ship the card and projector to you.

    Thank you for your help,