EVAL-ADV7842-7511 Questions (Laserdiscs!)

Hi,

I'm using the EVAL-ADV7842-7511 primarily for its excellent 3D comb filter as part of a non-profit Laserdisc archival project.

I have a few questions.

  1. Do I need to execute a power down sequence or can I just pull the plug? If I just pull the plug, then will I harm the board in any way? I've been pulling the plug so far and it has been working fine, but I don't want to do long-term damage to the board.
  2. I noticed while mounting the board on standoffs that it had a bit of bow/twist. I had to bend the bottom-left standoff a bit in order to get the screw in. Is this OK? Does bow/twist have any impact on the long-term health of the board?
  3. Which registers do I need to modify in order to re-position the captured image within the output frame? I verified that the Video Essentials laserdisc has more than this in its active picture area with another A->D device. It seems like the current values have the image cropped a bit and placed in the upper right of the 720x486 frame.eyRabWU.png
  4. Does the dering function correct gibbs phenomenon (ringing/ghosting) artifacts? I can't get it to do much for my Pioneer LD-V8000 laserdisc player, even at the maximum setting. This is not a capture from my unit, but it's a pretty good representation of what it looks like (hint: look to the right of sharp edge transitions):xLR1vNz.png
  5. Just making sure: The ADV7511 only does deep color for 4:4:4, right?

Thanks!

  • 0
    •  Analog Employees 
    on Oct 28, 2015 6:23 PM over 4 years ago

    1) We just pull the plug all the time without seeing any problems

    2) The board should not have any bow in it.  There are fabrication specifications which limit non-linearity.  Not exactly sure what the problem is with the board.  In general repeated flexing of boards can break solder joints over time.

    3) Check out the ADV7842 hardware manual section 10.9.1 CP Primary Synchronization Signals.  Normally the default scripts should work fine.

    4) Ghosting might be caused by poor impedance matching between the laser disc and the ADV7842 over the cable in the analog domain.  The filters within the device do not cause ghosting.  There might be some edge artifacts depending on how the filters are configured.

    5) Yes, the ADV7511 will do Deep Color 444

  • 4) Ghosting might be caused by poor impedance matching between the laser disc and the ADV7842 over the cable in the analog domain.  The filters within the device do not cause ghosting.  There might be some edge artifacts depending on how the filters are configured.

    What's the impedance rating of the CVBS input on the board? I imagine 75-ohm, but I also know that RCA connections aren't capable of 75-ohm. Is there some kind of outboard impedance matching device I can use?

    The composite video cable I'm using is made by Blue Jeans Cable. It's a 3ft. Belden 1694A with Canare RCAP connectors which, I'm told, is as close as RCA gets to 75-ohm. Composite Video Cables at Blue Jeans Cable

    In general repeated flexing of boards can break solder joints over time.

    By "repeated" do you mean bow-unbow-bow-unbow? Is it fine if it's just once and then left as-is?

    Thanks for your help with this so far!

  • 0
    •  Analog Employees 
    on Oct 29, 2015 12:46 AM over 4 years ago

    The board was designed as a 50 Ohm board.  The 24 -51 Ohm divider resistors are place right next to the incoming connector converting the 75 Ohm cable to 50 ohms so they can run on the board.  The RCA connectors and cables should be 75 Ohm. 

    Yes, repeated flexing can cause solder failure, doing it just once should be fine, like when you bolt it to another platform.