Hi Dan,
What make and model is this deck?
Have you tried using Blackmagic Deck Control and see if you can capture? Remember to set the preferences to match your input format.
The DeckLink HD has 2 outputs and 1 input. Make sure you’re using the correct BNC connector. It should be the one furthest away from the breakout cable port.
regards
Kristian Lam
Blackmagic Design