I used to have a Samsung DVD/VCR combo, dv2500 or something. I was using it with a Dish receiver. (Not the Dish remote. But, I did get the receiver to control it via the 3-digit code, which is normally the same code.) I can't remember the code now. But, I do know that I found one back then.
Did you try every code for Samsung, including standalone DVD (738, 651, 652, 667, 668, 691, 740, 741) and VCR (738, 515, 517, 534, 579, 591, 675, 755), in additition to DVD/VCR (738, 667, 691)?