I use a Radio Shack replacement AC adapter on my BVP4+
The original one was in bad shape when I got it.
Just for you, I crawled behind the rack, removed the adapter, and took a photo!
BVP4-plug.jpg
You need a 12V 500mA AC adapter (USA NTSC 120V 60Hz)
Radio Shack part # 273-1773
Take the BVP4+ with you, to make sure you get the correct plug head, the piece that goes into the unit. It should fit without being too tight or too loose. The blue-tipped one is perfect, although the colors may be different (I believe the last one I bought for a BVP4+ had a yellow head).