I've a device (An old NES cart, actually) that I've fitted with a USB port and a flash drive. I'm using it in a NES to Raspberry Pi conversion. My idea was to have a port on the side for connecting to the computer to upload data (movies, ROMs, music, etc.) and use the original 72 pin connector to connect to the Pi (using the original slot loader from the NES).
Obviously 5v and Ground are soldered in parallel.
When I soldered up the USB port (basically just a USB extension cable), it works fine. However, when I add the data wires to open pins on the connector, the drive ceases to function.
I have no idea why this is happening. Any clues?