This board is designed to plug into the back of your PCjr, and allow you to connect a standard CGA monitor and a standard Serial device. It is difficult and expensive to find the original cables for the proprietary ports on the PCjr, and this board allows you to have the ports this machine should have had all along! This board has two jumpers which allow you to change the polarity of the horizontal and vertical output pins from positive to negative. Most monitors will work fine with the default settings, but the PCjr offered negative polarity on its port so we made the settings available.
Be careful when plugging this board into your PCjr. The space around the pins is fairly large on the PCjr, and it is possible to plug the connector’s top row into the bottom row of the PCjr pins if you are not careful. I had this issue myself when testing, and no damage occurred, however, the board will not work. If you have an issue getting the board to work, please look closely and ensure the board is connected properly.
One last caveat is that the pins do not quite go in all of the way. The header pins on these boards were the longest I could locate and the board tends to lean out a little. You might want to put some double sided tape on the back to secure the board if you plan to leave it in permanently.
Please see our video on YouTube if you want to see the board in action!