The IN501, HDMI Input Board Assembly is a Series 500 input board compatible with all Series 500 enclosures, such as the PS550. This board is used to connect audio-visual source devices using the HDMI version 1.3 or earlier standard. Installation is quick and painless. UNPLUG THE POWER CORD ATTACHED TO THE ENCLOSURE. Simply remove the single mounting screw that holds the IN500 Future Expansion Plate or other card where you plan to install the IN501. After removing the old plate, insert the new IN501 assembly. Replace the screw and reattach the power cord. The system automatically recognizes the new board installed so no further activity is required. However, in some cases, it may be necessary to adjust the audio trim to level the input amplitude to a nominal level. See the Installation Manual for more details regarding audio adjustments.