To send a byte or signal to an RS-232 to RS-485 converter using HyperTerminal, ensure the correct COM port is selected and type the desired character followed by pressing Enter. The converter should output the ASCII representation of the character sent, confirming receipt. If there is no response, verify that the converter is properly connected and powered. For troubleshooting, using an oscilloscope can help monitor the signals. Understanding the specific requirements of the RS-485 connection may also be necessary for successful communication.