To connect to an Intercom (e.g. and Aiphone IE-JA):
-Disconnect loudspeaker from the circuit board and connect direct to the Door Interface Unit (DIU) LS connector. There does not seem to be a polarity for the speaker.
-Disconnect the Switch from the circuit board and connect direct to the BELL connector on the DIU.
-Leave microphone connected to circuit board and connect the input of the intercom (back panel of intercom) to the MIC connector of the DIU. This allows the built in audio transformer of the intercom to be used by the microphone.
-Connect the extension to Ext A, program as a hotline and test.
