I am trying to control the volume from a security system microphone into a 12" TV monitor as shown on the attached schematic. The sound works OK without a volume control but it is too loud. I believe the shields should be connected together and one (+) wire connected to the center and one to the left or right terminals. This did not work. The volume did not change. Please advise, do I need some other type of volume control or what is the correct wiring for this?
First you need to determine what is the type of microphone. An electret mic is a common type but needs to be powered by the monitor. Your volume control will stop it from being powered.
The schematic JimB sent me worked. Thank you. The manufacturer (Polaris USA [sales]) said the microphone was most likely an electret type. However, it is powered by its own 12V supply and not by the monitor.
Thank you all for the help. I would have never found the answer without your assistance.