The IC-92 Service Manual Index page does not mention the HM-175. There is a different publication that covers several microphones including the HM-175.
KB Number Issue 85NE1A2275 Service Manual for the HM-169, HM-170GP, HM-174, HM-175GPS HM169 HM 169 HM170GPS HM 170GPS HM174 HM 174 HM175GPS HM 175GPS
