A method of assembling an optical sensor assembly for a carriage of a carriage printer, the method includes providing a flexible circuit subassembly including a photosensor and a light source; providing a mounting member including a first cavity and a second cavity having an orientation that is different than an orientation of the first cavity; mounting the flexible circuit subassembly on the mounting member such that the photosensor is disposed in the first cavity and the light source is disposed in the second cavity; and affixing the mounting member to an outer housing, wherein a connector end of the flexible circuit subassembly extends outwardly from the mounting member and the outer housing