Printing PDF's , elevations,  cross sections have a solid black background.  Perspective camera views also have a solid black back ground and a black grid over the picture.  I am using Apple  , X 13 and a new HP 7740 printer ( my faithful 12 year old Brother MFC6490CW is not the culprit as I thought )  Reading articles on this subject in the Forum - the cause is linked to transparent backgrounds?  using Apples' preview app?  The print shops I have sent PDF's to - not a problem - A