Check the listing for details. GEM DP-40 Service Manual - Schematic Diagrams Schaltplan - Electrical Diagram DP40. Condition: Used. Listed at 14.07 USD. Schematic Diagrams (Schemi elettrici). GEM GENERALMUSIC. -Block Diagram (Schema a blocchi). SCANof original Service Manual. contents of service manual (contenuto) (8 pages - Manual sent in. ).