Manual Library / Denon. Denon HiFi Components. Product Catalogue. add a review. Content. 1975; DRM-500, DRM-700, DRM-800, DRW-750, PMA-1520, PMA-250, PMA-320, PMA-520, PMA-720, PMA-920, POA-2400A, POA-4400A, POA-6600A, PRA-1200, SC-200, SC-300, SC-500, TU-450, TU-450L, TU-460, TU-460L, TU-550, TU-550L, TU-600, TU-600L, TU-800, TU-800L The first thing to be done is to proof out the RS-232C cable to make sure it has been terminated properly to the correct pins on both ends and that there is continuity on all wire leads. If this proofs out good, then in place of running a new full pin to pin DB-9 cable, try a chassis ground wire connection from the chassis of the Denon Get in touch with one of our specialized Denon product representatives. Email Us. Get in Touch. Call Us . Denon General Customer Service Phone: 800-497-8921 Denon Online Order Support Phone: 855-720-0823. Customer Service Hours. Monday to Friday: 10 AM to 7 PM All hours are Eastern Standard Time Home Theatre. AV Receivers; Sound Bars;