Service Manuals, User Guides, Schematic Diagrams or docs for : Samsung Monitor Samsung_D490_D450_Training_PN43D450_PN51D450_PN43D490_PN51D490_PL43D450_PL51D450_PL43D490_PL51D490_PS43D450_PS51D450_PS43D490_PS51D490_[TM]
Most service manuals and schematics are PDF files, so You will need Adobre Acrobat Reader to view : Acrobat Download
Some of the files are DjVu format. Readers and resources available here : DjVu Resources
For the compressed files, most common are zip and rar. Please, extract files with Your favorite compression software ( WinZip, WinRAR ... ) before viewing.
If a document has multiple parts, You should download all, before extracting.
Good luck. Repair on Your own risk. Make sure You know what You are doing.