A service manual is different from a user manual. While a user manual tells you how to change channels, a service manual is for repairs and contains:
Hidden remote control codes used to access the "Factory Menu" for calibrating colors or resetting the firmware. Sansui Lcd Tv Service Manual
Since Sansui's official support has shifted over time, these reputable third-party databases are the best places to look for PDF service manuals: A service manual is different from a user manual
Diagrams showing how the plastic casing and internal components fit together. Sansui Lcd Tv Service Manual