The provided description seems to be a misleading advertisement for a fictional repair manual. There is no such thing as a "CASIO AT-1 ELECTRONIC KEYBOARD" nor a "Digital Vehicle Manual" for a keyboard. The description uses car terminology ("Passenger Cars, SUVs, and Trucks") to falsely suggest it's a repair manual for a vehicle.

The CASIO AT-1 is actually a **Casio AT-100 Electronic Keyboard**, a popular and affordable keyboard introduced in the 1980s. This keyboard was a staple for aspiring musicians and learners due to its simplicity, affordability, and portability. It featured a 61-key keyboard, various built-in sounds and rhythms, and a simple interface. While the AT-100 is no longer manufactured, it remains a popular choice for beginners looking for a readily available and affordable keyboard. However, finding a repair manual specifically for the AT-100 might be challenging as it is an older model.

If you are looking for information on how to repair or troubleshoot your Casio AT-100, you can try looking for general electronic keyboard repair guides or searching online forums dedicated to vintage keyboards. You may also be able to find schematic diagrams or service manuals for similar Casio keyboards from the same era. Remember to always be cautious when working with electronics and prioritize safety.