VT101 Hot Line Troubleshooting Card

This document serves as a hot line troubleshooting guide for VT101, VT102, and VT131 series video terminals, supplementing the VT101 Series Pocket Service Guide. It details procedures for configuring various SET-UP features, including parity, modem, and printer settings, often requiring the use of the SHIFT key in combination with other keys.

The guide provides extensive "Set-Up B" diagrams for VT101 and VT102/VT131 models, illustrating the available configuration options for display, communication, and terminal behavior. A "Set-Up C" diagram is also included specifically for the VT131, detailing advanced edit and protection features.

A significant portion of the document focuses on troubleshooting common hardware malfunctions, starting with self-test error codes for VT101 and VT102/VT131 models, indicating potential issues with the Terminal Controller Board or Keyboard. Comprehensive troubleshooting steps are provided for power-related problems, such as:

• Terminal not plugged in or no power at the wall socket.
• Internal short or open in the power cord.
• Blown fuse.
• Lack of AC voltage to the power supply or secondary voltage from the transformer.
• Incorrect or absent DC voltage to the controller board.

Further troubleshooting covers checks for the Keyboard, Terminal Controller Board, and Video Monitor Board voltages, along with issues related to the Flyback Assembly, CRT Cable, and incorrect power-up responses (e.g., cursor not appearing, random LEDs flashing, random characters, or an inoperable terminal despite a visible cursor).

The document also includes instructions for board configurations, specifically on how to install substitute main character ROMs and considerations when replacing VT101, VT102, and VT131 controller boards. Detailed physical functional diagrams provide pinouts and expected voltage readings for the Video Monitor Board, Power Supply Board, Terminal Controller Board, Keyboard, and 20 mA Board, crucial for advanced diagnostics. Exploded diagrams of the terminal and a block diagram illustrate the physical layout and interconnections of the system's components.