G836

This document is an Engineering Change Order (ECO) Log from Digital Equipment Corporation, detailing modifications and fixes for the G836 VR14 Regulator. It records a series of problems identified with the regulator and the corresponding corrections implemented between late 1970 and late 1973.

The documented changes address a range of issues, including:

• Performance & Stability: Problems with overload protection, voltage regulation (e.g., supply voltages being too high, oscillation at cold temperatures), general unit oscillation, thermal runaway of transistors, and distorted characters when the VR14 is used in specific systems (like the GT40).
• Component & Design Flaws: Resistors burning the etch board, undersized heat sinks and base resistors, incorrect part numbers in documentation, exposed high-voltage lines on the board, and layout issues not meeting production standards.
• Safety & Compatibility: Issues like CRT arcing damaging modules and causing phosphor burning, and ensuring proper shutdown when a fuse blows.

The corrections typically involve:

• Changing component values (resistors, capacitors).
• Adding new components (diodes, resistors for current limiting or shutdown).
• Modifying board layouts and component placement.
• Replacing problematic transistors.
• Updating documentation and schematics.

Each log entry specifies the problem, detailed correction steps, the date of the change, in-plant and field effectivity, estimated installation/test time, and associated kit contents. Several changes are noted as supplemental to or requiring conjunction with other ECOs, indicating an ongoing refinement process for the G836 VR14 Regulator.