RK11-C Disk Control Engineering Change Order Log

This document contains a series of Engineering Change Orders (ECOs) for the RK11-C Disk Control system, recorded between February 1972 and June 1973. It details various problems identified, including circuit schematic omissions, head alignment procedures, cabinet assembly errors, and power wiring discrepancies. For each issue, the document specifies the corrective action taken, such as updating assembly parts lists, modifying drawings, or adding components like fans and power controls. It also includes specific technical instructions for retrofitting the RK11-C to address a fatal drive error (DRE) condition, noting in-plant and field implementation timelines.