Field Change Order

This Field Change Order (FCO) KN220-F002 addresses problems with DECsystem 5500 units containing M7638-AA I/O modules with revision F or earlier. The identified symptoms include the system printing an incorrect revision during self-test and excessive Q-Bus activity potentially causing system hangs. The required solution is to install an M7638-AA module of revision H04 or higher. The document provides detailed rework instructions, including system shutdown, module replacement, testing, and labeling requirements, as well as an example of how to record the activity in the LARS system.