FCO DS-173Q1-F001, Problem between Dispatcher cable & switched cable.

This document is a Field Change Order (FCO DS-173Q1-F001) released on April 9, 1990, addressing an intermittent data corruption problem in MIRA systems. The issue manifests as cross-talk between the Dispatcher and switched cables and a revision incompatibility between M7764-00 and M7763-00 modules (at Revision D or below). This leads to corrupted data during diagnostics, caused by cross-talk generated by the BC05L cable connecting the MIRA watch-dog Module (M7763-00) and the dispatcher module (M7764-00).

The FCO is applicable to all MIRA systems shipped before July 3, 1989, specifically those with Revision A1 or A2 (part numbers DS-173Q1-A2/A3) and Special Customized MIRA PDP systems using M7763 and M7764 modules at Revision D or below.

The solution involves replacing all M7763 and M7764 modules (at Revision D or below) with new Revision E modules, and replacing the BC05L dispatcher cable with a new round cable (70-27118-03). These new components feature a re-layout to adapt impedances, eliminate cross-talk, and incorporate several ECOs (e.g., M7763-AE006, M7764-AE004) and functionality enhancements.

The installation requires a complete shutdown of the MIRA system, modifying STARTUP.CMD files, and performing pre-installation MIRA tests. The FCO kit includes two M7763 modules, two M7764 modules, and two 70-27118-03 cables. The estimated Mean Time To Install (MTTI) is 13.5 hours. Post-installation, comprehensive testing using XXDP Diagnostics and MIRA under RSX is required to ensure proper functionality before reactivating the customer application. Site administration updates, including revision levels and documentation, are also necessary.