FCO 85XBA-1004, Trip point, signal set for VAX 85x0

This document is a Field Change Order (FCO 85XBA-1004) detailing a retrofit procedure for VAX 8500/8550 (851BA and 855BA) systems. The FCO addresses a problem where the trip point for the AC Low L Out signal, set for 226 VDC, is too high for VAX 85X0 systems.

The solution involves upgrading the H7061-A Power Supply module to Revision "B1" or higher, replacing any older revisions. This upgrade is also applicable to field spares stock. The installation procedure, estimated to take 1 hour, includes shutting down the system, ensuring ESD safety precautions, locating and replacing the H7061-A module if its revision is below B1, powering up the system, and bringing up the VMS operating system. Old modules are to be returned for upgrade. The FCO also specifies reporting the activity on a LARS form. The estimated affected population is 448 systems. The FCO was released on May 6, 1987, with parts available in March 1987.