FCO 83XBX-M001, BBU may activate, causing hazardous condition

This Field Change Order (FCO 83XBX-M001) details a mandatory retrofit for all VAX 8300 systems (83XBX) Configurations 1 and 2. The primary purpose is to upgrade the H7231-L Battery Backup Unit (BBU) to Revision "C1" by installing a DEC Power Bus Cable (EQ-01469-01).

The FCO addresses a hazardous condition where the BBU may activate unexpectedly due to airflow reduction, over-temperature, or if it was initially installed without the DEC Power Bus Cable connected to the 877 power controller. This unintended activation can supply a dangerous 250 VDC potential, potentially leading to the destruction of memory arrays if cooling fails or creating a hazardous situation for service personnel.

The retrofit involves installing the specified DEC Power Bus Cable to properly connect the BBU to the power controller. Procedures for both Configuration 1 and 2 are provided, including steps for system shutdown, accessing the BBU, installing the cable, and a test to verify that the BBU is correctly disabled when the system is powered off. The estimated installation time is one hour, and approximately 600 systems are affected. This FCO incorporates ECO 7020826-LTN001.