FCO 82XBX-M001

This document is a Field Change Order (FCO 82XBX-M001) dated April 17, 1987, for all VAX 8200 (82XBX) systems, Configurations 1 and 2. Its primary purpose is to address a hazardous condition by upgrading the H7231-L Battery Backup Unit (BBU) to Revision "C1."

The problem arises when the H7231 BBU is installed without the DEC Power Bus cable connected to the 877 power controller. In such cases, an airflow reduction or over-temperature condition can cause the BBU to activate, supplying a dangerous 250 VDC potential. This can lead to the destruction of memory arrays due to overheating if cooling fails, or create a severe electrical hazard for service personnel if system power is cycled off while the BBU remains enabled.

The solution involves retrofitting affected systems by installing the new DEC Power Bus Cable (Part Number EQ-01469-01) between the H7231 BBU and the 877 Power Controller. The estimated installation time for this procedure is 1 hour. Detailed step-by-step procedures are provided for both Configuration 1 and 2, which include shutting down the system, physically installing the cable, and performing a test to verify that the BBU correctly disables when the main power is off. Field spares stock of the H7231-L BBU must also be upgraded. Approximately 600 systems are affected by this FCO.