BA11-A mounting box
The BA11-A mounting box is a 10-1/2" mounting box; the terminal variant letter notwithstanding, it is just about the last in the line of BA11 mounting boxes. It was introduced with the PDP-11/44, and was also used with the PDP-11/24 and VAX-11/730.
Maximum power was 1350W with maximum load applied; it could provide 120A of +5V, and 10A of memory refresh +5V power to MOS memory; 3A of +15V, 3A of -15V; and 5A of +12V, 1A of -12V or -15V.
The H7750 Battery Backup Unit, which provided refresh power during brief power outages to MOS memory mounted in the BA11-A, was an option.
The BA11-A does not use only the standard DEC power distribution connectors; it also provided special connections on bus bars in its power supply, and in some applications (e.g. the -11/44's KD11-Z CPU), the CPU's backplane uses unique Flexprint cables for power, which go to the special connections (see image).
For backplanes which did not have the Flexprint cables (e.g. that of the -11/24's CPU), a special 'Power Distribution Board' (DEC part number 54-13815) mounts to the bus bars and provides the needed connectors.
- BA11-A Mounting Box and Power System Technical Manual (EK-BA11A-TM-003)
- BA11-A Field Maintenance Print Set (MP00832 - May '79)
- BA11-A Field Maintenance Print Set (MP00832 - Apr '87)
- Repairing a H7140 power supply - informative blog entry on repairing an H7140 power supply
- Fan Overhaul BA11-A