BA11-L Mounting Box Technical Manual

This technical manual, published by Digital Equipment Corporation (DEC) in October 1977, describes the BA11-L mounting box, a key component for PDP-11/04, PDP-11/34, or PDP-11/34A systems, and as an expander box for peripheral controls.

The document provides comprehensive information across several areas:

1. Characteristics and Specifications: Details the physical attributes of the BA11-L, including its chassis size, weight, mounting capacity for backplanes (double or single system units), and environmental specifications. It introduces the main power supply (H777) and an optional battery backup unit (H775A), along with a remote power control system.
2. Backplane Configurations and Installation: Explains the different types of backplanes (DD11-PK, DD11-DK, DD11-CK) that can be housed in the BA11-L, their physical layouts, and electrical pin designations (Standard Unibus, Modified Unibus, Small Peripheral Control). It details power harness connections and general installation requirements.
3. H777 Power Supply: Provides an in-depth technical description of the H777 multivoltage power supply. This includes functional block diagrams, detailed circuit analyses of its major assemblies (AC Control, MOS Regulator, Core Regulator, +5V Regulator), and sub-circuits like the Raw DC, Master Clock, Power Sequence Control, Battery Monitor, and Boot Enable circuits. It specifies the power outputs (e.g., +5V, ±15V, +20V, -5V) and their functions for different system components.
4. H775A Battery Backup Unit: Details the optional H775A, explaining how it provides battery input voltage to the MOS regulator during AC power failures to maintain MOS memory refresh. It covers its physical description, functional operation, and circuit descriptions for its voltage boost, regulator, charge rate, and battery discharge limit circuits.
5. Maintenance: Outlines preventive and corrective maintenance procedures for the BA11-L mounting box, the H777 power supply, and the H775A battery backup unit. This includes troubleshooting flowcharts, voltage checkpoints, fuse checks, and instructions for component removal and replacement.

In essence, the manual serves as a complete technical guide for understanding, installing, and maintaining the DEC BA11-L mounting box and its critical power and interconnection components.