Equipment Description; Mainframe; Function; Circuitry - Pacific Research BMX-III-18 Operation And Technical Manual

BMX SERIES III CONSOLE

4.0 EQUIPMENT DESCRIPTION

This chapter describes the functions and circuitry of the various components incorporated in the BMX
III console and its associated modules. Included are sections describing the mainframe, Microphone
Input Module, Stereo Line Input Module, Stereo Line Output Amplifier, Control Room Monitor
Module, Two-Studio Monitor Module, Monaural Line Output Amplifier, Monaural Output/Telco Mix
Module, Send and Return Module, Monaural Output/Telco Mix/Send And Return Module, Slate/
Talkback/Test Oscillator Module, Meter Switcher Module, Remote Line Selector Module, VU Meter
Power Regulator, VU Meter Buffer Amplifier, and Power Supply Assembly.
Corresponding diagrams and schematics are located in Chapter 7.

4.1 MAINFRAME

4.1.1 Function

The console mainframe contains all the interconnection wiring required to accommodate a full
complement of modules. Each input position is wired in a universal fashion and, therefore, will accept
either a Microphone Input or Stereo Line Input Module.
NOTE: Section 7.27 has the complete mainframe wiring diagrams.

4.1.2 Circuitry

The only active electronic components in the mainframe are the VU meter power regulator assembly
and the meter buffer amplifiers. These are described in detail in Sections 4.14 and 4.15, respectively.
The meter buffer amplifiers are mounted on their respective meters, and the power regulator assembly
is mounted on the bottom of the console mainframe, beneath the Remote Line Selectors. The VU meter
distribution board is mounted inside the mainframe, immediately below the meters.
NOTE: The BMX III power supply assembly provides ±22 volt DC power to the console mainframe.
This is regulated to ±16 volts DC by the VU meter regulator assembly and by regulator assemblies on
all BMX III modules except output amplifiers, which regulate the ±22 volt DC power to ±18 volts DC
(reference the module schematics located in Chapter 7).
The meter panel assemblies on the BMX III-10 and BMX III-14 are equipped with two sets of stereo
VU meters (PROGRAM and AUXILIARY). The Audition and Utility buses are metered on the
Auxiliary meters, as selected by the Meter Switcher module.
The BMX III-18 and BMX III-22 are equipped with three sets of stereo meters (PROGRAM,
AUDITION and AUXILIARY). The Utility bus is metered on the Auxiliary meters, as selected by the
Meter Switcher module.
The BMX III-26, BMX III-30 and BMX III-34 are equipped with four sets of stereo meters
(PROGRAM, AUDITION, UTILITY and AUXILIARY).
PACIFIC RESEARCH & ENGINEERING REVISION C
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