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BMX SERIES III CONSOLE
NOTE: An important feature when troubleshooting the BMX III is that modules may be removed or
inserted with power supplied to the console.
To remove a module from the mainframe, remove the black button head retaining screws from the top
and bottom of the module, and the silver button head screws from the module face. Screw the Module
Pull/Extractor Tools (PR&E #70-43) into the holes vacated by the silver button head screws, and then
use both hands to extract the module from the mainframe.
Once the module at fault has been identified, it is recommended that the Equipment Description section
for the module in question be read thoroughly prior to troubleshooting that module. Use the appropriate
module extender board (PR&E #99-272 for input, Slate/Talkback/Test Oscillator and Send And Return
Modules; PR&E #99-274 for Control room and Studio Monitor Modules; PR&E #99-231 for Monaural
Output, Telco Mix and Meter Switcher Modules; PR&E #99-230 for Processing Modules; and PR&E
#99-273 for Stereo Line Output Amplifiers) or standard bench service techniques to isolate the problem.
NOTE: Most of the analog and logic components are socketed for ease of replacement.
WARNING: The CMOS logic devices are susceptible to destruction from static discharge while being
handled. It is recommended that considerable caution be exercised when working with these parts.
6.3 LEVEL ALIGNMENT
All consoles are set for a +4 dBu output level unless +8 dBu is specifically requested at the time of order.
It is very important that the test levels are maintained exactly as specified to avoid a buildup of tolerance
errors. The GAIN TRIM controls on the output amplifiers should not require trimming unless
components which affect amplifier gain have been replaced.
Input module GAIN TRIM controls should always be adjusted so that the input accommodates the
signal level of the source equipment.
BMX III modules were aligned at the time of factory test in accordance with the following procedures
(NOTE: Instructions for aligning the console for an output level of +8 dBu are contained in Section
5.2):
MICROPHONE INPUT MODULES
Apply a 1 kHz test signal at -50 dBu (150 ohm source) to the module input. Adjust the module GAIN
TRIM controls for a -10 dBu output at the module Patch Send.
STEREO LINE INPUT MODULES
Apply a 1 kHz test signal at +4 dBu (600 ohm source) to both the left and right module inputs. Adjust
the module GAIN TRIM controls for a -10 dBu output at the module Patch Sends.
PACIFIC RESEARCH & ENGINEERING
REVISION C
100
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