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Configuration setup
Before using the VMA-1240(B), it must be configured to match the application. Make sure the unit is
unplugged from AC mains and remove the top cover to gain access to the internal elements, then set
switches and jumpers and arrange connections as per following instruction.
J7/8/9:
These jumpers enable or disable a +12V DC phantom power supply to the microphone inputs
(25), separately for every microphone. Factory default: disabled.
J13/14/15:
These jumpers enable or disable a 100Hz high pass filter, separately for every microphone.
Factory default: disabled.
J10/11/12:
These jumpers enable transformer isolation for the Mic3 input (25). Position the 3 jumpers
all to OFF if no transformer isolation is required (factory default) or all to ON if transformer isolation is
required. Transformer isolation will decrease the sensitivity of the microphone input by 10 dB.
JP3:
Sets the source for the MOH output (x). LINE1 is default.
JP100:
Sets stereo or mono mode for the output. Factory default: stereo.
JP21/22:
Determine whether the signal at the SL stereo link preamp output (15) is affected by the emer-
gency signal or not. Factory default: enabled.
JP16/J17:
Enable a 75Hz HPF for Line Output Transformer operation. Factory default: off
Warning
The following chapter contains work on an open unit, with contacts, wires and parts
carrying life voltage exposed. Work must be expedited strictly and only when the unit is
disconnected (not only switched off) from the AC supply, and all work must be expe-
dited by a qualified technician familiar with necessary safety precautions. Removing the
top cover and expediting this work is not permitted for the end user, as indicated by the
outside marking “no user-serviceable parts inside - do not open”. Contact your dealer
to make these settings for you if you do not have the required qualification. The manu-
facturer takes no liability for damage to health or goods evolving from inobservance.
Internal jumper settings
USER MANUAL - VMA1240 INSTALLATION MIXING AMPLIFIER
Rear PCB
JP3: MOH
SOURCE
JP100:
MONO/STER.
J21/J22: LINK
J13/14/15:
MIC HPF
J10/11/12:
MIC3 ISOLATION
J7/8/9:
MIC PP +12V
J16/J17: OUTPUT HPF
