Extron Electronics MLA-VC10 - Manual (Page 26)

MLA-VC10 • Installation and Setup
Installation and Setup, cont’d
2-14
Wiring TOA 900 Series amplifiers
At high volumes, when the MLA-VC10 is used to control
TOA 900 series amplifers unwanted "ticking" and low "hum"
may be heard at the speakers of a projector or monitor. This
is caused by a lack of proper ground isolation between the
MLA-VC10 and the TOA amplifier, which creates ground
loops between the products. To remove this unwanted noise,
follow these steps and see figure 2-14:
1. Configure the DIP switch setting on the
MLA-VC10 for a control voltage of 0.24 V
(see the figure at right and page 3-11).
2. Connect a 1k ohm resistor between the
Ground ( ) terminal of the MLA-VC10 and
the lower terminal of the TOA 900 Series Remote Volume
terminals. It is recommended that the resistor is placed
closest to the amplifier
N 22 AWG wire is recommended for connecting the resistor
between the MLA-VC10 and the TOA 900 Series
amplifier.
3. Connect the "CTL" terminal of the MLA-VC10 Amp/Mixer
Control port to the upper terminal of the TOA 900 Series
Remote Volume terminals.
4. Ground the chassis of the MLC to the display. Either run
a ground wire from the chassis screw of the display to any
ground pin on the MLC or, if using an Extron Serial cable for
projector control with a DB9 connector, attach the shield wire
of the cable to any ground pin on the MLC.
5. Ground the chassis of the MLC to the TOA amplifier. This can
be done by running a wire from the chassis screw of the TOA
amplifier to any ground pin on the MLC.
6. Use Global Configurator 2 software to configure the
MLA-VC10 driver appropriately (see pages 3-2 to 3-10).
3 4 1 2 7 8 5 6
ON
DIP Switches
set for 0.24 VDC