User Guide Owner's manual

Table Of Contents

z The ground line may be noisy. Use a different, “clean” grounding source. The chassis

of the MediaLink controller (if used), the power supply, the MLA VC10 Plus, and the

ampliﬁer or mixer should all share a common ground.

The audio output can still be heard when the MLA VC10 Plus has a volume setting

of 0 VDC

z Check the gain and level settings on the ampliﬁer or mixer. Adjust the gain so that you

do not hear any audio output when the MLA VC10 Plus is set for minimum volume.

z The variable voltage or resistance ports on the MLA VC10 Plus do not always reach

the absolute minimum or maximum. Therefore, if the audio ampliﬁer has remote mute

capability, use the contact closure relay switches on the MLA VC10 Plus.

NOTE: Some amplifiers do not obtain good maximum or minimum volume

control through their remote volume terminals.

The volume does not change when you change the volume setting via the MLC or

via the RS-232 commands:

z Check Power and Activity LED (a in ﬁgure 2) — it blinks green when commands

are received.

z Ensure the front panel USB connection is removed and recycle power to the 12 VDC

port only (a in the rear panel diagram on page 4).

z The wiring at the ampliﬁer or mixer terminals may be incorrect.

z Check that RS-232 settings are 9600 bps, 8 data bits, 1 stop bit, no parity.

z Check that the correct control mode (voltage or potentiometer) has been set on

the MLA VC10 Plus (see page 35). Only one port can be active at a time.

z The maximum output voltage or resistance may be set incorrectly. Retest the control

voltage of the ampliﬁer or check the user guide for the ampliﬁer to verify the

maximum voltage. Reset the maximum output voltage or resistance as required

(see page 35).

z The amplier may accept a higher control voltage than the MLA VC10 Plus provides,

so the ampliﬁer will not reach its highest volume level.

z Test the equipment with another ampliﬁer.

The volume level from the ampliﬁer changes in the opposite direction to the knob

on the controller.

z Check the wiring to ensure that the pins for resistance or voltage control are

connected appropriately (see page 6 if using resistance or page 8 if using voltage).

z Check the user guide of the ampliﬁer to see whether it should be controlled by

inverse mode. If so, use SIS commands to enable or disable inverse mode on the

MLA VC10 Plus (see page 35).

There is no voltage or resistance change or no output from the MLA VC10 Plus

control ports.

z Ensure the front panel USB connection is removed. Shut off the device and reapply

power to the 12 VDC port only (f in the rear panel diagram on page 4).

z Check that the correct control mode (voltage or potentiometer) has been set on

the MLA VC10 Plus (see page 35). Only one port can be active at a time.

If you have other problems, or for further advice, contact the Extron support staff (see

the contact information on the back page of this user guide).

MLA VC10 Plus • Operation 24