Australian Monitor AMIS250 - Manual (Page 5)

Muting
A VOX muting card is installed in the AMIS250. This feature provides automatic muting
of some channels when others are active. It is normally used so that a paging microphone
can have priority (by muting) over background music. VOX muting is available from
channels 1 and 2 meaning that any signal on channels 1 and 2 (mic or line) will mute
channels 3, 4, 5 & 6. The muted channels will automatically ramp back up to normal
volume when the signal on channels 1 and/or 2 is no longer active. The amplifier ships with the VOX
muting function enabled. To disable the VOX muting, disconnect the mains power lead and remove the lid
of the amplifier. Looking down from the front of the amplifier, a three position jumper (labeled JP2) is
located just to the left and behind the level pot for channel 1. To disable VOX muting, move the jumper to
the middle and left pins.
(The factory setting is with VOX enabled with the jumper on the middle and right pins).
Insert Point
The AMIS250 includes an Insert Point to allow for connection of signal processors such as equalisers,
compressors or Feedback Exterminators. The Insert Point is located (electronically) between the mixer and
power amplifier sections of the AMIS250. It allows for the “mixed” output of the AMIS250 to be
processed externally and then returned to the power amplifier section of the AMIS250.
The Insert Point is a 3 conductor (Tip, Ring, Sleeve) socket which accepts a standard stereo 6.35mm (1/4”)
jack. The one jack allows for signals to be “sent” to the processor and then “returned” to the power
amplifier. The connections are:
Tip Amplifier in. This is the return signal from the processor
Ring Mix Output. This is the signal from the mixer stage which is to be sent to the processor
Sleeve This is the ground connection
When an external processor is used via the insert point, it only affects the power amplifier section of the
AMIS250. The tape output remains unprocessed.
Fuse Sizes
Mains, 230 VAC: 6.3 Amperes Slow Blow
DC: 10 Amperes Slow Blow
Notes:
The DC fuse is located on the circuit board. This is a feature of the AMIS series amplifier,
which is equipped with a current limiting circuit preventing excessive DC current, thus
eliminating the risk of blowing high tensions fuses. In the unlikely event that the DC fuse
actuates, the output transistors should be checked, as it is probable that the amplifier has been subjected to
very extreme conditions.