Studio Technologies 41 2007 - Manual (Page 15)

Model 41 User Guide Issue 2, February 2007
Studio Technologies, Inc. Page 15
The front-panel-located pushbutton switch
serves two purposes: selecting the source
to be monitored and enabling the auto
scan feature. To manually select an IFB
circuit to be monitored, press and release
the button until the status LED associated
with the desired IFB circuit lights. Each
press of the button will advance the circuit
number to be monitored by one. A delay
is built into the circuit selection process
allowing a user to move from, for example,
circuit 1 to circuit 3. Simply by pressing
the button twice in rapid succession circuit
2 will be automatically skipped.
Unique to the Model 41 is its auto scan
feature. Pressing and holding the button
for two seconds will cause this feature to
begin operation. In this mode the moni-
tor source automatically “steps” through
each IFB circuit, pausing for 8 seconds
before moving on to the next. Ideally, this
will allow technical personnel to observe
a problem through casual viewing of the
Model 41’s front panel.
DC Voltage Monitoring
The Model 41’s microcontroller integrated
circuit, under software control, “watches”
to ensure that the DC voltage present
on pin 2 of each IFB output connector is
at an acceptable level. The low-voltage
threshold for the Model 41’s nominal 30
volt DC output is 24 volts. As discussed in
the previous section, the four LED indica-
tors display which IFB channel is currently
selected for audio monitoring. In addition,
the LEDs provide an indication of the DC
voltage status on the IFB circuits. An LED
will “flash” at a moderate cadence if the
voltage on its associated IFB circuit falls
below the acceptable value. This can be
caused by a temporary over-current or
short-circuit condition, such as when inter-
connecting user devices to active Model
41 IFB circuits using portable cabling.
An under-voltage condition that’s pres-
ent for a continuous 4-second period will
cause a fault condition to be recognized.
The status LED associated with the prob-
lem IFB circuit will indicate this condition
by flashing at a faster rate. In addition,
the output voltage on that specific IFB
circuit will automatically shut down to an
essentially off condition. A 10-second
“cool down” period will then take place,
after which the output voltage will again
become active. As soon as the output is
enabled normal output voltage monitor-
ing will again take place. A continuous
short-circuit presented to an IFB output
will result in a continuous 4-second on,
10-second off error cycle. It’s important to
note that during the 10-second off period
no voltage monitoring takes places. Re-
moving the fault condition will not result
in the output voltage immediately turning
on again; the 10-second shut down period
must first elapse.
Operating Parameters
As expected with professional equipment,
whenever mains power is disconnected
from the Model 41, the present operating
Figure 8. Detail of front panel showing
headphone section