Studio Technologies 42A 2008 - Manual (Page 16)

Issue 1, February 2008 Model 42A User Guide
Page 16 Studio Technologies, Inc.
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 42A is its auto scan
feature. Pressing and holding the button
for two seconds will cause this feature to
begin operation. In this mode the monitor
source automatically “steps” through each
IFB circuit, pausing for eight seconds
before moving on to the next. Ideally, this
will allow technical personnel to observe
a problem through casual viewing of the
Model 42A’s front panel.
DC Voltage Monitoring
The Model 42A’s microcontroller integrat-
ed circuit, under software control, “watch-
es” to ensure that the DC voltage present
on pin 2 of each IFB output connector
pair is at an acceptable level. The low-
voltage threshold for the Model 42A’s
nominal 30 volt DC output is 24 volts. As
discussed in the previous section, the four
LED indicators display which IFB circuit is
currently selected for audio monitoring.
In addition, the LEDs provide an indication
of the DC voltage status on the IFB cir-
cuits. 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 interconnecting user devic-
es to active Model 42A 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 42A, the present operating
state will be stored in non-volatile memory.
Specifically, the channel selected for
audio monitoring and the status of the
auto scan function will be recorded. This
ensures that upon subsequent “power
up” the unit will return to how it was left.
If, for example, the auto scan function was
active when the Model 42A was powered
down, auto scan will begin once mains
power is again connected.
Troubleshooting
If you’re having trouble getting the Model
42A up and running, this section may
help. If you haven’t read the previous
sections of this guide, you should do so
before proceeding.