Manual

Issue 3, November 2013 Model 41 User Guide
Page 16 Studio Technologies, Inc.
Troubleshooting
If you’re having trouble getting the Model
41 up and running, this section may help.
If you haven’t read the previous sections
of this guide, you should do so before
proceeding.
If the Model 41 Doesn’t
Function At All
A source of AC mains power must be
connected to the Model 41. The unit is a
“universal input” type so that applying pow-
er in the range of 100 to 240 volts, 50/60 Hz
is acceptable. Whenever AC mains power
is connected the front-panel LEDs should
go through their power-up routine, light-
ing in a processor-controlled sequence. If
this does not occur confirm that AC mains
power is active (“hot”) and that the cord is
securely mated with the inlet connector on
the Model 41’s back panel.
In all foreseeable situations, both normal
and abnormal, the status and meter LEDs
should go through their normal power-up
routine. However, it’s possible that if all
four IFB outputs are being presented
with a short-circuit condition, the internal
36 volt power supply may enter its protec-
tion mode and shut down. In this case no
LEDs will light. If this scenario occurs, even
after confirming that AC mains power is
correctly being applied, try removing the
loads from the IFB outputs. The easiest
way to do this is to remove the 3-pin female
XLR connectors that are plugged into the
Model 41’s back panel. If normal operation
then begins, carefully check the IFB output
wiring for fault conditions.
If the front-panel LEDs still don’t go through
their power-up routine, even after confirm-
ing that AC mains power is present and that
the IFB outputs are not shorted, it’s likely
that the unit requires factory service. F
or
safety in the event of a major internal failure,
the internal 36 volt power supply contains a
fuse in series with the incoming AC mains
power. This fuse will open (“blow”) only if
a serious failure occurs inside the unit. The
fuse is not field-replaceable. The Model 41
must be returned to the factory or an autho-
rized service location for review and repair.
Maintaining Correct Input
Signal Levels
The Model 41’s four 2-channel audio inputs
are designed for nominal signal levels of
+4 dBu. Applying signal levels significantly
lower than +4 dBu will reduce the signal-
to-noise ratio (raising the perceived noise
floor) and can prevent the connected user
devices from operating optimally. Applying
signal levels significantly higher than
+4 dBu will reduce the headroom and
greatly increase the chance of reaching
audio “clipping.” Obviously, these cautions
are not unique to the Model 41, but apply
to most audio equipment. The front-panel
level meters provide an easy means of con-
firming that the Model 41 is being presented
with the correct audio levels.
To confirm correct IFB output operation at
locations away from where the Model 41 is
installed, it’s possible to use the Model 72
Level Meter/Interface, also available from
Studio Technologies. The Model 72 is a
compact, portable device that plugs directly
into IFB or intercom circuits and provides
two useful functions. Two 5-segment LED
meters display the audio levels present on
pins 2 and 3 of the connected circuit. In
addition, two “dry” line-level audio outputs
are provided. Complete information on
the Model 72 is available on the Studio
Technologies website.