Studio Technologies 40 - Manual (Page 14)

Model 40 User Guide Issue 1, July 1994
Studio Technologies, Inc. Page 15
The talent level control works just like you
would guess: turn it up for more talent
signal in the headphone mix, and turn it
down for less. The talent and cue mix level
controls work like a mixer for the head-
phone outputs, so you can have any level
you want of either source in the head-
phone mix.
Troubleshooting
If you’re having problems getting the
StudioComm system up and running, this
section can help. If you haven’t read the
other sections of this guide, you should do
so before proceeding.
Talent Amplifier Over Current LED
During normal operation the talent ampli-
fier Over Current LEDs should not light.
They will flash on and off if a talent ampli-
fier output group is loaded to exceed its
maximum output current. The most com-
mon reason for an over current condition
would be a shorted interconnecting cable.
Also, connecting more than the specified
maximum of four Model 35 or Model 38
Talent Amplifiers to each group can also
cause the LED to light. A possible, but not
likely, cause would be a fault condition
within a Model 35 or Model 38.
If an LED does flash, troubleshooting
should prove quite simple. Begin by dis-
connecting the cable that is plugged into
the applicable talent amplifier output group
connector. Perform the disconnection
directly on the Model 40’s back panel. The
LED should stop flashing. Now check
through all the wiring to determine where
the short circuit condition is located. The
Model 40 will not be damaged if the Over
Current LED is flashing so you should use
it to help you locate the fault in your sys-
tem. In just a few minutes you should be
able to isolate exactly what cable or talent
amplifier is causing the problem.
Intermittent Audio Connections
Should you experience audio connections
that seem to be “flaky” or intermittent, refer
to the Technical Notes section of this
guide. The ¼-inch 3-conductor phone
jacks used on the StudioComm products
are of very high quality, conforming to the
industry standard EIA RS-453. Some
plugs do not meet this standard, specifi-
cally in the shape of the tip conductor. In
rare cases you may have to replace plugs
on interconnecting cables or headphones
to remedy an interconnection problem.
Switchcraft No. 297 or Neutrik NP3C
phone plugs will function correctly.
Technical Notes
Talent Amplifier Cable Length
There are no hard and fast rules defining
the maximum cable length when connect-
ing Model 35 or Model 38 Talent Amplifi-
ers to the Model 40 Central Controller.
The maximum cable length is directly
related to the amount of resistance in the
connecting cable; the lower the resistance
per foot (or meter), the longer the cable
can be. (Although cable capacitance
affects high frequency performance, resis-
tance is the limiting factor is this case.)
To lay out the facts in grammar-school
story problem format: for correct opera-
tion, a Model 35 or Model 38 needs to see
at least +20Vdc between pins 1 and 2 of
their input connector. The Model 40’s
talent amplifier output voltage across pins