Studio Technologies 92 - Manual (Page 10)

Issue 1, December 2006 Model 92 User Guide
Page 10 Studio Technologies, Inc.
always take place because circuitry con-
tained within the Model 92 converts the in-
coming voltage to the required nominal 13.8
volt DC charge voltage. A minimum of 150
milliamperes is required for operation and
anything additional, up to 100 milliamperes
more, will be used by the charging circuitry.
As such, a power supply with a minimum
output of 250 mA is recommended.
A 120 volt AC input, 12 volt DC, 300 mil-
liampere, plug-in-the-wall power supply is
included with each Model 92. While good
quality, it’s a generic unit that can be eas-
ily replaced or substituted (Studio Tech-
nologies part number 10320; Digi-Key part
number MT7146). The connector required
for the power supply source is 2.1 x 5.5 mm
with positive on the inner lead. The DC input
connector on the Model 92 is a locking
type, allowing a locking mating connector
to be attached if desired.
Stand alone, the Model 92 can function
correctly as long as the battery voltage is
10 volts or greater. It will also function cor-
rectly whenever an external power source is
connected. This flexibility is due to the pres-
ence of a secondary power supply, located
on the Model 92’s printed circuit board, that
generates the 5 volts DC required for the
logic circuitry.
The Model 92’s internal battery will charge
whenever an external power source is con-
nected. The unit doesn’t have to be “pow-
ered up” for battery charging to take place.
The time required to fully recharge the bat-
tery will depend on its discharge state
at the time charging begins. Allowing 24
hours will ensure that full recharging will
always take place, although a shorter dura-
tion will probably be sufficient. The Model
92 implements a constant voltage charging
method. This minimizes the chance that bat-
tery overcharging will take place. Keeping
an external power source connected to the
Model 92 for long durations, or even perma-
nently, won’t cause damage to the battery.
Note that a text message will be displayed
whenever the Model 92 is operating under
battery power and an external power source
is then connected. To indicate that the exter-
nal source has been detected, the LED dis-
plays will briefly show the message CHRG.
Removing an external power source will not
result in any message being displayed.
System Modes
The Model 92 can be set to one of four
overall ways of operating. These are called
the system modes and the choices are
local, master-male active, master-female
active, and slave. Refer to Figure 3 for de-
tails The local system mode is intended for
testing DT12 cable assemblies where both
ends will be connected to the same Model
92. This is the default system mode and the
one that will most commonly be used. The
other three system modes are provided so
that two Model 92 units can work together
in a master-slave arrangement. This unique
capability allows testing of cable assemblies
that are permanently installed or already
deployed in a facility or venue. Specifically
this is the situation where the connectors on
both ends of a single DT12 cable assembly
are not accessible for connection to the
same Model 92.
To select the desired system mode, press
and hold the power button. The four
modes will “cycle” through. Release the
power button when the appropriate indi-
cator light is active. The selected system
mode will generally remain in effect until
it is manually changed. Power cycling the