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Highlights
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Tests DT12 cables and fanouts
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Channel or pin mode testing
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Complete test in less than six seconds
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End-to-end testing supported
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Simple error codes display fault conditions
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Circuitry protected from outside voltages
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Rugged LED-based displays
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Internal rechargeable battery
Overview
The Model 92 is designed
to test the integrity of DT12-type cable assemblies. Widely used by the
mobile broadcast industry, “DT12s” provide twelve balanced signal pairs,
each with an individual shield. For on-air broadcast applications it’s
critical that all signal paths are fully functional. But without
specialized test equipment it’s impossible to confirm DT12 performance.
The Model 92 accomplishes this task in a simple-to-use but technically
sophisticated manner—it’s far from just a continuity checker. Under
software control, the internal microcontroller-based circuitry
independently tests each signal pin for connectivity, opens, and shorts.
The Model 92 can ensure that the value of a television production
trailer’s significant investment in DT12 cable assemblies is maximized.
When two Model 92 units are used together they can prove invaluable for
facilities that include permanently installed DT12 cabling.
For operator convenience, testing can be selected from among two
formats: channel mode or pin mode. Channel mode is provided specifically
for field applications where testing is most effective when oriented
toward how a DT12 is actually used. Pin mode is oriented toward
supporting technical personnel who are responsible for fabricating or
repairing cable assemblies. In both modes solid-state displays indicate
which channel or pin is being tested, along with the test result. For
ease of use the Model 92 supports both automatic and manual testing. The
unit is housed in a rugged aluminum enclosure and is constructed for
reliable “field” performance where abuse is often a way of life. An
internal rechargeable battery provides the operating power.
When the Model 92’s channel mode is selected, testing is organized as
twelve signal channels. Two of the display digits indicate which channel
is currently being tested. The display digits, depending on which mode
is selected, can also display the test results. The results can include
“all ok” and “fail,” as well as a number of error codes. The codes allow
conditions such as open shields or pins, crossed signal pairs, or short
circuits to be displayed. In the pin test mode, all 37 pins associated
with the FK37-type connectors can be independently tested. Two of the
display digits indicate which specific pin is being tested. The other
two digits can display which pin (or pins) are connected to the pin
under test.
The Model 92 is capable of testing individual cable assemblies where
both the male and female 37-pin connectors associated with a specific
DT12 are accessible. Referred to as the Model 92’s local system mode,
both connectors of the designated cable assembly are terminated on the
Model 92. This mode is appropriate for testing flexible cable assemblies
that are newly assembled or are being prepared for temporary deployment.
With rapid and complete testing, DT12s will either be confirmed as ready
for use or “flagged” for repair or replacement.
The Model 92 allows testing of DT12 “fanouts.” These cable assemblies
typically have a female or male 37-pin connector on one end and twelve
male or female 3-pin XLR-type connectors on the other. Connecting this
type of fanout to the Model 92 is simple. In addition to male and female
37-pin connectors, the Model 92 also provides two 3-pin XLR-type
connectors, one male and one female. Under software control, a
technician can “walk through” the twelve channels, connecting one fanout
channel at a time. In addition to testing fanouts, this feature can find
use in testing DT-type cabling that terminates on patch bays or breakout
panels. As a “bonus” the Model 92 also supports testing of standard
3-conductor audio cables that terminate on XLR-type connectors.
A unique testing challenge is encountered when DT12 cable assemblies
have already been “run” in preparation for a broadcast event or have
been permanently installed as part of a facility’s infrastructure. Using
the master/slave system modes, two Model 92 units can work together to
perform end-to-end testing of in-place cabling. This unique capability
can be valuable for new
installations as well as during routine maintenance and repair. Using a
separate cable path, a bidirectional data link is established to allow
the two Model 92 units to coordinate their resources. One unit is
designated as the master while the other is designated as the slave. Two
master modes ensure that DT12 cable assemblies with either male or
female connectors on the master end can be tested. While the buttons on
the master unit control the testing functions to be performed, both
units simultaneously display the test status. A BNC connector is used to
establish the data link between the two Model 92 units. This connector
type was selected because of its common use in broadcast
applications. However, cable other than 75 ohm coax can also be used for
the data link, including microphone, “CAT5” data, and multi-pair “telco.”
Four pushbutton switches, five LED indicators, and a 4-digit LED display
provide the Model 92’s operator interface. The power button is used to
power up and power down the unit. The power button is also used to
select which of the four system modes is selected. Four LED indicators,
one associated with each system mode, display which mode is active. The
up and down buttons allow manual selection of the channel or pins
designated for testing. The up button is also used to select which cable
mode is active. The down button is also used to select between channel
and pin mode. The auto test button is used to enable the two automatic
test sequences. The LED display indicates which of the twelve DT12
channels or 37 individual connector pins is currently being tested. And,
depending on which test is selected, will also display the test results
in a variety of ways. These green-colored LED displays were selected for
their visibility and long-term reliability. An LED indicator is also
provided to confirm when data associated with the master/slave mode’s
data link is present.
The Model 92 provides two automatic test sequences: auto test and
continuous auto test. The auto test sequence is the unit’s fastest test
method, specifically included to support busy field broadcast
applications. It takes less than six seconds from the time the auto test
pushbutton is pressed until the test results are displayed. In the
channel mode, auto testing begins with channel 1 and continues on
through to channel 12. When selected for pin mode auto testing will
begin with pin 1 and continue on through pin 36. (While available for
manual testing, pin 37 is not part of the auto test sequences.) During
the auto test sequence the LED display will indicate which channel or
pin is being tested. At the end of the entire test sequence one of three
result messages will then display: all ok, fail, or open. As expected,
when the result is all ok the DT12 is ready for use. A fail message will
display if one or more errors are detected. And open will display should
no pins be detected as being connected. This typically indicates that
the cable designated for testing has not been correctly connected to the
Model 92.
The continuous auto test sequence is enabled whenever the auto test
button is pressed and held. Using this test sequence, the Model 92 will
test all channels or pins followed by a summary results message.
However, the difference with this test sequence is that the results for
each individual channel or pin will be displayed as testing progresses.
Whenever a defective channel or pin is detected the sequence will pause
momentarily while the right two digits display the applicable error
information. The test sequence will then continue on to the next channel
or pin. After a slight pause for the summary results to be displayed,
testing will continue, again starting with channel 1 or pin 1. The
continuous auto test mode was specifically included for situations where
a more detailed view of the test results is desired.
To ensure a thorough analysis of the connection status of a DT12 cable
assembly the Model 92 is capable of testing all 37 pins
of the male and female mating connectors. This allows confirmation of
correct channel wiring, as well as detecting opens, shorts, and reverses
(pair crosses). All Model 92 input and output circuits are extensively
protected from damage due to static discharge (ESD) and DC voltages
commonly found in broadcast environments. These voltage sources can
include tally, intercom, IFB, and microphone phantom power among others
that might be present on a DT12 cable assembly that has been designated
for testing.
Contained within the Model 92’s enclosure is a rechargeable 12 volt
sealed lead-acid battery. This will provide continuous operation in
excess of eight hours before recharging is required. An external 12 volt
DC power adapter, provided with each Model 92, allows simultaneous
charging of the battery and powering of the unit. Circuitry contained
within the Model 92 implements the actual battery charging function,
minimizing recharge time while maximizing battery life. While the power
button can be used to manually turn off the Model 92, to conserve the
battery’s energy automatic shutdown will occur after ten minutes of
inactivity. Under software control, automatic shutdown will also occur
whenever the battery voltage reaches its minimal acceptable value. This
prevents the battery from reaching a deep-discharge condition. For
reliability under the less-than-gentle field environments the battery is
securely clamped within the Model 92’s enclosure. It’s expected that the
battery will provide correct operation for a period of three to five
years before replacement will become necessary. A competent technician
should be able to perform the task in well under 30 minutes.
Model 92 Specifications
Application: electrical testing of broadcast-standard
DT12-type cable assemblies
Connectors:
DT12 Cable Assemblies: one male and one female 37-pin circular
FK37-type
Fanout and XLR: one male and one female 3-pin XLR-type
Data Link: BNC
12 Volt DC Power In: coaxial power jack, 2.1 x 5.5 mm, locking bushing,
compatible with Switchcraft S760K plug
Power Source:
Internal: 12 volt 1.3 amp-hour sealed lead-acid battery. Operating
time 8 hours minimum with fully charged battery. Recharge time 8
hours maximum.
External: 12 volts DC nominal, acceptable range 10-15 volts DC; 250 mA minimum recommended for operation and battery charging. Units
shipped to North America and Japan include a 120 V input/12 Vdc
output power supply.
Master/Slave Operation:
Data Link: modified LIN bus, 1200 bit/s
Maximum Distance between Units: tested to 2400 feet using Belden
1694A coaxial cable and 4000 feet using standard CAT5E UTP
Dimensions:
Height: 5.0 inches (12.7 cm)
Width: 5.0 inches (12.7 cm)
Length: 11.0 inches (27.9 cm)
Overall Length: 12.5 inches (31.8 cm)
Weight: 5.5 pounds (2.5 kg)
Specifications
subject to change without notice.
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