User Guide
Issue 1, December 2006
This User Guide is applicable for serial numbers:
M92-00151 and later
with software version 1.04 and higher
Copyright © 2006 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
50035-1206, Issue 1
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Table of Contents
Introduction ..................................................................... 5
Overview ......................................................................... 8
Operation ........................................................................ 14
Technical Notes ............................................................... 20
Specifications .................................................................. 20
Appendix A—Error Code Definitions .............................. 21
Appendix B—DT12 Pinout Chart .................................... 22
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Issue 1, December 2006 Model 92 User Guide
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Introduction
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
Figure 1. Model 92 Top View
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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
DT12-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-toend 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. BNC connectors are 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
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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 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
Press and hold auto
test button to enable
continuous auto test.
Figure 2. Model 92 Configuration—Continuous Auto Test
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System mode LED will flash
to indicate that continuous
auto test is active.
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 deepdischarge 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.
Overview
Power On and Off
There are two ways that the Model 92 can
be brought to its operational state, i.e., be
“powered up.” One is manual and the other
is automatic. To manually apply power to
the Model 92 tap the power on/off button. A
short “power up” sequence will commence,
first testing the LED displays and indicators, and then briefly displaying the unit’s
software version number. The unit will then
display four dashes, indicating that testing
can now begin.
The Model 92 can also be powered up by
the presence of data on the master/slave
data link. This allows unattended operation
where the Model 92 unit that is designated
as the “master” can “wake up” its companion unit. The master unit will send out data,
“waking up” the slave unit. In this case the
normal power up sequence will take place,
with the exception that at the end of the sequence the unit will be forced into the slave
mode.
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No matter whether the Model 92 is manually
or automatically powered up, the voltage of
the internal rechargeable battery is automatically measured. A value of less than 10 volts
will result in a low battery message being
displayed. This is followed by the Model 92
automatically powering down. With a low battery condition, normal operation can’t take
place unless an external source of nominal
12 volts DC is applied. This power source will
allow Model 92 operation as well as charging
the internal battery. Maintaining the external
12 volt source for up to 24 hours may be
required to fully recharge the battery.
There are four ways that the Model 92 can
be “powered down.” One is manual and
three are automatic. The power on/off button
can be used to manually halt the unit’s operation; simply tap the power button. Pressing
and holding the on/off button while the unit
is operating will cause a change in the unit’s
operating mode rather than turning off the
unit.
The three automatic power down methods
are inactivity, master/slave command, and
low battery voltage. To maximize the Model
92’s battery operating time, automatic shutdown will occur after ten minutes of inactivity.
Technically, inactivity is defined as a continuous 10-minute period in which none of the
buttons are pressed. The only exception to
the inactivity timer is if the unit is operating
in the slave mode and data is present on
the master/slave data link. In this case, for
the Model 92 to automatically power down
requires that a power down command be
received by way of the master/slave data link.
The final way that the Model 92 will power
down is if a low battery voltage condition is
detected. Under software control, the battery
voltage is continually monitored. A measurement of lower than 10 volts will result in an
automatic power down.
For operator convenience, upon power down
three operating conditions are saved in nonvolatile memory: operating mode, connector
mode, and channel/pin mode.
Powering the Model 92
Internal Battery
The Model 92’s enclosure includes an internal 12 volt, 1.3 amp-hour, sealed lead-acid
rechargeable battery. This type of battery was
selected for two reasons: its ability to supply
peak current and long cumulative operating time. The LED-based displays used in
the Model 92 offer several nice operating
characteristics as well as one limitation. The
first positive is that they are very rugged and
should be able to meet the often-harsh conditions of field broadcast settings. A second is
that they provide a clear indication in low-light
conditions. However, as with most things one
must take the good with bad. The downside
of LED displays is that they require high peak
currents for effective operation. Standard
one-use (disposable) batteries, such as the
ubiquitous 1.5 volt AA style, would simply not
be suitable. The Model 92’s internal lead-acid
battery doesn’t have a problem supplying the
required peak current.
The energy capacity of the Model 92’s internal battery is such that cumulative operating
time in excess of eight hours can be expected
before recharging is required. In actual applications it can be expected that it will be
weeks, or even months, between required
charges.
External Power Source
An external source of nominal 12 volts DC
is required for Model 92 operation and battery
charging. The exact voltage value isn’t critical; anything in the range of 10 to 15 volts is
acceptable. Proper battery charging will
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always take place because circuitry contained within the Model 92 converts the incoming 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 milliampere, plug-in-the-wall power supply is
included with each Model 92. While good
quality, it’s a generic unit that can be easily replaced or substituted (Studio Technologies 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 correctly whenever an external power source is
connected. This flexibility is due to the presence 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 connected. The unit doesn’t have to be “powered up” for battery charging to take place.
The time required to fully recharge the battery 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 duration will probably be sufficient. The Model
92 implements a constant voltage charging
method. This minimizes the chance that battery overcharging will take place. Keeping
an external power source connected to the
Model 92 for long durations, or even permanently, 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 external source has been detected, the LED displays 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 details 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 indicator light is active. The selected system
mode will generally remain in effect until
it is manually changed. Power cycling the
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Figure 3. Model 92 Configuration—System Modes
Press and hold power
button to cycle through
system modes.
Model 92 will not cause it to change or revert
to a “default” setting. The exception
is in the master-slave situation where a
Model 92 configured for master-male active
or master-female active can “force” its companion unit into the slave mode.
Cable Modes
The Model 92 offers four cable modes. Refer
to Figure 4 for more details. The FK37 to
FK37 cable mode allows testing of DT12
assemblies that have a male FK37 connector on one end and a female FK37 connector on the other end. These are typically
referred to as “standard” DT12 cables. Refer
to Appendix B for DT12 wiring details. In the
FK37-M to XLR-F cable mode the Model 92
is ready to test DT12 cable assemblies that
have a male FK37 on one end and twelve
3-pin female connectors on the other. This
type of cable assembly is typically referred to
as a DT12 “fanout.” In the FK37-F to XLRM cable mode the Model 92 is configured
to test DT12 fanout assemblies that have a
female FK37 on one end and twelve 3-pin
male connectors on the other. The XLR to
XLR cable mode allows testing of standard
audio cables that have a 3-pin male XLR
connector on one end and a 3-pin female
XLR connector on the other end.
To select the desired cable mode is simple.
Press and hold the button to the left of the
up arrow; the Model 92 will slowly “cycle”
among the four choices. To select the
desired cable mode, release the up button when the appropriate indicator light
is active. The decimal point portion of the
displays is used to indicate the active cable
mode. The selected cable mode will remain
in effect until it is manually changed. Powering cycling the Model 92 will not cause it to
change or revert to a “default” setting.
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Press and hold
“up” button to
cycle through
cable modes.
Fanout:
FK37 female
to XLR male
Fanout:
FK37 male
to XLR female
FK37 to FK37
XLR to XLR
Figure 4. Model 92 Configuration—Cable Modes
Channel/Pin Mode
The Model 92 offers two basic ways of testing cable assemblies: channel mode
or pin mode. Refer to Figure 5 for details.
The channel mode is available for use in
all four of the cable modes: FK37 to FK37,
FK37-M to XLR-F, FK37-F to XLR-M, and
XLR to XLR. Channel mode is generally
appropriate for rapid field testing of existing inventory of DT12 and XLR cables. Pin
mode is only available in the FK37 to FK37
and XLR to XLR cable modes. It is not offered with the other two cable modes as it’s
not appropriate for use with DT12 “fanouts.”
In the channel mode DT12 testing is organized as twelve 3-conductor groups. The
3-conductors consist of a shield and a signal pair. In standard DT12 cable assemblies
these twelve channels are wired using pins
1 though 36 of FK37 connectors; pin 37 is
generally not used.
The pin mode is provided so that a detailed
view of the signal paths associated with a
cable assembly can be obtained. In the pin
mode testing can be performed on all 37
pins of a FK37 connector associated with a
DT12 assembly, although typically only pins
1 through 36 are utilized. Pin mode is useful
when fabricating new DT12 assemblies or
repairing cable assemblies which the channel mode has identified as being defective.
The button located to the left of the down
arrow is used to select between channel
mode and pin mode. Pressing and holding
this button for two seconds will cause the
mode to change between channel mode
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Press and hold “down” button to select
between channel and pin mode. Pin
mode is only available in the FK37 to
FK37 and XLR to XLR cable modes.
Figure 5. Model 92 Configuration—Channel/Pin Mode
The active cable mode
LED will flash when pin
mode is active.
and pin mode, or vice-versa. As previously
discussed, only when the cable mode is
selected for FK37 to FK37 or XLR to XLR is
it possible to select pin mode. The indicator
light associated with the active cable mode
is used to display whether channel mode or
pin mode is selected. When channel mode
is selected the light is lit steadily. The light
will flash to indicate that pin mode is selected. The selected mode, channel or pin, will
remain in effect until it is manually changed.
Powering down the Model 92 will not cause
this mode to change or revert to a “default”
setting.
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Operation
It’s now time to actually test cable assemblies using the Model 92.
Local Mode Operation
The following four sections provide details
on using the Model 92 when the system
mode is selected for local.
System Mode: Local
Cable Mode: FK37 to FK37
When the cable mode is selected to FK37
to FK37 the Model 92 is ready to test DT12
cable assemblies where both ends are terminated to FK37-type connectors. In this case
the cable-mounted FK37 connectors should
be mated with those on the Model 92. Ensure that the connectors are “locked” together using the threaded rings to ensure that
a reliable interconnection has been made.
Automatic or manual testing can now begin.
Tapping the auto test button will initiate
a rapid scan of all the channels or pins,
depending on whether channel or pin mode
is selected. At the end of the test sequence
one of three messages will display: ALL OK,
FAIL, or OPEN. ALL OK indicates that the cable assembly is ready to be placed into service. FAIL indicates that one or more failures
were detected during the test sequence.
If FAIL displays then manual testing of the
channels or pins should be used to identify
where the specific problem or problems are
located. OPEN indicates that no connections
were detected, most likely the result of one
or both of the FK37 connectors not being
correctly terminated on the Model 92.
sequentially tested and the result displayed
in real time. The left two digits of the display
will indicate the channel or pin being tested
while the right two digits will indicate the
result. In the channel mode the result will
be either OK or one or more of the nine
possible error codes. The label on the front
of the Model 92 contains a brief summary
of the error codes. A detailed description of
the error codes can be found in Appendix A.
In the pin mode the displayed result will be
the pin or pins that are connected. A oneto-one relationship between the pin being
tested and the connected pin is the desired
result. If no pin is detected as being connected to the pin selected for testing two
dashes (- -) will display. At the end of each
full test sequence a summary result will display: ALL OK, FAIL, or OPEN. The meaning
of the three possible results is the same as
with the auto test function, discussed in the
previous paragraph. After a slight pause to
display the summary result, the continuous
auto test mode will begin another complete
test of all the channels or pins. To cancel
continuous auto test simply press and
release the auto test, the channel up, or
the channel down select buttons.
At any time manual testing of individual
channels or pins is possible. The buttons
adjacent to the up and down arrows are
used to select the channel or pin to be
tested. The left two digits of the display will
indicate which channel or pin is currently
being tested. The right two digits will display
the results of the test. In the channel mode
the results will be either OK or one or more
of the nine possible error codes.
Pressing and holding the auto test button for
two seconds will initiate a continuous auto
test mode. The local mode LED will flash
when continuous auto test mode is active.
In this mode each channel or pin will be
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In the pin mode the light indicating that
FK37 to FK37 mode is active will flash. The
test results displayed will be the pin or pins
that are connected to the pin selected for
testing. If no pin is detected as being connected two dashes (- -) will display. Repeat
testing of the selected channel or pin will
take place every two seconds. The displayed results will refresh with each test
cycle.
System Mode: Local
Cable Mode: FK37-M to XLR-F
When the cable mode is selected for
FK37-M to XLR-F the Model 92 is configured
to test DT12 “fanouts” that have an FK37
male on one end and twelve 3-pin female
XLR connectors on the other.
Begin testing by connecting the fanout’s
FK37 male connector to the female FK37
connector located on the right side of the
Model 92. Ensure that a solid connection is
made by “locking” the connectors together
using the threaded ring. Each fanout channel can now be individually tested. Start by
plugging the fanout’s female XLR connector associated with channel 1 into the male
XLR connector located on the left side of
the Model 92. Use the buttons adjacent to
the up and down arrows to select channel
1 for testing. The left two display digits will
indicate the selected channel. The right two
display digits will indicate the test result.
The result will either display an OK or one
or more of the nine error codes. OK indicates that the connections associated with
channel 1 are correct. If the E1 error code is
displayed, be certain to use the channel
select buttons to manually “step through”
all channels looking for an OK result. This
will identify whether the fanout’s XLR connector has been labeled with the incorrect
channel number. After channel 1 has been
tested remove its associated female XLR
connector from the Model 92 and in its
place connect the connector associated
with channel 2. Use the manual channel
select buttons to select channel 2 for testing. Repeat this process for all twelve of
the fanout’s channels.
Note that in the FK37-M to XLR-F cable
mode only channel mode is available. In
addition, the auto test and continuous auto
test sequences are not available. Also, the
Model 92 doesn’t directly support fanouts
that contain a mixture of female and male
XLR connectors. In this case the use of
gender changers or “turn arounds” is
recommended.
System Mode: Local
Cable Mode: FK37-F to XLR-M
When the cable mode is selected for
FK37-F to XLR-M the Model 92 is configured
to test DT12 “fanouts” that have an FK37
female on one end and twelve 3-pin male
XLR connectors on the other.
Begin testing by connecting the fanout’s
FK37 female connector to the male FK37
connector located on the left side of the
Model 92. Ensure that the connection is
made solidly by “locking” the connectors
together using the threaded ring. Each
fanout channel can now be individually
tested. Start by plugging the fanout’s male
XLR connector associated with channel 1
into the female XLR connector located on
the right side of the Model 92. Use the buttons adjacent to the up and down arrows to
select channel 1 for testing. The left two display digits will indicate the selected channel. The right two display digits will indicate
the test result. The result will either display
an OK or one or more of the nine error
codes. OK indicates that the connections
associated with channel 1 are correct. If the
E1 error code is displayed, be certain to
use the channel select buttons to manually
“step through” all channels looking for an
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OK result. This will identify that the fanout’s
XLR connector has been labeled with the
incorrect channel number. After channel 1
has been tested remove its associated male
XLR connector from the Model 92 and in
its place connect the connector associated
with channel 2. Use the manual channel
select buttons to select channel 2 for testing. Repeat this process for all twelve of the
fanout’s channels.
Note that in the FK37-F to XLR-M cable
mode only channel mode is available. In
addition, the auto test and continuous auto
test sequences are not available. Also, the
Model 92 doesn’t directly support fanouts
that contain a mixture of male and female
XLR connectors. In this case the use of
gender changers or “turn arounds” is
recommended.
System Mode: Local
Cable Mode: XLR to XLR
In the XLR to XLR cable mode the Model 92
allows testing of standard audio cables that
use a 3-pin male XLR connector on one end
and a 3-pin female XLR connector on the
other. Begin by plugging the cable’s female
connector into the Model 92’s male connector, located on the left side of the unit. The
cable’s male connector should mate with
the female connector located on the right
side of the Model 92. Testing can take place
in either the channel mode or the pin mode.
In the channel mode the left two display
digits will always show XL, indicating that
the XLR to XLR cable mode is active. The
right two digits will either show OK or one or
more of the nine error codes.
In the pin mode the light indicating that
XLR to XLR mode is active will also flash. In
this mode the left two digits will display the
pin selected for testing. The exact text will
be X1, X2, or X3, indicating XLR connector
pins 1, 2, or 3. The up and down buttons
are used to select the desired pin. The right
two digits will show the pin or pins that are
connected to the pin selected for testing.
Repeat testing of the cable, when in channel mode, or the specific pin, when in the
pin mode, will take place. The displayed
results will refresh with each test cycle.
Master/Slave Mode Operation
A challenge is encountered when testing
cable assemblies where both ends can’t
be physically connected to one Model 92.
This occurs in cases such as where DT12s
are permanently installed in stadiums and
arenas, or when portable cabling has been
“run” and can’t be accessed easily. Using
two Model 92 units, virtually any DT12 cable
assembly, fan out, or even 3-pin XLR cables
can be tested.
The master/slave mode is created in the
Model 92’s hardware and software so that
the unit’s functions are “split” into a sendtest-signals portion and a receive-testsignals portion. A communications link is
established between two Model 92 units,
allowing the two functions, send and receive, to work together. The data passing
in each direction on the data link effectively
“couples” the two Model 92 units into one.
One unit is designated as “master” and coordinates the activities of a test. The “slave”
unit follows the commands of the master,
performing the actions requested and returning test results as required.
Master/slave testing operation is quite easy
to initiate and use. But the flexibility provided by the Model 92’s multiple operating
modes can be a bit tricky to get one’s head
around. While this user guide will document
the basic “hows and whys” of master/slave
Issue 1, December 2006 Model 92 User Guide
Page 16 Studio Technologies, Inc.
operation, only experience can serve as the
best teacher. It’s recommended that some
“bench” experimentation be done prior to
going full bore out in the field.
Master/Slave Data Link
For two Model 92 units to be used in a
master/slave arrangement they must be
interconnected with a 2-conductor signal
path. This connection is referred to as the
master/slave data link. It supports the transmission of bi-directional serial data as well
as linking the power supply common connections of both units. A BNC connector
is used for the master/slave data link. This
type of connector was selected not because
of a specific technical requirement, but
because of its wide popularity in the broadcast and video industry. In many applications where DT12 cable assemblies are to
be tested there will also be BNC-terminated
video cables present. This will most likely
allow the easier method of interconnecting
two Model 92 units. However, there’s no
reason that other types of cable can’t be
used. Options can include shielded microphone cable and twisted pair telephone
cable. While using coax will allow the greatest distance between Model 92 units, even
twisted pair has been tested at over 4000
feet! This should be well in excess of the
length of any DT12 cable assembly that
needs to be tested.
It’s important to note that two metallic connections must be made between the master
and slave Model 92 units. When using a
coaxial cable the two metallic connections
would consist of the inner conductor and
the shield. Alternately pins 2 and 3 of a
standard audio cable that uses XLR connectors would serve the purpose. However, any
transformers, “baluns,” or capacitors in the
connection path that provide DC isolation
will prevent master/slave operation.
After interconnecting two Model 92 units, it’s
quite easy to confirm that the master/slave
data link has been established. Temporarily
designate one of the units as slave. Be sure
that it is powered down. Turn on the other
(master) unit by tapping its power button.
Then press and hold its power button until
the system mode has changed to mastermale active or master-female active. At this
point if the connection is valid data coming from the master Model 92 will “wake
up” the slave unit. The active LED, located
below the BNC connector, on each unit will
flash as data packets move between the
units. Once data link operation has been
confirmed power down the unit designed
as master. The slave unit should also power
down in response to a command from the
master unit.
Note that maintaining a short circuit on
the Model 92’s data link BNC connector
is something to avoid. Due to an idiosyncrasy in the operation of the data communications transceiver integrated circuit an error
in the data link wiring can force the Model
92 to stay in the powered up state. The
10-minute inactivity timer will not be able to
power down the unit; nor will a low-batteryvoltage condition be able to invoke a power
down either. Damage to the battery will
occur if a deep discharge state is reached.
This situation is not something that the
Model 92’s designers are especially proud
of, but they weren’t aware of the condition
until it was too late to make a change. And
contacting the world-class maker of the integrated circuit didn’t get much of a response
except “hmmm…” So in conclusion, as long
as the BNC connector isn’t presented with a
short circuit or a low impedance load condition things will work fine.
Model 92 User Guide Issue 1, December 2006
Studio Technologies, Inc. Page 17
Master/Slave Cable Testing
Once the data link has been established
between the two Model 92 units testing
operation can begin. Start from the condition of having both units in their powered
down state. Then review the desired testing
scenario, knowing exactly which cable assembly is going to be tested first. Designate
one of the Model 92s as the master unit.
There’s no requirement as to which unit is
the master and which unit is the slave. Typically the Model 92 that’s most conveniently
accessible should be the master unit. For
example, when testing DT12s in a stadium,
it probably makes sense to have the master
situated in the truck dock or main wiring location. Then the slave unit can move among
the destination locations such as the broadcast booth, side of the field, etc.
Now activate power to the unit that has
been designated as master. Ignore the status of the data link active LED and whether
or not the slave unit powers up. Before
these issues come into play a couple of other things must first be accounted for. On the
master unit, set the cable mode to match
the type of cable to be tested. If, for example, the cable to be tested has FK37-type
connectors on each end select the cable
mode as FK37 to FK37. Another example
would be if the cable to be tested has an
FK37 female on one end that “breaks out”
into twelve XLR males on the other end.
This would necessitate setting the master
unit’s cable mode to FK37-F to XLR-M.
The final step is to set the master unit’s
system mode. This is a little tricky to understand but we’ll work through it! Begin
by confirming the exact type of connector
that is to be connected to the master unit.
For example, while the cable mode might
be set for FK37 to FK37, there’s no requirement as to which connector end, male or
female, is physically located near the Model
92 that’s been designated as master. For
our example let’s specify that an FK37 male
connector is on the end of the cable that’s
to be attached to the master Model 92 unit.
To meet the needs of this situation, set the
master unit’s system mode for MasterFemale Active. This is accomplished by
pressing and holding the power on/off
button until the desired system mode is
enabled.
At this point the master unit is configured
to perform the required cable test. To
review, the cable mode has been set to
match the type of cable to be tested and the
system mode has been selected to activate
the connector type required for the test
environment.
Once configured to the desired system
mode, the master Model 92 should have
caused the slave Model 92 to power up.
The master/slave data active LEDs on both
units should indicate that data is passing
back and forth. The slave Model 92 should
have its system mode LED indicating that
slave mode is active. The auto test and
manual channel select (up and down) buttons on the master unit perform the same
functions as if the local system mode was
selected. On the slave unit the auto test and
manual channel select buttons are disabled.
The power on/off button on the slave unit
remains active but isn’t generally utilized
during master/slave operation.
Connect the cable to be tested to the master and slave Model 92 units. In the example
covered a few paragraphs previously, an
FK37 male would be connected to the
master Model 92. An FK37 female would
be connected to the slave Model 92. Testing functions can only be controlled by the
master Model 92. However, the test results
Issue 1, December 2006 Model 92 User Guide
Page 18 Studio Technologies, Inc.
will display on both the master and slave
Model 92 units. This ensures that someone
assisting at the slave position is kept “in the
loop” about the testing process. To the user,
the master unit should “look and feel” just
as if it was set for local system mode. The
auto test, continuous auto test, and manual
channel or pin tests can be used as desired.
After testing has been completed powering down the master Model 92 will also
cause the slave Model 92 to power down.
An inactivity timer shutdown of the master
Model 92 will also cause the slave unit to
power down. Manually powering down the
slave Model 92 will cause the unit to shut
down and end any tests in progress. But the
unit will immediately power on again in response to the master unit data commands.
Only by disconnecting the data link connection can the slave unit be independently
turned off. (But this isn’t something that one
would typically want to do anyway!)
“Jumper” Cables
In many cases it will probably be necessary
to use DT12 or 3-pin XLR “jumper” cable
assemblies to connect the master and slave
Model 92 units to the cables to be tested.
For example, a flexible DT12 cable assembly might be required to connect a panelmounted (bulkhead) FK37 connector to a
Model 92. In this case be certain that the
cables that are going to be part of the test
setup are themselves tested first using the
Model 92’s local system mode. Don’t add
variables to an already fairly complicated
situation!
Ten Steps to Success
With some practice master/slave mode
operation should become second nature.
The key is to follow a logical setup and
configuration sequence before attempting
to test a cable assembly. This will make testing a simple matter, rather than leading to
a confusing situation! The steps might be
organized as follows:
1. Deploy two Model 92 units at the ends
of the cable or cables to be tested.
2. Establish the data link connection and
confirm that it’s functioning correctly.
3. Turn off both units.
4. Designate one unit as master and power
up that unit.
5. On the master unit, select the cable
mode as required for the cable under
test.
6. Identify the type (sex) of the connector
to be connected to the master unit.
7. On the master unit, select the system
mode (master-male active or masterfemale active) so as to activate the
connector that will mate with the cable
to be tested.
8. Confirm that the slave unit has automatically powered up and its system mode is
set for slave.
9. Connect the ends of the cable to be
tested to both the master and slave
units.
10. Use the buttons on the master Model 92
to perform the desired tests. The displays on both the master and the slave
units will display the test results.
Model 92 User Guide Issue 1, December 2006
Studio Technologies, Inc. Page 19
Technical Notes
Specifications
Theory of Operation
At its core the Model 92 uses a fairly simple
method to test the signal paths of the connected cables. Under software control a test
signal can be assigned to any one of the 37
pins of the male FK37 connector and the
three pins of the male XLR connector. This
test signal is a DC level of approximately
4 volts which is created by way of a pulsewidth-modulator output on the microcontroller. Again under software control, the DC
level of signals present on the 37 pins of the
female FK37 connector and the three pins of
the female XLR connector can be measured.
An analog-to-digital converter input on the
microcontroller measures the actual voltages. All signals are generated and measured
in reference to the power supply, battery,
and data link common connection.
Resistors, in series with each of the male
and female connector pins, along with other
protection circuitry limit the current that can
come into or go out of the Model 92. This will
prevent most external DC or static-discharge
signals from damaging the Model 92.
The Model 92’s channel and pin test routines
specify which male (output) pin is active and
then scans the female (input) pins, measuring the voltage present on each pin. The
data is analyzed and interpreted so as to
provide meaningful results to the user.
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 and information contained in this User
Guide subject to change without notice.
Issue 1, December 2006 Model 92 User Guide
Page 20 Studio Technologies, Inc.
Appendix A
Error Code Definitions
In this section a detailed description will be
given of the Model 92’s nine error codes.
The error codes are only displayed when
the Model 92 is selected for the channel
mode and an issue is detected. In the channel mode the three conductors associated
with a DT12 channel are tested for shorts,
opens, and proper connectivity. All the tests
are made in relation to the pins associated
with the specific channel on the FK37-type
connectors.
E1: Open Shield and Pair
No connections have been detected on the
shield, signal low, and signal high paths of
the channel selected for testing. The channel is completely “open.”
E2: Open Shield
No connection has been detected on
the shield path of the channel selected for
testing.
E3: Open Pair
No connection has been detected on the
signal low path, the signal high path, or
both the signal low and signal high paths.
E4: Reversed Pair
The signal path has been reversed or
“flipped.” The signal low connection on the
female connector end of the cable under
test is connected to the signal high connection on the male connector end of the cable
under test. And, as expected, the signal
high connection on the female connector
end of the cable under test is connected to
the signal low connection on the other end.
E5: Shorted Shield to Pair
A connection has been detected between
the shield path and the signal low path,
between the shield path and the signal high
path, or between the shield path and both
the signal low and signal high paths.
E6: Shorted Pair
A connection has been detected between
the signal low path and the signal high path.
E7: Incorrect Shield Connection
The shield pin on the female connector end
of the cable under test is connected to the
pin designated for signal low or signal high
on the male connector end of the cable
under test.
E8: Incorrect Pair Connection
The signal low pin or the signal high pin on
the female connector end of the cable under test is connected to the pin designated
for shield on the male connector end of the
cable under test.
E9: Channel-to-Channel Error
This is a somewhat general-purpose error
code. It indicates that one or more problems exist between the pins associated with
the selected channel on the female connector end of the cable under test and pins
associated with other channels on the male
end of the cable.
Model 92 User Guide Issue 1, December 2006
Studio Technologies, Inc. Page 21
Appendix B
DT12 Pinout Chart
FK37 DT12 DT12
Pin Number Channel Function
1 SHIELD
5 1 +
6 –
2 SHIELD
3 2 +
7 –
4 SHIELD
8 3 +
9 –
10 SHIELD
16 4 +
17 –
11 SHIELD
12 5 +
18 –
13 SHIELD
19 6 +
20 –
14 SHIELD
15 7 +
21 –
23 SHIELD
24 8 +
29 –
25 SHIELD
30 9 +
31 –
26 SHIELD
27 10 +
32 –
22 SHIELD
28 11 +
33 –
34 SHIELD
35 12 +
36 –
37 --- ---
Issue 1, December 2006 Model 92 User Guide
Page 22 Studio Technologies, Inc.
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