6
TS25D Test Set
Users Guide
Modes and Functions
Warning
When testing circuits which are close to a
battery source, the pops in the handset
receiver that result from clipping onto a line
may be quite loud. Although there is
protection against acoustic shock built into
the test set, if the receiver is held tightly
against the ear, acoustical shock may occur.
Monitor Mode
Monitor mode is primarily for audio monitoring of the
Tip and Ring pair while on hook. In Monitor mode, the
test set has a high input impedance, which allows
monitoring of the line without disrupting
conversations or data signaling if present. The test set
draws no direct current from the line and it transmits
no signals to the line. Also, in Monitor mode, the TS25D
monitors for high-speed data signals on the line. If the
test set detects data it will display
DATA DETECTED
on
the LCD. If there is no high- speed data on the line, the
LCD will display
NO DATA
.
In Monitor mode, the test set is typically used to
perform one or more of the following procedures:
•
Verification that a line is idle when looking for a
line to borrow
•
Listening for noise on the line
•
Performing a test for the presence of high
frequency data on the line
•
Measuring the DC voltage from Tip to Ring
•
Detecting DTMF signals
•
Monitoring line polarity
The TS25D will respond to incoming ringing signals
when it is in Monitor mode. It does not detect ringing
signals when it is off.
Talk Mode
When the test set is connected to a working analog
telephone line and is switched to Talk mode, the test
set will go off-hook and draw dial tone. An off-hook
TS25D test Set works like a standard telephone. When
off-hook, the test set is used to perform its main
purpose, which is to verify the proper operation of
analog voice telephone lines or to establish temporary
communications on a “borrowed” pair.
In both Talk and Monitor mode you can change the
receiver’s volume level by pressing the Up or Down
arrow keys.
Each time the test set is switched to Talk mode, it
quickly tests the line for high-speed data and for DC
voltage before it goes off-hook. If there is no high-
speed data on the line, and there is enough DC voltage
to go off-hook on (>3 V), the test set will go off-hook
without you ever noticing that the tests have been
performed.
Occasionally you may run into the situation where you
have accidentally connected to a line carrying high-
speed data or where you have connected to a line with
either too little or too much DC voltage to go off-hook
on. The data and voltage tests are designed to detect
these conditions and are discussed in the following
sections.
Data Lockout
When the test set is switched to Talk mode, it tests the
line for high-speed data signals and for DC voltage
before it goes off-hook. If data is detected in the
frequency band from 20 kHz to about 1 MHz, the test
set will refuse to go off-hook and the LCD will display
DATA DETECTED
,
DOWN ARROW TO OVERRIDE
. This
mode is called Data Lockout mode. In the Data Lockout
mode, the test set is kept on-hook, “locked out”,
despite having been switched to Talk Mode. Data
Lockout Mode prevents accidental corruption of data
transmissions while working in modern
telecommunications cable environments that have a
mix of analog telephone and data services.
