9
Physical Characteristics
PULSE key The PULSE key switches the test set between tone and pulse dialing. The PULSE
key is active only when the test set is off-hook. Any time the test set goes off-
hook, it is automatically set to tone dialing. Once off-hook, press the Shift
(STORE PROG) key and then the PULSE key to change the dialing mode to pulse
dialing.
Vdc/mA TEST
key
When you press the Vdc/mA TEST key, one of two tests is performed depending
on the operating mode of the test set. If the test set is in Monitor mode and you
press the Vdc/mA TEST key, the Vdc (dc voltage) test will be executed. If the test
set is in Talk mode (off-hook) and you press the Vdc/mA TEST key, the mA test
(loop current) will be executed.
To run the Vdc test, put the test set into Monitor mode and connect it to Tip and
Ring of the POTS line you want to measure. Then press the Vdc/mA TEST key.
The test set measures the dc voltage across Tip and Ring and the measured
voltage (0-140 Vdc) is shown on the display. Normal line voltage is between 42
and 54 V dc.
To run the mA test, connect the test set to Tip and Ring of the POTS line you
want to measure and take the test set off-hook. Then press the Vdc/mA TEST
key. The test set measures the dc loop current that it is drawing from the line.
The measured current (0-120 mA) is shown on the display. Normal loop current
is above 23 mA. If the loop current is too low, the telephone line you are testing
may not be able to supply enough current to power the customer’s telephone
devices and you may want to perform some additional testing on that line.
The purpose of these tests is to allow you to make a quick assessment of
whether or not the line you are working on has normal CO battery voltage or
normal loop current. If the voltage is below 2.5 V dc, there is not enough
voltage for the test set to go off-hook. If the voltage is above 140 V dc, this is
potentially dangerous to you and the test set. If you encounter this, carefully
remove the test set’s clip leads from the line. Be sure to hold the clip leads by
their insulated boots and avoid touching the clip lead’s metal parts with your
hands. Be careful to avoid shorting the clip leads to each other. See "High
Voltage Lockout Operation" on page 15.
Low Battery
icon
When the 9 V battery is nearly discharged, no bars are shown on the battery
icon on the display. Replace the battery immediately when this occurs. See
"Replacing the Battery" on page 20.
Polarity icon The polarity icon indicates the polarity of the dc voltage across the line’s Tip and
Ring wires is reversed. If the test set’s red clip lead is connected to a more
positive voltage than its black clip lead (reverse polarity), the icon is shown on
the display. If the test set’s red clip lead is connected to a more negative voltage
than its black clip lead, no icon is shown.
Table 2. Display and Keypad (continued)
Key or
Indicator Description (refer to Figure 3)
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