Kopp GDT 190 A Manuel D'utilisation page 8

DC Voltage Measurement
1) Set the function/range switch to the DC voltage range.
2) If the polarity of the circuit to be tested is known, touch
the black test lead to the neutral side. If the polarity is
unknown, touch the test leads to opposite sides of the
circuit. If the test leads are reversed, the "(-)" indicator
will appear on the display. Reverse the test leads for proper
polarity and read the value indicated on the display.
Common DC Voltage Measurements
Automotive Batteries
Set the function/range switch to the 20 volt DC setting. First
check the quality of the battery terminal connector by touching
the red (+) test lead to the connector while touching the black
(-) test lead to any bare metal framework of the vehicle. The
tester should read 12 volts or higher with all of the vehicle
accessories turned off. If the display fluctuates rapidly, this
could indicate a bad terminal connection. Remove the terminal
connectors and clean both terminals and connectors tho-
roughly. For improved conductivity and corrosion resistance,
coat the terminals and connectors with GB #OX-100 anti-
oxidant compound (available at your local hardware store).
Replace and tighten the terminal connectors. Secondly, if the
terminals and connectors are making good contact, touch the
test leads to the battery and vehicle framework as described
above (see fig. 2). Note the reading of the meter. Get an assis-
tant to turn on the headlights while the test leads are making
contact. The reading should drop a few volts. Should the
reading drop 5 volts or more, the battery should be charged
or possibly replaced if the voltage drop is significant. The
circuit may need to be checked further for problems within the
electrical system that may be draining the battery.
Household Batteries
Set the function/range switch to the 20 volt DC setting. Touch
the red (+) lead to the (+) terminal of the battery and the black
(-) lead to the (-) terminal of the battery. Read the voltage level
of the battery on the display. Generally speaking, if a battery's
output voltage falls below 60% - 70% of its original rating, it
should be replaced.
DC 10 Amp Measurement
A separate input jack is provided for measurement of DC cur-
rent up to 10 Amps. This range is not fused so it is imperative
that the circuit under test does not exceed 10 Amps. Addi-
tionally, this function is designed for intermittent use only.
Maximum contact time of the test leads with the circuit is 15
seconds, with a minimum intermission time of 30 seconds
between tests.
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