14 Using the Multimeter
1. Set the function selector to 150
mA DC mA.
2. Remove power from the circuit
under test and discharge all
capacitors.
3. Break the electrical path for the
circuit in which you want to mea-
sure current. Then connect the –
(common) test lead to the nega-
tive side and the positive (+) test
lead to the positive side of the
circuit.
4. Apply power to the circuit.
5. Read the lower line of ACVA/
DCVA on the multimeter, then
multiply that reading by 50 to
compute the current.
For example, if the needle points
to 2, the DC current is 2 × 50 =
100mA. If the needle points to 1,
the DC current is 1 × 50 = 50mA.
Measuring AC Current in a Wire
WARNING: DO NOT APPLY VOLT-
AGE TO THE TEST LEADS WHILE
THE FUNCTION SELECTOR IS SET
TO ACA.
Important: Make sure you place only
one wire inside the ammeter's jaws at
a time. If you try to measure AC cur-
rent in more than one wire at a time,
such as an AC power cord of a
household appliance, the measure-
ment will not be accurate.
1. Connect the ammeter to the mul-
timeter (see “Connecting the AC
Ammeter to the Multimeter” on
Page9).
2. Set the function selector to ACA.
3. Test the ammeter by sliding T/3A/
15A/30A on the ammeter to T,
then reading the line below
AC15V on the multimeter.
If the needle points to GOOD on
the multimeter, the ammeter is
working. Skip to Step 4. If the
needle points to FAIL on the mul-
timeter, check the multimeter’s
battery (see “Installing a Battery”
on Page8), then repeat Step 3. If
the needle points to FAIL again,
take the multimeter to your local
RadioShack store.
OHMS