Manual Ranging Multimeter (220-0181A) Operation Faxback Doc. # 7174
INSTALLING BATTERIES
Your meter requires 3 AA batteries for power. We recommend alkaline
batteries, such as Radio Shack's Cat. No. 23-552.
WARNING: TO AVOID ELECTRIC SHOCK, DISCONNECT BOTH TEST LEADS FROM ANY
EQUIPMENT BEFORE YOU REMOVE OR INSTALL THE BATTERIES.
Follow these steps to install batteries.
1. Turn off the power by setting the power switch to OFF. Then
disconnect the test leads from the meter.
2. Open the battery/fuse compartment cover by pushing the cover's tab in
the direction of the arrow and lifting off the cover.
3. Install the batteries as shown by the polarity marks (+ and -) and
illustration inside the battery compartment.
4. Replace the compartment cover.
WARNING: DO NOT OPERATE THE METER UNTIL YOU CORRECTLY INSTALL THE
BATTERIES AND CLOSE THE BATTERY COMPARTMENT COVER.
When the batteries become weak, the display becomes dim. Replace all
batteries. Remove the batteries when you will not use the meter for a
week or more. Never leave weak or dead batteries in your meter. Even
leak-proof batteries can leak damaging chemicals.
USING TEST LEADS
Use only the type of test leads supplied with your meter. These leads are
rated for 1200 volts.
Cautions: Although these test leads are rated for 1200 volts, the maximum
rating of this meter is 1000 volts DC and 750 volts AC. Do not
try to measure any voltage that exceeds these ratings. Use
extreme caution when you use high-voltage ranges.
Be sure you always select the correct function before you
attach the test leads to the circuit to be measured. You can
blow one or more fuses if you rotate the function control while
there is current or voltage present.
MAKING MEASUREMENTS
TURNING ON THE METER
To turn on the meter, set OFF/ON to ON.
UNDERSTANDING PHANTOM READINGS
If you do not connect the meter's probes to a circuit, and select DC or AC
volts, the display might show a phantom reading. This is a wandering
effect produced by the meter's high input sensitivity and is normal for
most high-quality, high-impedance meters. When you connect the probes to
a circuit, a real measurement appears.
OVERRANGE INDICATION
The following display appears when the measurement exceeds the selected
range. If you are measuring volts or amps, disconnect the meter from the
circuit you are measuring or change the meter's measuring range.
Notes: The meter displays the overrange indication or a measurement
around 0 if it blows a fuse while measuring current in the mA
range.
If the meter displays the overrange indication when you measure AC
current, and the circuit does not exceed the AC current in the
present range, the circuit is exceeding the meter's DC rating.
For example, if you try to measure a DC power supply's AC ripple
current, the signal has both an AC and DC component. If the DC
component exceeds the meter's rating, the meter displays the
overrange indication. To measure this current, you must
externally block the DC component.
The AC current modes do not use an AC coupling capacitor to block
DC. Both DC and the AC current flows through the shunt
resistance. Too much DC current overpowers the AC component. If
you need to measure the AC component of a DC signal, we suggest
you use a high-quality capacitor to block the DC component. For
normal AC line frequencies, we suggest you use a .47 microF or
larger capacitor.
MEASURING DC VOLTAGE
WARNING: DO NOT TRY TO MEASURE A VOLTAGE GREATER THAN 1000 VOLTS DC AND
750 VOLTS AC (RMS). YOU MIGHT DAMAGE YOUR METER AND EXPOSE
YOURSELF TO A SEVERE SHOCK HAZARD.
Follow these steps to measure a DC voltage.
1. Set the function control to one of the DC V ranges. The selected
range appears on the display.
2. Plug the black test lead into the meter's -COM terminal, and plug
the red lead into the meter's + terminal.
3. Connect the black test probe to the COMMON point for the voltage to
be measured. Connect the red test probe to the voltage you want to
measure.
Notes: If the display shows an overflow indication, set the function
control to a higher position.
If a minus sign (-) appears, the red probe is measuring negative
voltage in reference to the black probe.
MEASURING AC VOLTAGE
WARNING: DO NOT TRY TO MEASURE A VOLTAGE GREATER THAN 750 VOLTS AC. YOU
MIGHT DAMAGE THE METER AND EXPOSE YOURSELF TO A SEVERE SHOCK
HAZARD.
Follow these steps to measure AC voltage.
1. Select AC volts by rotating the function control to one of the
AC V ranges. V or mV appears on the display.
2. Plug the black test lead into the meter's -COM terminal, and plug the
red lead into the meter's + terminal.
3. Connect the probes to the voltage you will measure.
Notes : If the display shows an overflow indication, set the function
control to a higher position.
This calculated measurement usually takes about 4 seconds to
complete but can take up to 10 seconds.
MEASURING AN AC VOLTAGE ON A DC BIAS
This meter contains a DC blocking capacitor, which lets AC voltage pass
through it, but blocks DC voltages. If the meter is in an AC voltage
range, the DC blocking capacitor is enabled.
To measure an AC voltage superimposed on a DC voltage source bias, follow
the steps on Page 17 and 18.
Warning: NEVER TRY TO MEASURE AN AC VOLTAGE THAT IS RIDING ON A DC
VOLTAGE LEVEL WHERE THE PEAK AC VOLTAGE EXCEEDS 1000V WITH
RESPECT TO EARTH GROUND.
MEASURING 3-PHASE AC VOLTAGES
We designed this meter to measure household AC voltage. It is not for
commercial or industrial use. If you want to measure 3-phase,
line-to-line voltages, please note the following:
Because of the dangers inherent when you measure three-phase circuits,
we strongly recommend you do not use this meter for such applications.
Do not exceed the maximum RMS AC rating (750 VAC).
If you choose to make the measurements, use extreme caution. The
highest possible voltage is much greater than the voltage between any
point in the circuit and ground.
To determine line-to-line voltage, measure between the circuit and a known
ground point. Then multiply the result by 1.732.
For example, if you measure a voltage of 462 volts between a point in the
circuit and ground, the possible line-to-line voltage is 800 volts.
462 Volts x 1.732 = 800 Volts
This voltage exceeds the meter's range and you should not connect the
meter to the circuit or to any equipment connected to the circuit. Doing
so could present a dangerous shock hazard and damage the meter.
Hint: When you use the meter to probe for a voltage in a high-voltage
circuit, do NOT try to position both probes at the same time.
Instead, clamp the black lead to the neutral or ground circuit lead
(usually a bare, green, or white lead) using an insulated Slip-On
Alligator Clip (Cat. No. 270-354) and probe for voltages with the
red lead. (Other clips include a Wire-Piercing Probe Adapter-
278-715 - and a Mini Test Clip Adapter - 270-334A.)
You need to concentrate on only one test probe, so place your free hand in
your back pocket or behind your back. This helps prevent you from
accidentally touching a hot wire (usually red, black, or blue) with that
hand.
WARNING: IF YOU CLAMP ONTO A HOT WIRE AND TOUCH A CONNECTED TEST PROBE AT
THE SAME TIME, YOU COULD RECEIVE AN ELECTRIC SHOCK.
MEASURING AC/DC CURRENT
To measure current, break the circuit and connect the leads in series with
the circuit. Never connect the leads across a voltage source (in
parallel). Doing so can blow the fuse or damage the circuit under test.
The maximum current input limit is 10A.
WARNINGS:
DO NOT APPLY VOLTAGE DIRECTLY ACROSS THE INPUT TERMINALS WHILE IN THE
CURRENT MODE. YOU MUST CONNECT THE METER IN SERIES WITH THE CIRCUIT.
THE 10A INPUT TERMINAL IS NOT FUSED. A SEVERE FIRE HAZARD AND SHORT
CIRCUIT DANGER EXISTS IF YOU APPLY A VOLTAGE WITH HIGH CURRENT
CAPABILITIES TO THIS TERMINAL. YOU ALSO COULD DESTROY THE METER.
1. Set the function control to one of the A (DC amps) or A (AC amps)
ranges. mA or A appears on the display.
2. Select the correct input jack for the scale you will use.
Use the 400/40mA jack or 4mA jack for levels up to 400mA. Use the
10A jack for levels over 400 mA.
3. Remove power from the circuit under test. Then break the circuit at
the appropriate point.
4. Connect the probes in series with the circuit.
5. Apply power to the circuit.
Note: If the measurements exceed the selected range, an overrange
indication appears. Use the function control to select a higher
range, or connect the red test probe to a more appropriate jack.
Notes: If you set the meter for DC current, the minus (-) sign appears or
disappears to the left of the bargraph to show the polarity of the
measured current.
The 400 mA and the 4 mA ranges are fuse-protected. The 10A range
is not fuse-protected.
The meter displays the overrange indication or 0 if it blows a
fuse while measuring current in the fuse-protected range.
If the meter displays the overrange indication when you measure
AC current, and the circuit does not exceed the AC current in the
present range, the circuit is exceeding the meter's DC rating.
For example, if you try to measure a DC power supply's AC ripple
current, the signal has both an AC and DC component. If the DC
component exceeds the meter's rating, the meter displays the
overrange indication. To measure this current, you must
externally block the DC component.
The AC current modes do not use an AC coupling capacitor to block
DC. Both DC and AC current flow through the shunt resistance.
Too much DC current overpowers the AC component. If you need to
measure the AC component of a DC signal, we suggest you use a
high-quality capacitor to block the DC component. For normal AC
line frequencies, we suggest you use a .47 microF or larger
capacitor rated for the voltage involved (500 volts or greater).
Caution: Do not apply voltage directly across the input terminals while
in the current mode. You must connect the meter in series with
the circuit to prevent damaging the meter.
Warning: The 10A input jack is not fused. A severe fire hazard and
short circuit exists if a voltage with high current capabilities
is applied to these terminals. This can destroy the meter.
MEASURING RESISTANCE
WARNING: BE SURE THE CIRCUIT UNDER TEST HAS ALL POWER REMOVED AND ANY
ASSOCIATED CAPACITORS ARE FULLY DISCHARGED BEFORE YOU MAKE A
RESISTANCE MEASUREMENTS.
The resistance measuring circuit compares the voltage gained through a
known resistance (internal) with the voltage developed across the unknown
resistance. So, when you check incircuit resistance, be sure the circuit
under test has all power removed (all capacitors are fully discharged).
1. Set the function control to one of the Ohms ranges. Ohms appears on
the display. If there is no resistance connected to the meter, the
display shows an overrange indication.
2. Plug the red test lead into the + jack and the black test lead into
the -COM jack.
3. Connect the probes across the circuit to be measured, or plug the
resistor under test into the - ohm/diode/capacitance + socket.
If the resistance is greater than 1 megohm, the display takes a few
seconds to stabilize. This is normal for high-resistance
measurements.
Notes: As with the voltage range, use the measuring unit display and the
control's position to determine the current resistance range. If
only Ohms appears on the display, the values of the measurements
are in ohms. If K and Ohms appear, the meter is measuring kilohms
(the reading x 1000). If M and Ohms appear, the meter is
measuring megohms (the reading x 1,000,000).
The meter has a fuse and a special circuit that protects the
resistance ranges from over-voltage (voltages greater than 5
volts). If you blow the meter's fuse, the meter does not operate
correctly in the ohms mode. Check the fuse if the meter displays
0 for all resistance measurements, or if it displays other unusual
readings.
When you touch the ends of the test probes together, the meter
displays a small value. This value is the resistance of the test
leads. Note this value and subtract it from the measured value
when you measure a very small resistance.
Checking Continuity
Your meter has a built-in audible continuity function. Follow these steps
to check a circuit's continuity.
1. Set the function control to CONT. CONT and Ohms appear on the
display.
2. Connect the red test lead to the + jack and the black test lead to the
-COM jack.
3. Connect the probes to the circuit you want to test.
Notes: If the circuit's resistance is less than or equal to 50 ohms, the
buzzer sounds. If the resistance is greater than 50 ohms, but
less than 400 ohms, the meter displays the circuit's resistance
and the buzzer does not sound. The meter shows an overrange
condition if the resistance is 400 ohms or greater.
The resistance measurement will always be more accurate in the
ohms (ohms) mode than in the CONT mode.
CHECKING DIODES
This function lets you check diodes and other semiconductors for opens and
shorts. It also lets you determine the forward voltage for diodes. You
can use this function when you need to match diodes.
1. Set the function control to the Diode Symbol. The Diode Symbol
appears on the display.
2. Plug the red test lead into the + jack and the black test lead into
the -COM jack.
3. Remove power from the circuit under test.
4. Connect the probes to the component you want to check and note the
display. Or, connect the component you want to test to the
- ohm/diode/capacitance + test socket and note the display.
5. Reverse the probes or reverse the component in the socket, and note
the second reading. If one value is normal and the other is
overrange, the component is good. If both values are overrange,
the component is open. If both values are very small or zero, the
component is shorted.
Notes: When the diode is reverse biased, the display shows the normal
overrange indication.
If the display shows a low-voltage reading, the red test probe is
at the anode of the diode and the black probe is at the cathode
(banded side) of the diode. This is called the forward biased
condition.
If the diode is in a forward biased condition and if you use the
- ohm/diode/capacitance + socket to test the diode, the anode is
at the + side of the socket and the cathode is at the banded (-)
side.
CHECKING TRANSISTORS
Follow these steps to determine a transistor's gain.
1. Disconnect the test leads from the meter. Voltage connections might
affect the hFE reading.
2. Plug a transistor into the hFE socket, being careful to insert the ECB
leads in their proper holes.
3. Set the function control to an hFE position (NPN or PNP). hFE appears
on the display.
4. After a short pause, the meter displays the actual hFE of the
transistor. This value ranges from 1 to 39,999.
Notes: Do not take the hFE reading as an absolute measurement, but rather
as an indication that the transistor is operating. The true gain
of a transistor depends on its operating current. This meter
applies 500 to 1000 microA to the emitter and collector and
measures the base current to calculate the base gain.
You cannot measure the hFE of a transistor that is connected in a
circuit.
You cannot measure the hFE of an FET or other non-bipolar
transistor.
Some power darlington transistors contain internal base-to-emitter
resistors. Because the meter uses two current readings to
calculate hFE, any internal transistor resistance causes
undependable readings.
High-voltage junctions in power transistors prevent correct
readings. Also, the larger leads of the power transistor can
damage the test socket. Do not try to determine the hFE for power
transistors with this meter.
The meter displays a default hFE reading when you have not
connected a transistor but are in the hFE mode. The bar graph
reading is not stable - it ranges up and down while the display
maintains a running average of the random readings.
hFE is affected by temperature. Try not to warm the transistor
with your hand when you install the device in the socket. If the
hFE reading is not stable when you first measure it, let the
transistor's temperature stabilize first. Then try again.
Some transistors designed to operate at high frequencies show a
small amount of reverse gain (reverse beta).
To be sure that you are not reading a reverse hFE, check the
suspected low reading by reversing the E and C leads in the
socket. Use the higher reading of the two.
Caution: The transistor socket is NOT protected against over-voltage.
You can damage the meter and void your warranty if you build and
use external leads for the transistor socket.
MEASURING CAPACITANCE
Before you measure capacitance, fully discharge the capacitors. Follow
these steps to measure capacitance.
1. Set the function control to one of the F ranges. The selected range
appears on the display.
2. Plug the red test lead into the + jack, and plug the black test lead
into the -COM jack.
3. If the capacitor is the electrolytic type, attach the red test probe
to the capacitor's positive side, and attach the black test probe to
the capacitor's negative side. Or, plug the capacitor into the
- ohm/diode/capacitance + socket. (Observe the polarity for
electrolytic capacitors.)
4. Read the measured value on the display.
Notes: An electrolytic capacitor's measured capacitance changes depending
upon the voltage applied to the capacitor. Because this meter
cannot use high voltages to set the electrolyte, it cannot measure
the absolute capacitance value.
The lowest capacitance ranges have an internal capacitance that is
the actual input capacitance of the instrument. If you want to
make measurements at very low ranges, subtract the internal
capacitance from the measurements. The internal capacitance is
the displayed measurement when neither probe is connected to a
component.
USING THE HOLD FUNCTION
The hold function lets you freeze the measurement reading on the meter's
display. This function is useful when there are many voltage changes and
you need a snapshot of the voltage.
To use the hold function, connect the test probes to the component or
circuit you want to measure. When you want the meter to hold the reading,
press DATA HOLD. The reading locks on the display and HOLD appears. In
the hold mode, the meter cannot take any more measurements. To clear the
hold reading and allow the meter to resume normal operation, press DATA
HOLD again.
USING THE BAR GRAPH
In addition to the numeric display, the meter displays all measurements on
a bar graph at the bottom of the display. The bar graph is updated more
quickly than the digital display, and gives a better indication of levels
and trends for varying measurements. The bar graph has 41 marks. The
first mark is always on, and indicates 0. Each additional mark represents
100 digits.
For example, if the displayed value is 1.853, 19 marks appear on the bar
graph.
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