Digital Multimeter (220-0182) Operation Faxback Doc. # 7586
UNDERSTANDING PHANTOM READINGS
In some DC and AC voltage ranges, when the probes are not connected to any
circuit, the display might show a "phantom" reading. This is normal. The
meter's high input sensitivity produces a wandering effect. When you
connect the probes to a circuit, accurate reading appears.
MEASURING HIGH-VOLTAGE CIRCUITS
When you use the meter to check a high-voltage circuit, do not try to
position both probes at once. Instead, clamp one probe to the neutral
or ground lead of the circuit (usually a bare, green, or white lead in
AC wiring circuits) using insulated Slip-On Alligator Clips (Cat. No.
270-354). Then probe for voltages with the other probe. This helps
prevents you from accidentally touching a hot wire, because you need to
concentrate on only one test probe.
Warning: Never clamp onto a hot wire, (usually red, black, or blue in
AC wiring circuits). If you clamp onto a hot wire and touch
the other probe, you could receive a shock.
OVERRANGE INDICATION
The following display appears when the measurement exceeds the meter's
range. If you are measuring volts or amps, disconnect the meter from
the circuit you are measuring or change the meter's measuring range.
AC/DC VOLTAGE MEASUREMENT
WARNING: DO NOT TRY TO MEASURE A VOLTAGE GREATER THAN 1000 VOLTS DC OR
750 VOLTS AC. YOU MIGHT DAMAGE YOUR METER AND EXPOSE YOURSELF
TO A SEVERE SHOCK HAZARD.
Note: All the figures on the display blink when more than the maximum
voltage (DC 1000/AC 750 VOLTS) is supplied. If this happens,
DISCONNECT THE PROBES IMMEDIATELY.
Follow these steps to measure AC/DC Voltage:
1. Rotate the function selector to the desired ACV/DCV position.
Select the range as required for the voltage level to be measured.
If you do not know the voltage level, start with the range switch set
to the highest voltage position and reduce the setting as needed to
get a reading.
2. Plug the black probe into the meter's COM terminal and the red probe
into the meter's V-ohms terminal.
3. Connect the probes to the AC/DC voltage source you want to measure.
The voltage appears on the display.
Notes: If polarity is negative, a "-" appears on the left of display.
For the most accurate measurement, select the lowest voltage range
possible without getting an overload reading.
Measuring an AC Voltage on a DC Bias
To measure an AC voltage superimposed on a DC voltage source bias, follow
the steps for measuring AC voltage.
Caution: 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
intended for commercial or industrial use. If you want to measure 3-
phase, line-to-line voltages, please note the following.
Warning: Because of the dangers inherent in measuring three-phase
circuits, we strongly recommend that you do not use this meter
for such applications.
If you choose to make the measurements, use extreme care. The actual
voltage can be greater than the circuit's rated voltage (line-to-
ground).
To determine the line-to-ground voltage, multiply the rated line-to-
ground voltage by 1.732.
For example, if the rated voltage is 462 volts, the line-to-line voltage
is.
462 Volts X 1.732=800 Volts
This voltage exceeds the meter's range and you should not connect the
meter to this circuit. See "Measuring High-Voltage Circuits".
Measuring AC/DC CURRENT
Warnings: DO NOT APPLY VOLTAGE DIRECTLY ACROSS TERMINALS. YOU MUST
CONNECT THE METER IN SERIES WITH THE CIRCUIT.
THE 20A TERMINAL IS NOT FUSED. A SEVERE FIRE HAZARD AND SHORT
CIRCUIT DANGER EXISTS IF YOU APPLY A VOLTAGE WITH HIGH-CURRENT
CAPABILITY TO THIS TERMINAL. THE METER CAN BE DESTROYED UNDER
SUCH CONDITIONS.
To measure current, break the circuit and connect the probes to two
circuit connection points. Never connect the probes across a voltage
source in parallel. Doing so can blow the fuse or damage the circuit
under test.
Note: The maximum input current is 2A or 20A depending on the terminal
used. In the 2A range, excessive current blows the fuse, which you
must replace. The 20A range is NOT protected by the fuse-
excessive current can destroy the meter.
1. Rotate the function selector to the desired AC A or DC A range.
If you do not know the current level, set it to the highest position
and reduce the setting as needed to get a reading.
2. Plug the back probe into your meter's COM terminal, and the red probe
into your meter's A or 20A terminal.
3. Remove power from the circuit under test and then break the circuit
at the appropriate point.
4. Connect the probes in series with the circuit.
5. Apply power and read the current.
Your meter displays the current value.
Note: If you set the meter for DC current, - appears or disappears to
indicate the polarity of the measured current.
MEASURING CAPACITANCE
Follow these steps to measure normal capacitance:
Discharge each capacitor before testing by shorting its leads
together. Use caution when handling some capacitors, as they can be
charged with considerable electricity.
Caution: If you attempt to measure the capacitance of a charged
capacitor, you might damage your meter.
2. Rotate the function selector to the desired CAP range. If you do not
know the approximate capacitance value, set the range to the
highest position and reduce the setting as required to get a valid
reading. The display shows a residual value. To obtain a 000
display, press LOGIC REL.
3. Insert the discharged capacitor into the CAP + and - clips connectors.
Your meter displays the capacitance value.
Note: For polarized capacitors, be sure to insert the negative lead in
the lead in the - clip.
MEASURING RESISTANCE
Warning: NEVER CONNECT THE TEST PROBES TO A SOURCE OF VOLTAGE WHEN YOU
HAVE SELECTED THE OHMS FUNCTION AND PLUGGED THE PROBES INTO THE
V-OHMS TERMINAL.
BE SURE THAT THE CIRCUIT UNDER TEST HAS ALL POWER REMOVED AND
THAT ANY ASSOCIATED CAPACITORS ARE FULLY DISCHARGED BEFORE YOU
MAKE A RESISTANCE MEASUREMENT.
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 in-circuit resistance, be sure the circuit
under test has all power removed (all capacitors are fully discharged).
1. Plug the black probe into your meter's COM terminal and the red probe
into your meter's V - ohms terminal.
2. Rotate the function selector to the desired ohm range.
3. Connect the probes to the device you want to measure.
Your meter displays the resistance value.
Notes: If the measured resistance value exceeds the maximum value of the
range selected, OL displays to indicate overload and the bar graph
flashes. Select a higher range. In this mode, the beeper does
not sound.
When you short the test probes in the 200ohms range, your meter
displays a small value (no more than 0.3 ohms). This value is
due to your meter's internal resistance measurements. To obtain
000 display at this time, press LOGIC REL on the meter while
shorting the test leads.
For resistance of approximately 1 Megohm and above, the display
might take a few seconds to stabilize. This is normal for high
resistance readings.
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. Plug the black probe into your meter's COM terminal and the red probe
into your meter's V-ohms terminal.
2. Rotate function selector to the >|music note.
3. Connect the probes to the diode you want to check and note the meter
reading.
If the display shows a value, for example 0.2 for germanium diode or
0.5 for a silicon diode, reverse the diode. If the meter indicates
an overrange, the diode is good. The displayed number is the diode's
actual forward voltage (up to 2.5 volts).
If the display indicates an overrange condition, reverse the polarity
of the connection. If the display shows a value, the device is good.
The displayed value is the component's actual forward voltage (up to 2.5
volts). If the display still indicates an overrange condition, the
device is open.
If the display shows a value both before and after you reverse the
polarity, the device is shorted or the meter's 1/18 amp fuse is blown.
When you connect the diode to the meter and the meter displays the
device's forward voltage, the red test probe or >|music notes socket is
connected to the diode's anode, and the black probe or >|music notes
socket is connected to the diode's cathode.
This meter supplies enough forward voltage to light most LEDs. However,
if the LED's forward voltage is greater than 2.5 volts, the meter
incorrectly indicates that the device is open.
The bar graph shows a maximum reading of 24, even during an overrange.
CHECKING CONTINUITY
Follow these steps to check a circuit's continuity:
1. Rotate the function selector to >|music note.
2. Plug the black probe into your meter's COM terminal and the red probe
into your meter's V-ohms terminal.
3. Remove power from the circuit.
Warning: Never perform a continuity measurement on a circuit that
has power connected.
4. Connect the probes to the circuit.
Note: The buzzer sounds if the measured resistance is below 30 ohms.
CHECKING TRANSISTORS
Follow these steps to determine a transistor's base gain:
1. Rotate the function selector to the hFE position.
2. Insert the transistor you want to measure into the appropriate
transistor socket. Your meter displays the transistor's hFE
value.
Notes: Insert the base, collector, and emitter pins in the correct
sockets, as marked.
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.
Even though the meter turns off the test probes during the hFE
measurement, a voltage connection might affect the hFE reading.
Do not connect the test probes to a voltage source during this
measurement.
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 type, pin-out, or hFE for power
transistors with this meter.
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.
Warning: The transistor socket is not protected against overload. You
can damage the meter and void your warranty if you build and
use external leads for the transistor socket.
MEASURING FREQUENCY
WARNING: IF YOU TRY TO MEASURE THE FREQUENCY OF A SIGNAL THAT EXCEEDS 250
VOLTS AC RMS, YOU MIGHT DAMAGE YOUR METER AND EXPOSE YOURSELF
TO SEVERE SHOCK HAZARD.
Follow these steps to measure the frequency of a signal:
1. Rotate the function selector to the FREQ range.
2. Plug the black probe into your meter's COM terminal and the red probe
into your meter's V-ohms terminal.
3. Connect the probe to the frequency source.
Notes: When the test probes are connected to an AC outlet, do not turn
the function selector switch to another range. It may damage
the internal components, or you.
Overload Protection: 250V DC/AC RMS
LOGIC TEST
The logic function lets you easily check digital circuits to determine
the logic state of different parts of the circuit. Rather than display an
absolute voltage, this function displays HI, LO, or --- to indicate logic
high, logic low, or undetermined, respectively.
Follow these steps to perform a logic test:
1. Rotate the function selector to the logic range.
rdy appears on the display.
2. Plug the black probe into your meter's COM terminal and the red probe
into your meter's V-ohms terminal.
3. Connect the black probe to the ground point (GND) of the test circuit
and the red probe to the supplying voltage point (V+). While keeping
the test probes firmly connected to each point, press LOGIC REL.
4. While keeping a connection between the black probe and the circuit's
GND point, move the red probe to the other desired points. The meter
immediately displays one of the 3 modes, as follows:
If value exceeds 70% of the stored (V+) value, HI (HIGH) appears.
If value falls below 30% of the stored (V+) value, Lo (LOW) appears.
If value is between 30% and 70%, the --- segment appears.
Notes: In this mode, the Data-Hold and Max/Min-Hold functions do not
work.
The supplying voltage from 0.5V up to 19.9V is limited for testing
logic.
USING THE MAX/MIN MEMORY FUNCTION
The MAX/MIN button holds a recorded value on the display, records the
maximum value currently measured, and/or records the minimum value
currently measured. Follow these steps to store the readings:
1. Press MAX/MIN. The meter displays MAX and displays the highest
measured reading. The meter updates the display as the reading
changes.
Even though the meter only displays MAX, it stores both the maximum
and minimum readings.
2. To display the minimum measured reading, press MAX/MIN again. The
meter displays MIN and the lowest measured reading. The meter updates
the display as the reading changes.
Even though the meter only displays MIN, it stores both the minimum
and maximum readings.
Notes: You cannot use the MAX/MIN mode and the relative mode at the same
time. If you select the relative mode, the MAX/MIN function turns
off. If the relative mode is already active, the meter ignores
the MAX/MIN key.
The meter exits MAX/MIN mode if you try to measure a value that
is outside the currently set range or if you manually change the
range.
USING DATA HOLD
The data hold function lets you hold the current reading on the meter's
display.
During any reading, press D-HOLD to prevent changes in the measured value
from updating the display. The meter displays HOLD. Press D-HOLD again
to resume normal operation.
USING THE RELATIVE FUNCTION
The relative feature lets you set a reference measurement and measure
additional values relative to the reference. For example, if you set
the reference at 100 ohms, the meter displays a 123 ohm resistor at 23
ohms, and displays a 75 ohms resistor as -25 ohms.
Follow these steps to set a reference:
1. Make a reference measurement.
2. While you measure the reference value, hold down LOGIC REL for about
2 seconds. The meter beeps. After 2 seconds, the meter displays REL
and sets the reading to 000.
The meter displays additional measurements relative to the reference
value.
The meter displays additional measurements relative to the reference
value.
Note: You cannot use the MAX/MIN mode and relative mode at the same time.
USING THE METER WITH A COMPUTER
INTERFACING THE METER WITH A COMPUTER
Follow these steps to interface the meter with a computer:
1. Connect the RS-232C cable between the meter's and computer's serial
ports.
2. Turn on the meter.
USING THE SUPPLIED SOFTWARE
The supplied software runs on PC-compatible computers only.
Follow these steps to use the supplied software:
1. Place the diskette in the drive. Copy the files from the diskette
to the computer's hard drive or make a back-up copy of the diskette to
use.
2. Type Enter.
Note: The software automatically defaults to color monitors.
3. To stop execution or to escape from a device I/O error status, press
CTRL+BREAK on the computer at the same time.
Notes: You must turn off the meter's COM switch when transmitting data
to the computer.
Do not activate the meter's COM function and the computer's
transmission commands at the same time.
To release the COM function, turn the range switch or press COM.
COM disappears.
HINTS FOR WRITING YOUR OWN SOFTWARE
If you write you own program, you must include these steps:
1. The host computer must give the meter the D command to activate data
transmission.
2. The host computer must give the meter the C Memory-Clear command to
clear memories on the meter.
3. The host computer must give the meter the M Memory-Call command to
transmit the memories on the meter to the software.
Data Format
The data format consists of a frame of 14 bytes. The frames are set as
follows:
BYTE) 1 2 3 4 5 6 7 8 9 A B C D E
Ex. 1) DC-1. 9 9 9 9 V CR
Ex. 2) 1. 9 9 9 9 M o h m CR
The following program is an example of a BASIC program that gets a single
reading from the meter:
10 OPEN "COM 1: 1200, N, 7, 2, RS, CS, DS, CD" AS #2
20 A$="D"
30 PRINT # 2, A$
40 IN$=INPUT$(14, #2)
50 PRINT IN$
60 CLOSE #2
70 END
Communication parameters
Transmission rate: 1200 baud
Character coding : 7-bit ASCII
Parity : NONE
Stop Bits : 2
REPLACING THE FUSE
WARNING: TO AVOID ELECTRIC SHOCK, DISCONNECT THE TEST PROBES BEFORE
REMOVING THE BATTERY OR THE FUSE. REPLACE ONLY WITH THE SAME
TYPE OF BATTERY OR FUSE. DO NOT REMOVE THE TOP COVER. SERVICE
SHOULD BE PERFORMED ONLY BY QUALIFIED PERSONNEL.
CAUTION: FOR CONTINUED PROTECTION AGAINST FIRE OR OTHER HAZARD, REPLACE
ONLY WITH A 2A 250 V FUSE.
Follow these steps to replace the fuse:
1. Set power to OFF and disconnect the test probes.
2. Remove the back cover by unscrewing the four screws and pulling off
the meter's cover.
3. Remove the blown fuse.
4. Install the new fuse in the fuse compartment.
5. Replace the back cover and secure it with the screws.
WARNING: DO NOT OPERATE YOUR METER UNTIL THE BACK COVER IS IN PLACE AND
FULLY CLOSED.
(lb/all-9/19/94)