Radio Shack 22-174A User manual

Cat. No.22-174A
OWNER'S MANUAL
Please read before using this equipment.
Radpfhaek@

FEATURES
This Radio Shack True RMS Multimeter is a portable,
92ls-digit meter ideal for field, lab, shop, berich, anci
home use. The meter uses the latest lC and display
technology to achieve the lowest possible component
count, and the true RMS converter is built into d single
multimeter chip. These features make the meter rugg-
ed .and.gqsy io use and ensure reliability, accuralc!,
and stability. Your meter also includes the fbllowing b+
tures.
LCD Bar Graph Display - makes nulls, peaks, and tends
more apparent.
Translstor-Check Function - measures the gain (hre) of
small-signal, bipolar transistors and identifies pinout and type.
;fllly AuteRanglng - makes your meter easier and safer to
-use by letting you concentrate on the probes, and also lets you
manually set the range lor situations where you know what val-
ues to expect.
Volts or dBm Voltage Display - lets you select the unil of
measure that suits your application.
Dat+Hold Functon - freezes the display so you can view
the reading even after you disconnect the leads.
Condnulty Functlon - quickly checks the continuity of wires
or traces.
True RMS Operation - gives a more accurate reading for
non-sine wave AC measurements.
Effective Overload and Translent Protectlon - covers all
ranges except the DC/AC 10A range.
@ 199a Tandy Corporation,
All Bights Rceerved.
Radio Shack io a reglatered trEdomark
' uaed by Tandy Corporatlon.
2
Full Auto-Polarity Operation - protects your meter and
gives valid measurements when you connect the leads in rs.
verse polarity.
Frequency Counter - measures frequencies up to 2 MHz.
Diod+Check Function - safely checks semiconductors for
open, shorted, or normal junctions.
Low-Battery lndication - shows you when battery power is
low by displaying a low-battery indicator.
Folding Wire Stand - lets you use the meter on a bench top.
UL Listed - passes the stringent tests required by Undenrtrrii-
ers Laboratories for safety.
Built-ln Temperature Function - measures temperatures
tro1r - 58"F to 302"F (- 50'C to 150'C) and gives the readilFp
in Fahrenheit (F) or Celsius (C). 'l')'
Cautions:
o Completely read this manual belore you use the meter.
r ll you are not familiar with meters and testing procedures,
we suggest that you obtain and read a book about the sub
ject, such as "Using Your Metef'(Radio Shack Cat. No.62-
2039).

CONTENTS
A Word About Safety ................... 5
What Does "True RMS" Mean? ...."................... Z
Specifications ........ g
Special PanelMarkings .................. ................. 14
Preparing for Operation ............. 15
lnstalling Batteries ................. 15
Using Test Leads ........... ....... 16
Making Measurements ................. ................... 17
Turning On the Meter ........... ....................... 17
Understanding Phantom Readings ............ 1T
Overrange lndication ............. jZ
Measuring DC Voltage ......... 19
Measuring AC Voltage ......... 20
Measuring an AC Voltage on a DC Bias ......................-... 21
Measuring 3-Phase AC Voltages _-...-----....- 22
Measuring AC/DC Current ......-......-_......... 23
Measuring Resistance ......... 26
Checking Continuity ........ 29
Checking Diodes ............-...... gO
Checking Transistors ..-.-...... 92
Measuring Frequency .......... 35
Measuring Capacitance --..... 97
Using the Hold Function ....... 38
Using the Bar Graph ............. 39
Manually Selecting the Range ...".....--........ 39
Using the Beep Function ......-........... .......... 40
Using the Temperature Function ................. 40
Maintenance ....... 42
Replacing the Fuses ............. 42
Caring lor the Meter ................... 44
Lg hSug taken every precaution in designing this meter to en_
sure that it is as safe as we can.mat<e'it. g"ui, safe op"i"fion
depends qn yqu, the operator. We ,ecommbnd you follow
these simple safety rules:
o Never.apply voltages to the meter that exceed the limits
$:'' ?Jffi ffi3'[3' !:il]"Jff lRy,ii:n,X5: l,?3fj
apply more than 500V DC or 500V Ril,ts A-C dtu;;;;i
input terminal and ground.
o Use extreme caution when you work with voltages above
40V. Atways disconnect power from tfrJ circuii t* t;
measuring before you connect test leads to tigh;tAJ
points.
o Never connect test leads to a source of voltagb when yofr
select. the diode, ohms,. continuity, crrrent -reasurement,
capacitance, or hre functions.
I Always discharge filter capacitors in the power supply of the
circuit under test before you attach test leads.
o flwqVs turn off the meter's power and disconnect the test
leads before you replace thebatteriei ;ril;;.
o Never.operate the meter unless the battery cover is in place
and fully closed.
. P::::"^lany AC/DC sets.have a potentiaily hol chassis,
?e_ sure rhe top of your workbench and the flo6r underneath
tr are made of non_conductive materials.
.f.fe rytJiryter is. fulty catibrated and tested. Under normat
!lp-,_no,lrtllr"r adjustment is necessary. tf the meter does re.
eurr€ adjrrs1llg, do not try to adjust.it yourself. Take it to your
nearesl Radio Shack store. Service Uy unautfrorizeA perso,nnet
voids the waranty.
A WORD ABOUT SAFETY

WARNING: USE EXTREME CAUTION lN USE OF THIS DE-
VICE. IMPROPER USE OF THIS DEVICE CAN RESULT IN
INJURY OR DEATH. FOLLOW ALL SAFEGUARDS SUG.
GESTED IN THE OWNER'S MANUAL IN ADDITION TO NOR-
MA! SAFEW PRECAUTIONS IN DEALING WITH ELECTRI-
CAL CIRCUITS. DO NOT USE THIS DEVICE IF YOU ARE
UNFAMILIAR WITH ELECTRICAL CIRCUITS AND TESTING
PROCEDURES.
NOT FOR COMMERCIALOR INDUSTRIAL USE.
WHAT DOES'TRUE RMS' MEAN?
RMS stands lor Root-Mean-Square. RMS is a standard
method for determiriing the effective value of a varying or alter-
nating voltage. The RMS value is the DC voltage that would
produce the same amount ol heat as the voltage you are
measuring, if you were to apply both voltages across identical
resistors.
The true RMS value is helpful when you need to measure an
AC voltage that is not a pure sine wave. Most meters uS€ oVOr.
ageresponding AC converters. These meters are calibrated
with pure sine waves. lf you measure a sine wave that does
not have harmonic distortion, the m.eter gives an accurate
reading. But, if the sine wave is not pure-there are distor-
tions within the waveform, or you measure triangle waves or
square waves - the average.responding meters display an in-.
',8
For example, a 2-volt peak-topeak, 500/o duty cycle square:
wave measures correctly as 1.000 VAC on this meter. An aver-
-age responding meter displays 1.111 VAC-an error of more
than 11 percentl,
The maximum frequ'ency your meter can accurately measure
is 5000 Hz lor AC voltrage and 1000 Hz lor AC current. The al-
lowable crest factor is 1:1 to 3:1. The crest factor is the ratio ol
the peak signal value divided by the RMS value. A 10% duty
cyole square wave with a peak voltage of 3 volts has an RMS
value ol about .95 volts. This gives a crest factor of 3.16 (3V/
.95V), and is outside this meter's range of accuracy.

SPECIFICATIONS
DC VOLTS
Accuracy is shown as o/o of full scale, plus the number of digits
between 5% of range and full scate (eicept on 1000 V scatej.
lnput lmpedance ..................... 1OM Ohms in parallelwith 2 pF
Normal Mode Rejection Ratio .. > 60 dB at 60 Hz
Response Time to Rated Accuracy ................ 2 Seconds Max.
Maximum lnput ............ . 1000VDC
AC VOLTS firue RMS Responding, AC Coupted)
Accuracy is shown as 7o of full scale, plus the number of digits
between 5% of range and full scale (except on Z50V scale).-
Ranges
(Maximum
Readinq)
Resolution Accuracy
1000 v1V + 20 V. t 2 Dioits
399.9 V100 mV !1o/o.+ 2 Dioits
39.99 V10 mV +1o/o.t2Dioits
3.999 V1mV t1o/o.t2Dioits
399.9 mV 100 uV t1..50/o. t 2 Dioits
Allowable Crest Factor Range . Ratio ol 1:1 tffi:.1
at Full Scale
dBm RANGES
lnput Range ..:..................
Maximum lnput Voltage .... 60 dBm, 1000 V peak
lnput lmpedance .............. 1 Ma in parallel with 2 pF
Ranges
(Maximum
Readino)
Resolution Accuracy
at 60Hz-lkHz Accuracy
at 30Hz-5kHz
750 V1V 30v.r3 45 V.1 5
399.9 V100 mV 3o/o. t 35%.15
39.99 V 10 mV 3o/o. t3 5o/o. !.5
3.999 V 1mV 3olo. t 35%.15
399.9 mV 100 pV 3o/o, + 3
Reading Resolution Accuracy at 60 Hz
>+54dBm 0.1 dBm t.7 dBm
+ 54 to -27 dBm 0.1 dBm t.4 dBm
<-27 dBm 1 dBm t 1.2 dBm

DC CURRENT
Range Jack Max.
Readino Rese
lution Accuracy
10A 104 9.99 A 10 mA t3.5%.i5Diaits
4A 10A 3.999 A 'I mA t5.5o/o. t 5 Dioits
400 mA 400 mA 399.9 mA 100 uA t2%.+2Diaits
40 mA 400 mA 39.99 mA 10 uA t 3.5olo. 12 Dioits
4000 uA 400 mA 3.999 mA 1 rrA + 2o/o.+ 2 Dioits
400 uA 400 mA 399.9 uA 100 nA + 2o/o.+ 2 Dioits
40 uA 400 mA 39.99 uA 10 nA + 2o/o,+ 2 Digits
4uA 400 mA 3.999 uA lnA +2olo,+2Digits
RESISTANCE
AC CURRENT (frue RMS Respondlng, DG Coupled
@ 1 kHz) Overload Protection ....... Fused - 500 V AC/DC on Ail R€Uges
ln-Circuit Voltage .... 0.4 Votts or Less (< 0.5V for 399.9 dfrns)
ResponseTirne " "',Jg*::iff:y$illa1nx,"::!33
CAPACITANCE
Maximum Allowable DC Level .. Less than Full Scale of Range
Allowable Crest Factor Range 1:1 to 3:1 at FullScale
10
Ranges
(Maximum
Readinql
Resolution Accuracy
19.9 MO r0 ko t2.5o/o. + 3 Dioits
3.999 Mc) lko X1o/o,X 3 Dioits
399.9 ko 100 c) X1o/o.t3 Dioits
39.99 kf) 10o t1o/o,t 3 Dioits
3.999 kO 1C) tlo/o.X 3 Dioits
399.9 O0.1 ot1.So/o.t3Dioits
Range Jack llax.
Reading Resolu- tion Accuracy
10.00 A 10A 9.99 A 10 mA 5.5olo, t 3
4.000 A 10A 3.999 A 1mA 7.5o/o, !3
400.0 mA 400 mA 399.9 mA 100 uA 3.57o, t 3
40.00 mA 400 mA 39.99 mA 10$ 6.59o. t 3
4.000 mA 400 mA 3.999 mA 1tlA 4Vo,+ 3
400.0 pA 400 mA 399.9 mA 100 nA 4o/o, + t
40.00 xA 4(D mA 39.99 pA 10 nA 4o/o, + 3
4.000 uA 4fi) mA 3.999 pA 1nA 4o/o, + 3
Ranges
(Maximum
Readinss)
Resolution Accuracy
399.9 rrF 100 nF t6%.t3Dioits
39.99 uF 10 nF t3o/o.t3 Dioits
3.999 uF 1nF t2o/o.!3 Dioits
399.9 nF 100 oF t2o/t.t3 Dioits
39.99 nF 10 pF t*/o.*3 Dioits
3.999 nF 1oF *3%.t 3 Dioits
11

FREQUENCY
Ranges
(Max. Readinosl Rerolutlon Accuracy
2.000 MHz 1 kHz t5o/o.t 5 Dioits
399.9 kHz 100 Hz +30/o.+l Dioit
39.99 kHz 10 Hz t3%.t1Dioit
3.999 kHz 1Hz t3o/o,tl Diqit
lnput Sensitivity ................ 500 mV p-p
lnput lmpedance .................... 1 Megohm in Parallelwith 50 pF
DIODE TEST
The diode test is performed by measuring the voltage drop
across the diode.
Nominal Current
Overrange ..:.................. > 2 VDC to Open Circuit
CONTINUITY TEST
The continuity test is a.resistance measurement perlormed in
the 399.$ohm range. Opencircuit conditions give an over-
range indication. Beeper operation is automatically enabled.
Continuity is defined if resistance is 50 ohms or less. The
beeper sounds within 150 milliseconds of the reading.
hre FUNCTION
Direct Reading of hrE from 0 to 39.99K
Emitter Current .... 0.5 mA (Approx.)
VCe ............................;....... Ranges from 1 to 3 Volts (Approx.)
12
GENE RAL SPECIFICATIONS
Temperature Function:
Total Range .. - Sg. to 302.F (- S0" to 150"C)
32o lo 212"F (0' to 100'C) Accuracy I 3.6"F (2"C)
Repeatability Per Probe + 1.8.F (1.C)
Sensor Type ............ ..... Thermistor (Supplied)
Normal Sensor Resistance ................... 10 kO
Response Time ............ .. 5 Seconds (Typical)
(Depends on Contact Quality and Ambient Temperalure)
Operating Temperature 32. ls 12ZaF (0" to 50"C)
Storage Temperature:
Without Batteries - 20" to 158.F (- 29. to 7ffiC)
With Batteries ....................... -2C lo 122"F (- ZSfo Sd6b)
Relative Humidity:
On resistance measurements greater than i MO and
400 mVDC, 400 nF capacitance ranges, relative humidity
is up to 80% @ 32. to,95.F (0" to 35"C)
All Other Ranges: Up to 90% @ 32. to gs"F (0" to 35.C)
Up to 70% @ 95'to 122.F (3S" to 50"C)
Maximum Common-Mode Voltage ......... SOO VDC or peak AC
Dimensions 81/2x 43/a x 211.4a lnches
Weight 1tb7 oz (Approx.)
Power Requirements 6 MBatteries
Battery Life (Alkaline) ........... 500 Hours Minimum
Low-Battery lndication 3.gO V r 0.1 V
Battery Measurement Frequency ........ 1 Per Minute, Minimum
Standards ETL, UL, FCC
13

SPECIAL PANEL MARKINGS PREPARING FOR OPERATION
Your meter requires 6 AA batteries for power. We recommend
. alkaline batteries, such as Radio Shack's Cat. No. 2g-552.
WARNING: TO AVOID ELECTRIC SHOCK, DTSCONNECT
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.
E"*
EA'ffi
FI
=
Open the battery/fuse
compartment cover by
pressing down on the
cover's arrow and sliding
the cover in the direction
of the arrow.
lnstall the batteries, as
indicated by the polarity
marks (+ and -) and
illuskation inside the
battery compartment.
4. Replace the compartmenl
cover.
INSTALLING BATTERIES
We have placed the following special markings on the meter to
remind you of important safety precautions.
10A
1OAMAX,,^.
(o)
UNFUSED\:Z
The maximum current you can
measure is 10 amps DC/AC. This
terminal is NOT fuse protected.
ry
Be extra careful when you measure
for high voltage. Do not touch the
terminals or test leads.
1000v Dc
750V DC
400mA
MAX
The maximum voltage that you can
measure is 1000 volts DC, 750 volts
AC, or 400 mA.
-coM
n@ Do not connect the meter's - cOM'
terminal to a source of voltage
greater than 500 volts with reference
to ground.
Be sure to read all instructions
included with this meter.
I
L
t14
I
15

WARNING: DO NOT OPERATE THE METER
CORRECTLY INSTALL THE BATTERIES AND
BATTERY COMPARTMENT COVER.
When the batteries become
weak, BATT appears on the
left side of the display. Replace
all batteries. Bemove the bat-
teries when you will not use the
meter for a week or more.
Never leave lireak 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 lor 1200 volts. You can buy replacement leads
(Cat. No. 278-7041from your local Radio Shack store.
Cautions:
o Although these test leads are rated for 1200 volts, the maxi-
mum rating of this meter is 1000 volts DC and 750 volts AC.
Do not try to measure any voltage that exceeds these rat-
ings. Use extreme caution when you use high-voltage
ranges.
o 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 OwOFF to ON.
UNTIL YOU
CLOSE THE
UNDERSTANDING PHANTOM READINGS
lf 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 inpit
sensitivity and is normatlor most highquality, high-impedSe
meters. When you connect the probes to a circuit, a real meas-
urement appears.
OVERRANGE INDICATTON
The following display appears when the measurement exceeds
the selected range. lf you are measuring volts or amps, discon-
nect the meter from the circuit you are measuring'or change
the meter's measuring range. See,,Notes" on page t8.
c=l
d'"
- l*'!*ri[*'itooo0oooo0oooo0oooo0o'.* >
llnnnnIonnnInnnnIonnolnnr
05101520
16 17

Notes:
o The meter displays the overrange indication or 0 if it blows
a fuse while measuring current.
o lf 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 currenl, the signal has both an AC and DC compo-
nent. lf 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 llows through the
shunt resistance. Too much DC current overpowers the AC
component. lf 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 pF or larger capacitor.
MEASURING DC VOLTAGE
WARNING: DO NOT TRY TO MEASURE A VOLTAGE
GREATER THAN 1OOO 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
Y. 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 i
terminal.
rM -cou * &
--"@flQ^@w
-- ------t T
Black Red
3. Connect the black test
probe to the COMMON
point for the voltage to be
measured. Connect the
red test probe to the volt-
age you want to measure.
When you measure DC voltages, the minus sign (-) appears if
you connect the black test probe to a point in the circuit that
has a higher voltage potential than the point where you con-
nect the red test probe.
Note: The meter does not measure DC using dBm. lf you try to
select dBm, the meter switches to AC measurements.
18 19

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.
Hint When you use the meter to
probe for a voltage in a high-volt-
age circuit, do not try to position
both probes at the same time. ln-
stead, clamp the black lead to
the neutral or ground circuit lead
(usually a bare, green, or white
lead) using an insulated SlipOn
Alligator Clip (Cat. No. 270€54)
and probe for voltages with the
red lead.
You need to concentrate on only
one test probe, so place vour
free hand in your baci< pock6t or Blacl(
behind your back. This helps pre'
vent you from accidentally touch-
ing a hotwire (usually red, black,
or blue) with the hand.
WARNING: lF YOU CLAMP ON TO A HOT WIRE AND
TOUCH A CONNECTED TEST PROBES AT THE SAME, YOU
COULD RECEIVE AN ELECTRIC SHOCK.
MEASURING AN AC VOLTAGE ON A DC BIAS
This meter contains a DG blocking capacitor, which lets AC
voltrage pass through it, but blocks DC voltages. lf 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 19 and 20.
Nsutral or
Ground Lead
Alllgator
Cllp
1. Select AC volts by rotati4g
the lunction control to I.
v 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.
lo^ -@N, * 4
J"@fl9^qPtr
F lt
Black Red
3. Connecl the probes to the
voltage you will measure.
4. To change the display to
dBm, press rtB. The
display shows the reading
in dBm, and dBn
appears. To change the
reading back to volts,
press dB again.
trc .i &ro ur^
I .Eruc? J le
,Nu'
5E-@
20 21

I
4
:l
I
il
.i
i{
Warning: NEVER TRY TO MEASURE AN AC VOTTAGE
THAT IS RIDING ON A DC VOLTAGE LEVEL WHERE THE
PEAK AC VOLTAGE EXCEEDS 1OOOV WITH RESPECT TO
EARTH GROUND.
MEASURING SPHASE AC VOLTAGES
We designed this meter to measure household AC voltage. lt is
not for commercial or industdd use. lf you want to measure 3-
phase, lin+'to-line voltages, please note the following:
e Because of the dangers inherent when you measure three.
phase circuits, we strongly recommend you do not use this
meter for such applications.
o Do not exceed the maximum RMS AC rating (750 VAC).
o lf 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 lineto-line voltage, measure between the circuit
and a known ground point. Then multiply the result by 1.732.
For gxample, 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 haz-
ard and damage the meter.
22
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 volt-
age 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 IN-
PUT TERMINALS WHILE IN THE CURRENT MODE. YOU
MUST CONNECT THE METER IN SERIES WITH THE
ctRcurT.
THE 1OA INPUT TERMINAL IS NOT FUSED. A SEVERE
FIRE HMARD AND SHORT CIRCUIT DANGER EXIST IF
YOU APPLY A VOUTAGE WITH HIGH CURRENT CAPA-
BILITIES TO THIS TERMINAL. YOU ALSO COULME-
STROYTHE METER.
23
Set the function controlto
A or A . nA appears on
the display.
2. Set the current switch for
the desired current range.
Note: To measure a
current level that exceeds
0.4 amps, you must use
the 10A input.

3. Remove power from the
circuit under test. Then
break the circuit at the
appropriate polnt.
Connect the probes in
series with the circuit.
Test Unlt
Sorles Connoctlon
5. Apply power to the circuit.
\
f
lf the current is less than the maximum shown for the input
jack selected, the meter might down-range for a higher resolu-
tion reading. For example, if your measure a 3500 pA current
a.n! the curent changes to 350 pA, the meter automatically
shifts to the 400.0 pA range if the meter is in the auto mode.
Notes:
lf you set the meter for DC current, the minus (-) sign ap-
pears or disappears to the left of the bargraph to sho^/ the
polarity of the measured current.
The 400 mA and the 4000 pA ranges are fuse-protected.
The 10A range is not fuse-protected.
The meter displays the overrange indication or 0 il it blows
a fuse while measuring current.
lf the meter displays the overrange indication wnen"$ou
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
riple currenl, the signal has both an AC and DC compo-
nent. lf 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. lf you need to measure the AC component of a
DC signal, we suggest you use a highquality capacitor to
block the DC component. For normal AC line frequencies,
we suggest you use a .47 pF or larger capacitor rated lor
the vottage involved (500 volts or greater).
l.
I
24 25

MEASURING RESISTANCE
WARNING: BE SURE THE CIRCUIT UNDER TEST HAS ALL
POWER REMOVED AND ANY ASSOCIATED CAPACITORS
ARE FULLY DISCHARGED BEFORE YOU MAKE A RESIS-
TANCE MEASUREMENT.
The resistance measuring circuit compares the voltage gained
through a known resistance (internal) with the voltage oevel-
oped across lhe unknown resistance. So, when you check in-
circuit resistance, be sure the circuit under test has all power
removed (all capacitors are lully discharged).
As with the voltage range, use the measuring unit displalqto
determine the current resistance range. lf only e appdais
on the display, the values of the measurements are in
ohms. lf K and Q appear , the meter is measuring kilohms
(the reading x 1000). lf M and e appear, the meter is mea-
suring megohms (the reading x 1,000,000).
The meter has a fuse and a special circuit that protects the
lesisJance ranges from over-voltage (voltages greater than
5 volts). lf you blow the meter's fuse, the meter does not op
erate correctly in the ohms mode. Check the fuse if the me.
ter displays 0 for all resistance measurements, or if it dis-
plays other unusual readings.
3. Connect the probes
across the circuit to be
measured, or plug the
resistor under test into the
oHMS/DtoDE/cAp sockel.
lf the resistance is greater
than 1 megohm, the
display takes a few
seconds to stabilize. This
is normalfor high-
resistance measurements.
\*7
Reslstor
l+ o {F
- [cf:- c-] +
\CIMY
DtoDE,/oHys/clp
Notes:
Set the function control to
Q . O appears on the
display. lf there is no
resistance connected to
the meter, the meter sets
itself to the highest
measurement range if the
meter is in the auto mode.
When the display shows
u Q, the overrange
indication also appears.
2. Plug the red test lead into
the + jack and the black
test lead into the -COM
jack.
Black Red
26 27

When you touch the ends of the test probes together, the
meter selects the 400-ohm scale and displays a small
value. This value is the resistance of the test leads. Note
this value and subtract it lrom the measured value when
you measure a very small resistance.
When you measure resistance greater than 400 kQ, skin re'
sistance affects the reading. Use the DIoDE/oHMS/CAP
socket to measure resistors, il possible. lf you must hold the
resistor and use the leads, be careful not to touch both
probes while you take a measurement.
Ghecking Gontinuity
Your meter has a built-in audible continuity function. Follow
these steps to check a circuit's continuity.
Notes:
lf the circuit's resistance is less than or equal to 50 ohms,
the buzzer sounds. lf the resistance is greater than 50
ohms, but less than 400 ohms, the meter displays the cir-
cuit's resistance and the buzzer does not sound. The meter
shows an overrange condition if the resistance is 400 ohms
or greater.
There is no auto-ranging function in the continuity-check
mode.
1. Set the function control to
"rD . cour and Cl 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 lhe
circuit you want to test.
28 29

CHECKING DIODES
This lunction leb you check diodes and other semiconductors
for opens and shorts. lt also lets you determine the forward
voltage for diodes. You can use this function when you need to
match diodes.
Reverse the probes or
reverse the component in
the socket, and note the
second reading. lf one
value is normal and the
other is overrange, the
component is good. lf
both values are over-
range, the component is
open. lf both values are
very small or zero, the
component is shorted.
Notes:
The value indicated by the bar display during the clig$e
check function is the fonrard voltrage (approX.2.5 V max.).
When the diode is reverse biased, the display shows the
normal ovenange indication, but the bargraph shows 25.
This reading is the actual open+ircuit (reverse biased) volt-
age. (2.45 volts appears as 25 on the bargraph.)
lf the display shows a low voltage reading, the red test
probe is allhe anode of the diode and the black probe is at
lhe cathode (banded side) of the diode. This condition is
called the foruard biasd condition.
lf the diode is in a forward biased condition and if you use
the DloDgoHMgcAP to test the diode, the anode is at the +
side ol the socket and the cathode is at the banded (-) side.
This meter supplies enough fonrvard voltrage to light most
LEDs. This lets you determine if an LED is good and which
lead is the cathode.
1. Set the function control to
# -or appearson
the display.
2. Plug the red tgst lead into
the + jack and the black
test lead into the -COM
jack.
ro -cou * 4
*"@fl9^Qtr
----I l l
Black Red
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 DloDgoHMg
CAP test socket and note
the display.
DroDE/OHMS/CAP
30 31

Follow these steps to determine a transistor's pinout, type, and
base gain.
1. Disconnect the test leads
from the meter. Voltage
connections might affect
the hre reading. ++
2. Plug a transistor into the
hFE socket.
3. Set the function control to
hFE. hrE appears on the
display.
The meter displays the
transistor type (upu or
PnP) for several seconds.
Then the meter displays
the transistor's pinout.
The three letters it
displays correspond to the
three terminals of the nre
socket. For example, if
the meter displays uuc,
the far left lead is the
emitter, the middle lead is
the base, and the far right
lead is the collector. aro16a
Pr^P
EEI k
Ebt
Notes:
o Do not take the hre 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 cur-
rent. This meter applies 500 to 1000 pA to the emitter and
collector and measures the base current to calculate the
base gain.
o You cannot measure the hre of a transistor that is con-
nected in a circuit.
You cannot measure the hre of an FET or other non-bipolar
transistor.
Some power darlington transistors contain internal base-to-
emitter resistors. Because the meter uses two current read-
ings to calculate hre, any internal transistor resistance
causes undependable readings.
rF
After another short pause,
the meter displays the
actual hre of the
transistor. This value
ranges from 1 to 39,999.
The meter continuously
displays the hre, even if
you plug another
transistor into the socket.
To force the meter to re-
examine the transistor
type and pinout, press
TEST after you plug in the
new transistor.
fq"gT
32 33

o 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, and hre for power transistors with this meter.
o The meter displays a delault junction type and pinout if you
press hre when you have not connected a transistor. The
meter defaults to PnP and CEb with the hrE measurement
given as a very large value or overflow condition. The bar
graph reading is not stable - it ranges up and down while
the display maintains a running average of the random
readings.
o hre is affected by temperature. Try not to warm the transis-
tor with your hand when you install the device in the socket.
lf the hre reading is not stable when you first measure it, let
the transistor's temperatu re stabilize.
. Some transistors designed to operate at high frequencies
show a small amount of reverse gain (reverse beta). This
can make your meter display an inconect transistor type
and pinout.
To be sure you have the correct pinout and transistor gpe,
check all transistors twice - once with the transistor's flat
side facing you and once with the flat side facing away from
you. The reading that indicates the highest gain is the cor-
rect reading.
Gaution: The transistor socket is NOT protected agains! over-
voltage. You can damage the meter and void your warranty il
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 750 VOLTS AC RMS, YOU
MIGHT DAMAGE YOUR METER AND EXPOSE YOURSELF
TO ASEVERE SHOCK HAZARD.
Follow these steps to measure the frequency of a signal.
1. Set the function control to
Hz. K Ez appears on the
display.
2. Plug the red test lead into
the + jack, and plug the
black test lead into the
-COM jack.
Black Red
3. Connect the black test
probe to a ground
reference for the signal,
and connect the red test
probe to the signal source.
The meter displays the
measured frequencY from
0 to 2.000 MHz.
ffil
P"ffiffjm"
34 35

Notes: MEASURING CAPACITANCE
o The meter uses a 1 Hz gate signal to measure the fre. Before you measure capacitance, fully discharge the capaci-
quency of signals below 4000 Hz. You might have to wa1 a tors. Follow these steps to measure capacitance.
few seconds for the display to stabilize.
o For signals above 4000 Hz, you might have to manually set
the frequency range to prevent the meter from displaying a
harmonic of the actual frequency. See',Manually Sel-ecting
the Range."
o Because measuring frequencies takes several seconds, the
keypad might be slow to respond to key presses.
o Measuring frequencies above 100 kHz might cause BATT
to appear on the display. lf this happens, switch the meter to
another mode. lf BATI still appears, the batteries might
need to be replaced.
1. Set the function control to
-l F. nF appears on the
display.
2. Plug the red test lead into
the + jack, and plug the
black test lead into the
-COM jack. Black Red c
3. Attach the red test probe
to the capacitor's * side,
and attach the black test
probe to the capacitor's
negative side.
Or, plug the capacitor into
thE DIODE/OHMS/CAP
socket. (Observe the
polarity for electrolytic
caoacitors.)
4. Read the measured
value on the display.
36 37

Notes:
. An electrolytic capacitor's measured capacitance changes
depending upon the voltage applied to the capacitor. 6e_
cause this meter cannot use high voltages to set the elec_
trolyte, it cannot measure the absolute cipacitance value.
o The lowest capacitance ranges have an internal capaci_
tance that is the actual input capacitance of the instrument.
lf you want to make measurements at very low ranges, sub_
tract the internal capacitance from the measurements.
USING THE HOLD FUNCTION
The hold function letslou freezethe measurement reading on
the meter's display. This function is useful when there'are
many voltage changes and you need a snapshot of the volt_
age.
To use the hold function, connect the test probes to the compo_
1e1t 9f circuit you want to measure. When you want the meter
lg n{O the reading, press DATA HOLD. The reading locks on
the display and HoLD appears. ln the hold mode,lhe meter
cannot take any more measurements. To clear the hold read-
ing and allow the meter to resume normal operation, press
DATA HOLD again.
ooo@@-ol
AUTO
L RnHGE selecr j
USING THE BAR GRAPH
ln addition to the numeric display, the meter displays all meas-
urements on a bar graph at the bottom ol the display. The bar
graph is updated more quickly than the digital display, and
gives a better indication of levels and trends for varying meas-
urements. The bar graph has 41 marks. The first mark is al-
ways on, and indicates 0. Each additional mark represents the
first two digits in the display.
For example, if the displayed value is 1 .853, 19 marks appear
on the bar graph.
- loooooooooooooolooo. 2s s * .o F
f.\
For DC functions, a minus sign (-) appears to the left of the
bar graph to indicate negative polarity.
MANUALLY SELECTING THE RANGE
The meter automatically selects the best range for most appli-
cations. For some situations, you might want to manually set
the range. To switch to the manual mode, press MANUAUAUTO
so AUTO disappears from the display. Then press RANGE
DOWN or RANGE UP to select the range.
frc d8 AUTO 0ATA
' RANGE sELEcr -l mLD
To return to automatic range selection, press MANUAUAUTO
so AUTO appears on the display.
+
38
dB DATA
HOLO
39