B+K precision 2831C User manual

lnstruction
Manual
Model
2831C3llzDigit
BenchType
Digital
Multimeter

TEST
INSTRUMENT
SAFETY
WARNING
I
An electrical
shock
causing
l0 milliamps
of current
topass
throulhthe
heartwill stop
mosthuman
heartbeats.
Voltage
aslow
as35volts
dcoracrms
should
beconsidered
dangerous
and
hazardotrs
since
it canproduie
afatal
cgrrent
gnder
certain
conditions.
Higher
voltages
areeven
more
dangerous.
Observe
the
following
safetyprecautions:
l. Donotexceed
thefollowinginput
ratings.
Personal
injury
ordamage
totheinstrument
may
result.
DC
VOLTS (Range
2v-lkv) 1200V (dc+ac
$eak) DC
VOLTS
(Range
200mv)
750V
(dc+ac
pk)
ACVOLTS (Range
2V-lkv) 1000V rms ACVOLTS
(Range
200mv)
750V
rms
OHMS
2001tA*2
A
204
COM
450
V dc
oracnns
2A (fuse protected)
20A (untused)
Donotfloat
morethan
500volts
fromearth
sround.
2. Removetestleadsffom the instrumentandpoint of measurement
beforereplacingfuses
or performing anyservicing on the
multimeter.
3. Use
only shrouded
safety
typetestleads
likethosesupplied.
Periodically
inspect
insulation
for any
burns,
cuts,
orbreaks.
Neverusetest
leads
with exposed
barewires
orpoor insulation.
4. Turn offequipmentwhile making
test
comections
in high-voltagg
circuits.
removing
power. Discharge
high-voltagecapacitors
after
5. For voltage
or current
measwements
in highvoltage
equipment,
donottouch
equipment,
meter,ortestleads
while poweris
applied.
6. If possible,
famlliarizeyourself
with theequipment
beingtested
and
thelocation
of itshighvoltage points.
However,
remember
thathigh voltage may appear
atunexpectedpointsin d6fectiveequipment.
7. Useaninsulated
floor material
or floormatto standon,andanin5ulated
work benchsurface:
makecertain
such
surfacesare
not dampor wet. (continued
oninside
back
cover)

InstructionManual
for
Model2831C
BenchType
3-112
Digit
MULTIMETER
KKPRECilsffEJ
1031
Segovia
Circle,Placentia
CA
92870

TABLE
OFCONTENTS
Page
TEST INSTRUMENT SAFETY .InsideFront Cover
INTRODUCTION. .......I
SPECIFICATIONS. .......2
OPTIONALACCESSORIES... .........5
CONTROLSANDINDICATORS ......,.6
CONTROLSANDINDICATORS ........7
OPERATINGINSTRUCTIONS.. ........8
Preliminary .....8
VoltageMeasurements ........8
Page
CurrentMeasurements
... ..........9
ResistanceMeasurements
... .......9
ContinuityTesting ....10
DiodeTesting... ....10
MI{TNTENANCE.. ...... II
huseReplacement ....11
lineVoltageSelection .......12
f,estleads .....12
InstrumentRepairService .....12
WARRANTY
SERVICEINSTRUCTIONS.. .....14
LIMITEDONE-YEARWARRANTY.... .......15

INTRODUCTION
The B & K PrecisionModel 28318 bench-type3-ll2
digit multimeter is a highly versatile instrument offering
standardfunctions of voltage, current (with a 20 A range),
and resistance
measurements.
[n addition, it also includes
diodetestandcontinuity functions.
The instrument is easy to use, as all functions are
selected
from apanel
of very logically laidout andidentified
pushbuttons.
The 3-ll2 digit LED display features0.43"'
digits
with automatic
minussignand
auto-zero
capability.
The unit is housed
in a rugged,
attractive
plasticcase, andthe
carrying
handledoubles
asa sturdy
tilt stand.
Thetilt standcan
be folded on top of the instrumentto allow stacking with your
other instrument.
Safety featuresinclude safetyjacks, safety test leads,and
extensive
overload
protection,including
ahighenergy
fuse.
B & K Precision offersa full line of optionalaccessories
for the Model 28318 which canfurtherexpand
thecapabilities
and usefulness
of the instrument.Pleasecontact your locai
B & K Precision distributor or B & K Precision for more
information
onthelatestaccessories.

SPECIFICATIONS
All accuraciesspecified
at23"C + 5 oC,757o
maximum AC VOLTAGE
relativehumidity.
DCVOLTAGE
RANGE MAXIMUM
INDICATION ACCURACY MAX
INPUT
200mV t199.9mV
!(O.1o/oof reading
+
1
count)
Allranges
750V
(dc+acpeak)
2V 11.999
V1200v
(dc+ac
peak)
20v +19.99V
200v 1199.9V
1200v 11200
v
Max.Input
Normalmoderejection: 50dB minimumat 50160
Hz.
Commonmoderejection: 120dB minimumatdcand
50160Hz with I kO unbalance.
I second.
InputImpedance: 10MO.
ptoducl
Inputimpedance. 10MClin
parallelwith
100
pF.
Commonmode
rejection: 60 dBminimum
at5060 Hz.
Response
time: 3seconds
maximum.
Responsetime:
TRIIE RMS:FROM lE/o tD10V/o
OFRANGE
RANGE I/IAXIMUM INDICATIONFREQENCY ACCRACY
MAX
INPUT
VOLTAGE
200mV '199.9mV 4oFtsb1Kl-E
1KFtsb10Kt-E
10Klkb20Klh
nrcb.b&Ki
t(0.5%oftdg+46651
t(2% ofrdg+acnbl
t(5% oftdg{'4cnb1
t(1flo ofrdg+46651 750
Vrms
2V 1.gSSV 4or-tsb
1Kt-b
1KFLto
10KJ-L
10Kt-tsb20Klb
20K]-tsb40KlE
(0.5% ofrdg+acnbl
(2/o oftdgr<q6;
(5% oftdg+4cnts)
(1ry0 ofrdq+4cnb) 1000
V
rms
20v 't9.99V 4oFtsbl Klh
1Khtrtc
10KFL
10Kl-tsb20KI-L
20Kl-tsb40KlL
t(0.5%ofrdg+4cnb)
{2% ofrdg+acnbl
t(5% oftdg+466;
t(ltrlo ofrdg+4665;
200v 199.9/ 40Flzto 1KHz
1KFlzto
10Kl-lzt(0.5%oftdg+acnt)
t(2% ofrdg+4cnts;
1000v 1000
v
Max.Inpul A0tLlo 1lG-lz{0.5% ofrdg+cnb)
*Notto exceedthe
Volt-Her?uoduct of

SPECIFICATIONS
DCCTIRRENT
RANGE MAXIMUM
INDICATION ACCURACY MAXIMUM
INPUT
200uA 1199.9 uA L(0.2%
ofreading
+ 1count) 2A
2mA t1.999
mA
20mA t19.99mA
200mA t199.9
mA
2000mA t1999
mA r(0.3%
ofreading
+ 1
count)
204 119.99
A20A
through
20
Ainput
iaqk
Maximum burden
voltage: 0.3V at200mA.
(with supplied I V at2000mA.
AC CURRENT
TRUERMS:FROM lUY"
ta ljV/o OFRANGE
Maximumburden
voltage: 0.3V at200mA.
(with supplied 1V at
2000mA.
test
leads)
Response
time:
2.5Y (0.25
V across
20A
jacks)
at
20A.
I second.
Overload
protection: 2 N250V fusein
series
onmA input
jack.
20A rangeunfused.
testleads)
Response
time:
2.5V (0-25 V across
20A
jacks)
at20 A.
3 second.
Overload
protection: 2 N250V fuseinseries
on
mAinput
jack.
20A
ranseunfused.
RANGE MAXIMUM
INDICATIONFREQUENCY ACCURACY MAXIMUM
INPUT
200
pA 199.9
pA 40Hzto10KHz
10KHzto20KHz t(1%ofrdg+4cnb'
{2% ofrdg+acnE'
2A
2mA 1.999
mA 40Hzto10KHz
1OKFlzto20KHz
{1% oftdg+4orb)
t(2% ofrdg+4cnb)
20mA 19.99
mA 40Hzto
1OKHz
lOKHzto20KHzt(1%oftdg+4cnb;
t(2% ofrdg+acnbl
200mA 199.9mA 40Hzto
10KHz
1OKHzto20KHz t(1% ofrdg+qcnS)
{2% ofrdg+4cr"ts)
2000
mA 1999mA 4OHztoZKHz (1% ofrdo+4cntsl
204 19.99
A4OHzto2KHz t(1%ofrdg+acnts;
20Ahrough
Z0Ainputiac*

SPECIFICATIONS
RESISTANCE
RANGE MAXIMUM
NDICATION ACCUR,ACY TEST
SURRENTOVERLOAD PROTECTION
200
o199.9c) 1(0.2%
of
rdq+2cntsl 4.2m4
450V
dc/acrms
Allranges
2Kl) 1.999
KC)
{0.2% ofrdg+1cnt)
42O
uA
20
Kf) 19.99
Kc) 42 uA
200Kc) 199.9KC) 4.2
uA
2000Kc) 1999Kc) 0.42
uA
20
MO 19.99
Mo t (0.5%
ofdq+1cnts) 0.042
uA
GENERAL SPECIF'ICATIONS
Temperature
range:
Operating:
Storage:
0'C to
+40t.
-20"C to
+60'C.
Humidity range: 90%omaximumto +3511
.except
80oZmaximumon 2000
k O and
20M O range.
70Yomaximum
to+40t (non-condensing).
opencircuit
volage: 5 V maximum
loaded
with Maximum
common 500
v'
l0 M e r4ueuwrtl modevoltage:
Display: LED, 0.43"character
height.
Response
time: 3 second
( 20 seconds
on
20 MO range
) Power
requirements: 100/120/2201240
Y, 50160Hz,
5W.
DIODETEST Dimeensions
([xHxD): 261 x
7t x 2ll mm
Tested
on2 Kf) range. I mA test
current. (10.21
x 2.j9 x 8.3)in
CONTINUITY weight: r.63Kg (3.6
lbs).
Audio tone
soundswhen
resistance
islessthanl0 ohms
typical. Accessories
supplied: Testleads (2)
Instruction
manual
(l)
Spare2Atuse(2)

OPTIONAL
ACCESSORIES
ModelPR-21
Isolatior/Direct
Probe
ModelTP-30B
Temoerature
Probe
Model PR-23
Demodulator
Probe
I
I
AdditionalAfcessories:
TL-2A
ReplacementTestLeads
ModelPR-28A
High-voltageProbe
See
yourlocal
B & K Precision
distributor
formore
details.

GONTROLS
AND
INDICATORS
l. V-O Jack Inputjack for volhge measuremen!
resistance
measurement.
Diodetest andcontinuitytest.
2. COMmon Jaclc Inputforcommontestleadforall
measuremeffs.
3.mA Jack Inputfor200 pA to 2A dcorac
currentranges.
4. 20A Jack Inputfor 20 ampdcoraccurent range.
5.AC/DC Switch. Selectsacor dcin voltage
and
currentfimctions.
Engage
switch(setto "in" position) for ac;disengage
(setto',ouf'
position)for dc.
6. V Switch. Selectsvoltage
fi.rnction.
7. A (amp) Switch. Selects
currentfirnction.
8. )F ) O Switch. Selectsdiode test finction, resistance
firnctions,andcontinuitytestfi.mction.
Whenboth200 O and2 K
resistance fi.nction are selected, this switch enables audible
continuity test. Continuity tone is enabled when switches are
engaged.
g. 2MmY/200pN200CU +f r)) Switch. Selecrs200mV
rangefor acldc voltagefunctions, 200pA rangefor acldc
currentfunctions,and200 C)rangefor resistance
function.
Enables
continuity
testinconjunction
withswitch
(8)and (10).
rc.zVnmA KCy iF Switctr. Selects
2V rangeforacldc
voltage
finctions. 2 mA range
for acldccurrent
fi.urctions,and2 Kf) range
for resistance
firnction.
Also selectsdiodetest
( tF ) function.
ll .20 Vn0 mA/20 I(O Switch. Selects20V rangefor ac,/dc
I voltagefinctions. 20mA rangefor ac,/dc
currentfimctions,
and
20K,f2range
forresistance
function.
12.200VD00 mAn00 KC)Switch. Selects200V rangeforac/dc
voltagefunctions.
200mA rangefor addc ctnrent
finctions,
and
200Kf) rangeforresistance
function.
13.
1200VDC/1000
VAC2000 mA/2000
KQ Switch. Selects
1200
V range
for dcvoltage
function,1000
V rangefor acvoltage
firnctiorl 2000mAQ A) rangefor acldccurrent
fi-rnctions,
and
2000Kf) (2 Mf)) rangeforresistance
function.
4.20 AnI MQ Switch. Selects20A range
for acldccurrent
fi.mc-
tions.Usedin co4junction
with 20Ajack (a).Also selects
20MC)
range
for resistance
frmction
15.POWER Switch. Tumsinstument ON and
OFF.Power-onind-
icated
by presence
ofcharacters
ondisplay.
16 Display. 3-ln dlgtLED displaywifh automatic
decimal
point
and
mimrsC) sigr. Indicatesto 1999
counts.
Overrange
indicated
by a"1" displayed
atthelefonostdigit while all other
digitsrernain
blank

CONTROLS
ANDINDICATORS
Y/o/->/"0 +t.8"'8.8.
7 B 9
Fig. 1.Controls
and indicators
,7

OPERATING
INSTRUCTIONS
Use of test equipment mqy expose the
operator to electric shock hazards. Observe
all instructions contained in the TEST
INSTRUMENT SAFETY section of this
manual Before usingthis instrument.
The TEST INSTRUMENT SAFETY section
of this manual lists maximum voltage and
current input limits which mustbe observed.
Failure to adhere to theselimits may result
in damageto the instrument.
PRELIMINARY
Plugtheunit into anacoutletof theappropriate
voltage
andturn it onby depressing
thePOWER switch.
VOLTAGE MEASUREMENTS
l. PresstheV function
switch.
2. Select
acor dcmeasurement
using
theAC/DC switch.
Set
for dc nreasurement
by settingswitch to disengaged
("out
") position.
Push
switch
"in" for acmeasurement.
3.If the voltage
to bemeasured
isunknown, startwith the
1200VDC/I000 VAC range.
4.lf anapproximate
voltagerange
isknown,simplypress
the
switch for therange
desired.
Greatestresolutionis attained
using the rangeclosest
to an over range for the voltage
beingmeasured.
5.Connect
the
redtest
leadtotheV-O jack andthe
black
test
leadto theCOM jack.
6.Connect the test leads across the circuit noints to be
measured.
7.Read
themeasured
value
from the
display.

OPERATING
INSTRUCTIONS
CURRENT
MEASUREMENTS
For current meqsurements,
the meter must
be connected in series wilh the load. If
incorrectly connected (in parallel with the
load), the meter presents a very low
impedance
(almost a short), which may blow
the
fuse or damage
the meteror equipment
under test. The 20 A range has on fuse
protection and moy severely damage the
meter or equipment under test or cause
personal injury.
For current meesurements
greater thun 2 A,
high curent testleads should be used.High
current measurements with standard test
leads could causethe leads to heat up. This
nol only affects the accuracy of the
meqsurement,but could result in injury to
the operator.
1.PresstheA function
switch.
2.Select acor dcmeasurement
usingtheAC/DC switch.Set
for
dcmeasurement
by setting
switchto "out" position.Push
switch "in" for acmeasurement.
3.If thecurrent
to bemeasured
isunknown.
startwith themeter
in the20 A range,
usingthe20 A jack. If theexpectedcurrent
might exceed
2 A, usehigh currenttestleads. s
4.lf m approximate
currentrangeis known, simply press the
switchfor therangedesired.Greatest
resolutionisattainedusing
therange
closestto anoverange for thecurrentbeingmeasured.
a.For currentmeasurements
of 2 A or less,connectthe red test
leadto the2 A jackandtheblacktestleadto theCOM jack.
b.Forcurent measurements
greater
than
2 A, connect aredhigh
currenttest
leadto the
20Ajack andconnect ablackhigh
cuftent test
leadto theCOM jack.
5. Removepowerfrom the circuit rurdermeasurementandopen
the
normal circuit path where the measurementis to be taken.
Connectthe metsrin serleswith thecircuit.
6.Apply porvertothecircuit and
readthemeasuredvalueonthe
display.
RESISTANCE
M
EASUREMENTS
L Remove
powerfrom theequipmentundertest.
2.Pressthe
fJ functionswitch.
3.Connect
the red testleadto the V -O jack andblacktest
leadto theCOM jack. The
redleadis (+) polarity.
4.Connect
thetestleadsto thedesired
pointof measurement
andobserve
thereadingonthedisplay.
5.If the expectedresistance
rangeisunknown, startwith the
lowest range. If an overrange is indicated, continue
selecting higher ranges until the overrange indication
ceases.At thisrange,
greatest
resolutionisachieved.

OPERATINGINSTRUCTIONS
CONTINUITY
TESTING
l. Remove
powerfrom theequipmentundertest.
2.PresstheO switch.
3.Selectboth 200 Q and2 KC)resistanceranges
(pressboth
200 and2 K switches
simultaneously).
4.Connect theredtestleadto theV -Ojack andtheblacktest
leadto theCOM jack. Thered leadis(+) polarity.
5.Connectthetest
leadsto thedesiredmeasruement
points.
6.If theresistance betweenthetwo points isless than 10
ohms
(tlpical), thecontinuitytonewill sound.
7.Disengagingone of the two switches(200 O and 2 KC)
switchat "out" position) will disablethe continuity tone.
The instrument will then be operating in standard ohms
mode.
DIODETESTING
1.
PresstheQ switch.
2.Press the2 K switch.
3.Connecttheredtestleadto theV -fi jack andtheblacktest
leadto the COM jack. The redleadis (+) polarity. The meter
usesconventional-currentlead
polarity
for diodetesting
(i.e.
currentflow assumed
from positive-to-negative).
4.To checkdiodeforwardvoltage
(Vr), connecttheredtestleadto
theanodeandtheblacktestleadto thecathode.Diodesand
semiconductor
junctions
with normalV, of lessthan2.0V can
bechecked.
5.The display indicatesdiodeforward voltage.Normaldiode
voltagesareapproximately0.3 V for germanium
diodes,0.6
V for silicondevices,and1.6V for lightemittingdiode
(LED's).
An overrange indicates
anopendiode.A shorteddiodereads
near0 V.
6.To check the
reverse-bias
condition
ofa diode,reversethetestlead
connectionstothedevice.Thereadingshouldbethesame
aswith
opentestleads
(anoverrange).A lower readingindicatesa
leakydiode.
l0

MAINTENANCE
The following instructions are for use by
qualified service personnel only. To avoid
electrical shock, de not perform servicing
other than containedin the operating instru-
ctions unless
you are qualified to do so.
Remember
that ac line voltage ispresent on
line voltage input circuits any time the instr- l
ument is plugged into an ac outlet, even if I
turned off. Always unplug the unit before !
perforning servicingprocedures. .
FUSE REPLACEMENT
There are two fuses in the unit - one for the mA current
rangeand onefor the main power supply. If your unit continpes
to operate
(digitslit) but failsto measure
current,
check
thetwo
current fuses.
GurrentRange
Fuse
Note: The fusemostlikely to openfirstcanbe inspected
and
changed
withoutcase
removal.It is locatedon therear
panel
of
the unit. Simply use a flat blade screwdriver to rotate the
terminalcounterclockwise.
Then removetheentireassembly,
including
thefuse.If this fLseis
blown, replaceit with the appropriate
2 A,250 V, 5 x 20 mm fast-
blow firse @art number 196-300-2-000).
Then replace the
fineholder.
PowerSupply
Fuse
If your unit doesnot operateat all (no digits lit), checkpower
supplyfi4e (See
Fig.2) . Note:This fuseshould
not openunless
some defect occurs in the instrument, Replace it only after
investigationof thereason
for itsopening.
Usetheappropriate
value:
0.25 A, 250 V, fast-blow Sart number 196-300-0-250)
for
100/120Voperatiorlor 125mA, 250 V, fast-blow(part number
I96-300-0- I25\ for220/240
V operation.
ll

MAINTENANCE
LINEV9LTAGE
SELEGTI9N TEST
LEADS
Periodically examine the test leads to ensure that the
Thisinstrument
istheuniversal
line operation:
100V, 120V, conductors
arenot intermittent
orbroken..Also make
sure
that
220y and240v. Thebelow is explaining
theuser
how to good contact
pressure
existsatthetestleadreceptacles.
Keep
theseareasfree from dirt and corrosion. Use shroudedsafeW
chargefuse. type replacement
testleads.
l. Extract
thetuse
drawer
from theAC socketwith theaid INSTRUMENT REPAIR SERVICE
of ascrewdrive
(Theextra
safe
fusedrawercan
only be Because
of the specialized
skills andtestequipment
required
extractedwith theaid of a flat bladescre\4
' . for inskument repair and calibration' many customersprefer to
'qrlver') rely upon B & k Precision for this service.We maintain a
2. Pull outthefuse
from thefuse
holderandcharge
thefuse network of B & K Precision authorized
service
agenciesfor
this purpose. To usethis service, even if the instrument is no
rating in accordance
with specific required' longer under warranty, follow the instructions given in the
3. Pluggingfuse
holderinto theLine voltage
indication WARRANTY SERVICE INSTRUCTIONS section of this
shown on thefusedrawer is correct.Rotating the fuse T;;Xl*.tn"re is a nominal charge for instruments out of
holderbefore
insert
fusedrawer
to have
correctvoltase
indication.
4. Installthefusedrawer
into AC sollect.
t2

n ru'trff Fust
lB 6 996p159
O,|intfI
r'UI FIJST
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lr i\l
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llrs EouFil€r{r LJsTr tr[rHED.
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-'A u" (D)Fuse
rink
Mlll Fhln'eiusel
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rilh voltogeselector
Iiio.qe-ncPowersource|
(B)Fuse
drorer
l3

WARRANTY
SERVICEINSTRUCTIONS
Warranty Service: Pleaseretum the product in the originalpackaging
with proof of purchase to the below address.Clearly
statein writing the performance problem and retum any leads,comectors and accessories
that you areusing with the device.
ContactB&K Precisionto obtaina Return Authorization numberbeforeshippingtheproduct
to B&K. The RA number must
appear
on theaddresslabel.
Non-Warranty Service: Return the product in the original packaging to the below address.Clearly state in writing the
performanceproblem
andreturnanyleads,connectors
andaccessoribsthatyou areusingwith thedevice.Customersnot onopen
accountmust include payment in the form of a money order or credit card.For themost currentrepair charges
contactthe factory
beforeshippingtheproduct. ContactB&K Precision to obtaina Rdturn Authorization numberbeforeshipping theproduct to
B&K. The RA number mustappear
ontheaddresslabel.
Return all merchandiseto B&K Precision Corp. with pre-paid shipping. The flat-rate repair chargeincludes return shipping to
locationsin North America.For overnightshipmentsand
non-NorthAmericashippingfeescontactB&K PrecisionCorp..
B&K Precision Corp. Phone: [phone]
1031Segovia Circle Facsimile:714-237-9214
Placentia,
C492870 Email:[email protected]
www.bkprecision.com
Includewith the instrument
your completereturnshippingaddress,contactname, phonenumberand
description
ofproblem.
l4

LTMITEDONE-YEAR
WARRANTY
B&K Precision Corp. warrants to the original purchaser
that its product and the component parts thereof, will be free from
defectsin workmanship and materialsfor aperiod of oneyearfrom the dateof purchase.
B&K Precision Corp. will without charge,
repair or replace,at its' option, defective
productor component
parts.Returned
product
mustbeaccompanied
by proof of thepurchase
datein theform asales
receipt.
To obtainwarranty
coverage
in theU.S.A.,thisproductmustberegistered
by completing
andmailingtheenclosed
warrantycard
to B&K PrecisionCorp., l03l Segovia
Circle,Placentia,CA92870 within fifteen
(15)daysflom proofof purchase.
Exclusions:
This warranty does
not apply in the event pf misuse
or abuse
of the product or asa resultof unauthorized
alternations or repairs. It isvoid if the serial number isqlternated, defaced
or removed.
B&K Precision Corp. shall not be liable for any consequintial
damages,includingwithout limitationdamages
resulting
from
lossof use.
Somestatesdo not allow limitation of incidental
or consequential
damages,
sotheabovelimitationor exclusion
may
notapplytoyou.
Thiswarranty
givesyou specific rightsand
you mayhaveother rights,which varyfrom state-to-state.
15

TEST
INSTRUMENTSAFEW
(continuedfrom inside front cover)
8. Keep "one hand in the pocket" while handing an instrument probe. Be particularly careful to avoid contacting a nearby
metal objectthat could provide agood groundrehrrn
path.
9. Whenusingaprobe, touchonlytheinsulated
portion.
Nevertouchtheexposedtip portion.
lO.Someequipmentwith atwo-wire ac
powercord,includingsome with polarizedpowerplugs, isthe"hot chassis"type.This
includesmostrecent
televisionreceivers
andaudio
eqgipment.A plastic or wooden
cabinet
insulatesthe chassis
to protect
the customer.When the cabinet is removed for servicipg, a seriousshockhazardexists if the chassisis touched.Not only
doesthis present a dangerousshockhazard,but damagg to testinstrumentsor the equipmentundertestmay result.To make
measurementsin "hot chassis"equipment,always cofflect an isolation transformerbetweenthe acoutlet andthe equipment
undertest.TheB & K PrecisionModel TR-l10 or l6Q4
IsolationTransformer,or Model 1653or l655AC PowerSupplyis
suitablefor mostapplications.To be on the safeside,
peatall two-wire acpowered
equipmentas
"hot chassis"unless
you
aresureit hasanisolatedchassisor anearthgroundchtissis.
l1.B & K Precisionproducts
arenot authorizedfor use
in anyapplicationinvolving directcontactbetweenour product
and
the humanbody, or for useasa critical componentinja life support device or system.Here, "direct contact" refersto any
connectionfrom or to our equipmentvia any cabling op switching means.A "critical componentof a life supportdeviceor
systemwhosefailure to perform canbe reasonablyexpectedto cause
failure ofthat device or system,or to affect its safety
or effectiveness.
l2.When testingac
powered
equipment,rememberthataqlinevoltageisusually
present
on some
powerinputcircuits suchas
on-off switch, fuses,power transformer,etc. any time the equipment is connected
to an ac outlet, even if the equipmentis
tumed off.
13.Neverwork alone.Someoneshould
benearbyto render
aid if necessary.Trainingin CPR(cardio-pulmonary
resuscitation)
first aid ishighly recommended.