Simpson 215 User manual

INSTRUM ACCURATE

43
OPERATOR'S
MANUAL
MODEL 2r5
VOLT-OHM.MILLIAMMETER
SIIilPSON ELECTRIC COIt[P.f,NY
5200-18 West Kinzie Street, Chlcogo 44, Illinob
In Cqncdc, Bcch-Simpson, Ltd., London, Oniario

Figure I Simpson Modet 215 VolrOhm'Millidmmelet
Sizet 5r/2"x7"x3%". Weight 3yr lbs.

TABLE
OF CONTENTS
SECNON I GENERAT DESCNIPTION
Generql Introduction
Meosurement
Ronges
Avqiloble...........
D.C. Voltage
A.C. Voltoge
A.F.Output
Voltcge..............................
Volumelevel in Decibels....................
D.C. Resistqnce
Current in D.C.Circuits
D,C. Voltoge Meqsurements
A.C. Voltoge Meosurements.
D.C. Resistcrnce
Meqsurements..............
Current Meosurementsin D.C.Circuits..
SECTION II
PAR. PAGE
t7
27
2d7
2b8
2c8
2d8
2eB
2II
38
49
qo
69
OPERATING INSTRUCI'IONS
D.C.
VoltogeMeosurements
0-1000
V............
A.C. VoltogeMeosurements
0-1000
V............
A.F. Output Meosurements.
VolumeLevel Meqsurements............................
D.C.Resistqnce
Meqsurements
.......................
Curtent Meosutementsin D.C.
Circuits............
FUNCNOMNG OF PARTS
D.C. Voltmeter
A.C. Voltmeter
A.F. OutputMeter ............
Volume Level Meter.........
D.C.
Ohmmeter
.................
D.C. Milliommeter
SECTION IV MAINTENANCE
I
2
,,. o
I
l0
1l
ll
l2
l3
SECTION III
.l
.2
.J
,4
.o
l,
I4
t5
t6
I6
L7
I
J
4
19
l9
t9
23

SECNON V SUPPLEMENTARY DATA PAR. PAGE
Model 215
cs q Condenser
Tester............. | 24
RMA Resistor Color Code Chort................ 2 27
RMA Mico CopocitorColor
CodeChort..................3 28
Volts-Decibels
Conversion Tcble................ 4 29
Ccpccitive Reoclcrnces 5 30
Audio Frequencies......... 5c 30
RodioFrequencies
.................. 5b 30
Figure I
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8<r
Figure 8b
Figure I
Figure lOc
Figure lOb
Figure ll
Figure 12
Figure 13
IIST OF ILLUSTRATIONS
PAGE
Simpson Model 215 VolfOhm Milliqmmeter... 2
SimpliliedD.C.Voltmeter
Circuit........................................
14
SimplifiedA.C. VoltmeterCircuit...........................................
15
Simplilied
OutputMeterCircuit
............................................
l6
Ohmmeter Circuit with SelectorSwitch in PositionRxl .......16
Ohmmetet Circuit with Selector Switch in Position Rxl00 . 17
Ohmmeter Circuit with Selector Switch in Position Rxl,000 17
Simplilied
MicroommeterCircuit.............................................
l8
Simplilied
MilliommeterCircuit.............................................
l8
Model 215Schemotic
Dio9rom........... .............
20
Model 215
PortsLoyout-Reqr View....................................
2l
Model 2I5 Ports Loyout-Recr View oI Front Pcnel.............22
Model 215Usedos Condenser
Tester......................................
25
RMA Resisto!ColorCodeChort
.....-.-.....................................
27
RMA Mico Copocitor
ColorCode
Chort................
..................
28
I
I
I
I
-J

%orrc'r,aortd
As the purchcser of c Simpson 215 you qre now the owner
of one of the most fqmous testing instruments in the world.
Compcct, oI relctively high sensitivity (200microamperes full
scqle), the Model 215 hcs eqrned its top-rcnking reputction
qs the result of quclity construction joined to exceptioncl
engineering versctility. This engineering superiority is, in
turn, the product of invclucble yecrs of experience with
every single unit comprising the complete cssembly.
In no other instrument of its kind do you find fectures such
qs qre contqined in the Simpson Model 215.
Its trim, scientific
qppecrqnce - the 4Yz" modernistic instrument, the hecvy
bckelite cqse, the neqt bckelite pcnel - gives evidence of
inner quclity. These hidden feqtures qre too numerous to
mention here, but yow pride in your new instrument will
grow crsyou lecrn oI them. Pqrts qre qssembled cnd plcced
in position so they ccrnnot become loose or detoched from
their origincl positions. All the sub-qssemblies qre mounted
on speciclly designed bqketite panels, or on c speciclly
designed sub-pcnel, mqde qnd engineered expressly for c
specific lunction in the Model 215.
When you purchase Simpson test equipment, you get equip-
ment mqde qlmost entirely within the vqrious plcnts of our
Compony. Ecch component pcrt of the 215hqs been designed
cnd completely tooled qnd mqnufqctured in our own plcrnts,
with the exception of the precision resistors qnd one or two
other functionolly leust importont parts. The Model 215,like

cll other Simpson testers, is not qn assembly job made up
from purchcsed parts such qs is true of the mcrjority oI testers
offered on the mqrket.
We cre by lor more self-contqined thcn crny other mqnufqc-
turer of test equipment. This is your qssurqnce thqt the
testers we olfer will not quickly become obsolete. Our tre'
mendous investment in expensive production tools is your
scfegucrd cgcinst obsolescence cnd {urther qssuronce of
unvcrying quclity.
Here qt Simpson we do not think of mcking instruments
merely to seII. We think of making instruments to serve' Our
interest in your Model 2I5 cnd in your sqtislcrction with it
never cecses. Thct is the reqson for this Operctor's Mcnuql'
We wqnt you to know how to get the most from your 215'
The Model 215 is c rugged instrument and will withstqnd q
grect decl of obuse. We urge you, however, to treqt it with
cqre qs its mechonism is qctuqlly more deliccrte thon thct of
a wqtch. If you will keep it cleqn, free from continuous,
severe vibrction and cvoid &opping it, your Model2l5 will
give you c liletime of qccurqte, dependcble service.

OPERATOR'S
MANUAT
SIMPSON MODET 2I5 VOLT.OHM.MNLIAMMETER
SECTIOII I
GE:NERAL
DESCRIPTION
I. GENERAI INTRODUCTION.
The Simpson
Model 2lS TestUnit olfers c small, compact
qnd complete
instrument
with high sensitivity
for testinqlnd
locnting trouble in cll types of circuits. Thd lcrge foui qnd
one,-hslf
inch meter provldes c long scalethat is 6csy b,;J
nld thecompactqucmgement
o{thecontrolsallows ihe over_
all size of the bckelite housing to be compcrctively smcll
for mcximum portobility.
It comescomplete with one set of red,ond blcck test leqds
wtih insuloted clips cnd operalor's mqnuql.
Theelectricql circuit is designedto give mqximum insurqnce
agcinst incccurccy cnd dcrmcgelo ihe component
pcrts. Im-
pregncted-coble wiring is used throughout.-All resistorscre
mqde to close tolerqncesfor cccurciy qnd qre firmlv heid
in plcce.onc specicl bckelite plcte mochinedfor thisprirpos-.
rhe entire cssembly is truly rugged qnd cqn well withitcnd
theweqr cnd teqr of theservicework Ior which it is designed.
Accurccy is 3% D.C.
cnd S%A.C.of full sccledeflectiol.
2. MEASUREMENT
RANGESAVAIIABIE
c. D. C.VOLTAGE
0-2.5 volts
0-10 volts
0-50 volts
0-250volts
0-1000
volts
lat '. -
to, *# i,r
ff0$ohms per voltsensitivity
i)i.1.,

b. A. C.VOTTAGE.
0-2.5 volts \
0-10 volts I
0-50 volts ) 1,000ohms
pervoltsensitivity
0-250volts \
0-1000
volts /
.- {'ol 'Y;t'l\
A.F.OUTPUTVOITAGE.
0-2.5 volts \
0-10 volts I
0-50 volts ) .l Mf. interncrlseriescondenser
0-250volts \
0-1000volts /
d. VOTUME
TEVELIN DECIBEIS.
-l2to* 3decibels
0to f 15
decibels
f 14to f29 decibels
f2B to f43 decibels
*40 to f55 decibels
e. D.C.
RESISTANCE.
). ? k €-*o8o ohms ' :' (8&ohms center)
0
- i i .r k 0-400$€O
ohms I a '.'- (900S
ohms center)
' , \'e;;Afmegohms i2 ;),; r,- €&'00e
ohms cbnter)
f. dURRENT
IN D. C. CIRCUITS.
I i # '250microqmperes ?,f,' *0O millivolts
10 millicmperes
I00 milliomperes
500millicmperes
,:
1 Sy: " : y
;.
3. D. C. VOLTAGEMEASUREMENTS.
D. C. voltcge is mecsured by cpplying the unknown volt-
age to the meter through suitcble inteftgl series resistors.
Tfre
meterhas c full scqiesensitivity of d#microamperes at
7 ,ir, 2€ffmillivolts
with qninterncrl
resistqnce
of
L000phms,giving
the instrument cn overcll sensitivity of Sf00ohms per volt.
7a):
oc
8
Cqlibrcted Ior use
qcross c 500
ohm line
€SO.miltivelts--
-998*raillivolt+-
-999.6-nillivolls
I
1

4. A. C. VOTTAGE MEASUREMENTS.
A. C_.voltqge mecrsurements, including output cnd decibel
readings, qre mqde possible by the usebf cn internal copper
oxide rectifier connected in series with the meter. A precision
wound internql shunt resistor is connected in pctclel with
the meter resulting in crsensitivity oI 1,000
ohmi per volt.
5. D. C. RESISTANCE MEASUREMENTS.
D. C. resistance is meqsured by the use of suitqble internql
series qnd shunt resistors in series with c bcttery to give accu-
rqte scqle delledion of themeter when qn unknown iesistqnce
is to be meqsured.
6. CURRENT MEASUREMENTS IN D. C. CIRCUITS.
Current is meqsured by the use of suitcble internal shunts
so thct the mqximum current in each rqnge will prod.uce c
full sccle deflection of the meter.
SECTIOil II
OPENATING
INSTRUCTIONS
CAUTION: When making m_eqsurements,
turn ofl the power
tothe
circuit
under
test,
clipthe
test
leqdstothe desired-points
cnd thenturn on the powerto tcke thereading.
Turndtt tt e
powerto disconnect
themeter.
ZEROADIUSTMENT: Belore tcking recdings, be sure that
thepointer is on zero.
If pointeris olf zero,
cdiust by mecnsof
theslottedscrewlocqted
in thebcrkelite
cqse
direitly below
themeterscqleqsshownin Figure l. Usec smcll screil-driver
to turn this cdjtEtment slowly right or left until the pointer
is directly over the zeropoint on the scqle.
I. D. C. VOLTAGEMEASUREMENTS
O-IOOO
VOITS.
q. Plqce
the "OUTPUT-A.C.-D.C."
switchin the "D.C.,,
posi-
tion.
b. Rotcte the rcnge selectoi switch to cny one of the volt-
cae positions required. WHEN IN DOUBT OF THE VOLT-

AGE PRESENT,ATWAYS USE THE HIGIIEST RANGE AS A
PROTECTION TO THE METEB. After the first reading, the
switch cqn be reset to q lower rqnge, iI needed, to get c more
crccurcte recding.
c. Plug the blqck test lecd into the jcck mcrked "-" qnd
the red test lecd into the jcck mcrked "f". Clip the other end
of the blcck leod to the negcrtive side of the circuit to be
checked cnd the other end of the red lecd to the positive side.
d. Turn on the power to the circuit to be tested.If the pointer
dellects to the left ol zero, the connections qre incorrect. Turn
olf the power qnd reverse the position oI the test clips.
e. Reqd the voltcae on the blqck crc second from the top
mqrked "D.C."
For the 2.5volt rqnge use the 0-250figures crnddivide by 100.
For the 10, 15and 250 volt rqnges, reqd the figures directly.
For the 1000
volt rqnge, use the 0-I0 figures cnd multiply by
100.
2. A, C. VOTTAGEMEASUREMENTSO-IOOOVOITS.
q. Place the "OUTPUT-A.C.-D.C."
switch in the "A.C." posi-
tion.
b. Rotctethe rcnge selectorswitch to qny of the five rcrnges
required. WHEN IN DOttBT OF THE VOTTAGE PRESENT,
ATWAYS USETHE HIGHESTRANGE AS A PNOTECTION
TO THEMETER.
After the lirst recding the switch ccrnbe re-
set to c lower rcnge for c more occurqte recrding.
c. Plug the blqck test lecd into the jcck marked "-" qnd
the red test leqd into the jack mcrked "+". Clip the other
ends
oIthetestlecdstothetwo sides
ofthecircuit tobetested.
A.C. voltcge will recrd
correctly regcrdlessof which wcy the
testlecds qre connected.
d. Turn on the power to the circuit to be tested.
e. For the 2.5volt rcnge, recd the voltcge on the red crrc
secondfrom thebottom
mcrked "2,5V. A.C.Only."
For the other ronges use the red qrc third from the bottom
marked "4.C."
10

For the I0, 50cnd 250volt rqnges,reqd the figures directly.
For the 1000volt rqnge read the 0-10figures cnd multiply
by 100.
3. A. F. OUTPUT
MEASUREMENTb.
cr.Plcce the "OUTPUT-A.C.-D.C."
switch in the ,'OUTPUT,,
position. In this position qn internql condenseris connected
in seriesfor blocking out the D.C.componentwhen connec-
tions qre mcide directly to the plate oI a tube.
b. Rotcte
therangeselector
switchtocny of thefive rqnges
required. WHEN IN DOUBT OF TI{E VOLTAGE PRESENT,
AI.WAYS USETHE HIGHESTRANGE AS A PROTECTION
TO THE
METER.
After the first recdinq, the switch cqn be re-
setto q lower rcnge for c more qccurlte recding.
c. Plugtheblqck test
leadintothejcck mcrked "-,,cnd the
red testleod into the jcck marked-"f". Clip theotherends
of thetestleads to theoutputoI the circuit uridertest.
d. Turn on the power.
e. For the 2.5volt rcnge usethe red qrc second
lrom bottom
morked
"2.5V.A.C.
only".
For the other ronges, use the red qrc third from the bottom
mqrked"A.C."
Forthe 10,
50cnd 250
volt rqnges,
read thefiguresdirectly.
Forthe 1000
volt rqnge,
usethe0-I0figurescnd multiply by
r00.
The reqctance of the series condenser used when recding
output volts ccuses c slight error which vqries with frel
quency. This is exploined in pcrcarcph 3 of Section III.
4. VOTUME
LEVET
MEASUREMENTS.
c. Setthe
"OUTPUT-A.C.-D-C."
switch
inthe,,A.C.,,
position.
b. Rotctethe rcnge selectorswitch to cny oI the five rcnges
required.
c. Plug
the
test
lecdsintothetwojccksmcrked,,-,, cnd,,f ,,

cnd connect the clips to the two sides oI the circuit to be
checked.
d. Turn on the power crnd reqd decibels on the blcck crc qt
the bottom of the scqle mqrked "D.B." When recding deci-
bels, cdd clgebrcicclly to the scqle indicqtions, the num-
hers shown ct setting of range selector switch. For excmple,
i{ the sccle indicction is -4 DB with the switch in fhe IfDB
position, the true recding will be + 8DB.(f I2-4:f8).
5. D. C. RESISTANCE MEASUREMENTS.
CAUTION: Before mcking cny resistance meqsurements in a
radio circuit, be sure the current is turned ofI so thqt no volt-
cge exists. Otherwise the meter mcy be dcmaged.
q. Plcce the "OUTPUT-A.C.-D.C." switch in the "D.C." posi-
tion.
b. Rotote the rcnge selector switch to cny of the three rqnges
required.
Rxl for 0-4000 ohms.
Rxl00 for 0-400,000 ohms.
Rxl,000 for 0-4 megohms.
c. Plug the test leads into the two jacks mcrked "-" qnd
"f". Short the ends oI the leqds crnd set the pointer to zero
by rototing the "ZERO OHMS" knob.
d. Sepcrote the ends oI the test leads cnd clip them qcross
the portion of the circuit to be meqsured.
e. Read ohms on the blcck qrc ct the top of the scole.
For rcnge Rxl, recd the figures directly.
For range Rxl00, multiply the recding indiccted by 100 or
cdd two zeros.
For ronge Rx1,000multiply the recding indicated by 1,000or
qdd three zeros.
Excmple: A Yz meqohm resistor should be checked on the
Rxl,000 rqnge. The reading on the scale will be 500.Adding
three zeros will give 500,000ohms or /z meghom.
t2

CAUTION: Do not leqve the ronge selector switch set in q
resistqnce mecsurement position when the meter is not in
use cs test lecds may become shorted ond run down the
internql bcttery. It ls olso p_ossible
thct they moy be con_
nectedccrossc voltoge cccidentclly ond dariage ihe meter.
6. CUNRENT
MEASUREMENTS
IN D.C. CIRCUITS.
a.Plccethe"OUTPUT-A.C.-D.C."
switchin the',D.C.,,
position.
b. Rotate the rcnge selector switch to any of the rcmqes
le,gurqed,
WIIEN IN DOUBT OF TIIE CURhENTpRESEfrT,
ATWAYS USETHE HIGHESTRANGE AS A PBOTECT]OI.i
TO THE
METER.
Aiter thefirst reodinq, the switch cqn be re-
setto q lower rongeif needed.
c. Plug the blqck test leqd into the jack mcrked ,,_,, qnd
the red testleod into the jcck mcrked ,,9,,.
d' Breck the circuit to be tested
qnd insert themeterin series
by cgnnecting the red test leqd to the positive side qnd the
blcck test lecd to the other side.
e. Turn on the power.
f. lecd millicmperes on the blcck cncsecondfrom the top.
It the pointer is forced agcinst stop ct lelt oI sccle, the con_
nections qre incorrect. Turn off the power cnd reverse the
positionof the testclips.
For 250microomperes,reod the ligures 0-250
directly.
For l0 milliomperes read the figures directly.
For 100
milliomperes read thefigures 0-10
qndmultiply by 10.
For500millicmperes reqd thefigures0-50andmultiply by 10.
CAUTION:Forcurrentmecsurements,
themetermustclwqvs
be connectedin series with the circuit. Never ;.;";; ifl;
meterqcross
c voltcae sourcewhen therqnge selector
switch
rs set tor current meqsurement os this mcy domoge the
meter. Alwcys observe polarity.
13

SECTIOIT IU
FUNCTIONING OF PARTS
The complete schemqtic diogrcm o{ the Model 215 volt-ohm
millicmmeter is shown in Figure 9. The simpli{ied sections
qre described in the Iollowng pcrogrcphs.
I. D. C. VOLTMETER CIRCUIT-s,OOOOHMS PERVOLT.
Figure 2 shows the circuit used when the "OUTPUT-A.C.-
D.C." switch is in the "D.C." position cnd the rqnge selector
switch is in one oI the live voltcge positions.
The totcl resistcnce of the bonk oI multiplier resistors qnd
the meter is 5 megohms or 5,000,000
ohms from the 1,000
V.
position to the "NEG." jcck. Ohms lcrw will show thqt when
c 1,000
volt potenticl is opplied between the two jccks, c
current of 200 microomperes will flow through the circuit,
ccusing c lull sccle deflection oI the meter. Dividing the
number o{ ohms. 5,000,000,by the number of volts, I,000,
gives 5.000ohms which is the sensitivity per volt.
Figure 2 Simpll6ed D.C. Voltmeter Circuit
2. A.C, VOLTMETER CIRCUIT-IOOO OHMS PER VOTT.
Figure 3 shows the circuit used when the "OUTPUT-A.C.-
D.C." switch is in the "A.C." position cnd the range selector
switch is in one of the five voltcge positions.
In this circuit the A.C. is rectiJied by a copper oxide rectilier
to supply the microqmmeter with direct current. The other
hclf of the cycle pqsses qround the meter cnd through the
l4

rectifier^in
the opposite
direction
qs shownby theqrrows in
Figure 3. The shunt resistor R-24
cnd the serGsresistorR_23
are precisionwound qnd cclibrcted with the recti{ierwith
which lhey cre used. The resulting sensitivity is 1000
ohms
per volt.
RECTIFIER
Figure 3 Simplilied A.C. Voltmeter Circuit
3.A.F.
OUTPUT
METER.
Figure
4shows
the
circuit
used
when
the
,,OUTpUT-A.C.-D.C.,,
switch is in the "OUTPUT" position cnd the rcrnge selector
switch is in one oI the five voltage rqnges. This ii the sqme
qs the A.C. voltmeter exc-ept
thct c .I mfl condenser is plcced
in series with the "POS:" j-cck to block the D.C. component
when connection is mqde direct to the plote of c tube.
In recding-A.C. voltcAe with the output meter the impedance
of the blocking condenser which is in series with the voltcoe
multipliers must be token into cinsiderqtion. This will ccuie
considerable error ct 60 cycles but the percent of error will
decreqse with cn increqse in frequency.-The actuql elfective
resistqnce is egucl to VXF+HI where Xc is the ccpoci-
tive reqctonce of the .1 mfd condenser cnd R the multfp[er
resistqnce.
For the 2.5 volt rqnge R-2S00 ohms qnd Xc ct 60 cycles-
26,500
ohms.
Therefore
VzO-SOO'+Zmdt-26,618
ohms,
rhe
qctuql elfective resistqnci in the circuit.
t5,

RECTIFIER
POS
Figure 4 Simplilied Output Meter Circuil
4. VOLUME TEVEL METER.
The decibel is q unit oI meqsurement used in P.A. crnd tele.
phone work. When a .006 wqtt signql is dissipcted in q locrd
of 500 ohms, c potenticl of I.73 volts is developed qcross the
locd cnd it is qt this point thqt the zero is plcced on the deci-
bel sccle. Thus it cqn be seen that the decibel meter is the
scrmeqs the A.C. voltmeter with c sccle cclibrqted with the
voltcae terminqted in c 500 ohm locd.
The output meter is more commonly used in rcdio service
work lor compcrqtive recdings but if desired, A. C. Volts
cqn be converted into decibels by mecns of c conversion
chqrt. Reler to Section V-Supplementary Dctc.
5. D.C. OHMMETER.
Figures 5,6 cnd 7show the ohmmeter circuits when the range
selector switch is in positions RxI, Rxl00 and Rxl,000 respec-
I
I
I
I
ZEROADJ
t6
Figure 5 Ohmmeter Ctrcuit with Seleclor Switch in Position Bxl

tively. This switch throws in-the proper series qnd shunt
resistorsand bqtteries for eqch rcnge -so
thct -r,"" irr" i""i
leqds qre shorted,the meter will reld iul scate.
NEG.
Flgrure 6 Oh-neter Clrsult with Selector Swltch in poEition Bxl00
'-
Y
N
EG.
Figure 7 Ohrnmeter Circult with Selector Switch in posltion BxI,000
6. D.C.MITTIAMMETER
AND AMMETEN.
Iigy.t. 8c shows the circuit used when the ,,OUTpUT_A.C.-
D.C."
switchis in the "D_.C.,,position
orra-tn.;d; ""fl.it",
switch is in the 2s0 microompere po"itiott. rrrJ sri""t-il-
sistors
n5,Rl8, Rlg crnd
Rl7 ar6 of sucbvqlue thqti0;i";;_
6
?os.
t7

POS. NEG,
Figure 8a Simplilied Microcmmeler Circuil-250 microompere rcnge
qmperes flow through them cnd 200 microqmPeres flow
thr6ugh the meter toi futt scqle deflection.
Figure 8b shows the circuit used when the "OUTPUT-A.C.-
D.e." switch is in the "D.C." position and when the selector
switch is in the I0 M.A., 100-M.A. or 500 M.A. positions. It
cqn be seen thqt the resistqnce oI the shunt resistors becomes
lower qs the higher current positions qre used, thereby per-
mitting a lorgef cmount of current to flow through them, the
c*ourit flowing through the meter remcining ct 200 micro-
qmperes for fuil scqle-deIlection. The voltcae- drop cppeor-
ing-ocross the vqrious rqnges is shown opposite the current
rqnges on pcrge8.
I8
NEO.

SECTION IV
MAINTENANCE
l. The Model 215 volt-ohm-millicmmeter is q very rugged
instrument designed to tqke the weqr qnd teqr of every-dqy
service work. Nevertheless, cqre should be used c!.cinit
dropping or other excessively rough treatment.
2. Alwcys be sure of the chcracter oI the circuit to be tested
qnd see thct the selectors ore properly set before connecting.
When in doubt oI the qmounf o{-voltcAe or current preseni.
clwoys use the highest rcnge first.
3. BATTERY,NEPTACEMENT.
Fivebctteries
qremounted
insideof the cqse
to providecur-
rentfor theresistqnce
measuring
rqnges.
These
qre:
One Burgess
No.
2 Uni-cel
.. .................1.S
V.
or Evereqdy
No. 950 .....I.5
V.
or Rcy-o-vcc
No.2 ..... .. .I.SV.
or equivalent
Four Burgess No. Z Uni-cel
or Evereqdy No. 9I5... .
or Rcy-o-vcc No. 7R ..
or equivclent
1.5
V.
r.5
v.
I.5
V.
c. When it is no longer possible to bring the pointer to zero
on the RXI qnd RXI00 rcnges with the teit lecds shorted qnd
rotcting the "ZERO OHM$'knob, the single lcnge 1.5
V. bqt_
tery should be reploced
b. When it is no longer qossible to bring the pointer to zero
on the RXl,000 rqnge wilh the test leod! shoried qnd rotqt-
ing the "reRO OHMS" knob, the four smcll 1.5V. batteries
should be replcced.
c. To replace the bctteries, remove the instrument from the
ccse. This is done by removing the four screws from the
bottom oI the ccse. Slide the bdke[te bcttery retqiners out
ond.slip tbe bctteries out of the spring cfipj holding them
in _place. Insert the new bqtteries, being cqreful tliqt the
polcrity corresponds to the mcnkings on tlie bckelite bcse.
t9