Kenwood CS-1575 A User manual

CS-1575A
(DUALTRACEOSCILLOSCOPE)
INSTRUCTION MANUAL

SAFETY
Symbol in This Manual Use the ProperPowerCord
^ This symbolindicateswhereapplicablecautionary or Useonly the powercord and connectorspecified for your
otherinformationis tobe found.product.
PowerSourceUsetheProperFuse
This equipmentoperatesfrom a powersourcethatdoes To avoidfirehazard,use a fuse ofthe correcttype,
notapplymorethan 250V rms between the supplycon-
ductors or betweeneithersupplyconductor and ground. A Donot Operate inExplosiveAtmospheres
protective ground connection by way of the grounding con- To avoidexplosion, donot operatethisproduct inanex-
ductor inthe powercord is essential for safe operation.plosiveatmosphere.
GroundingtheProductDonotRemoveCoverorPanel
This equipment is grounded through the grounding conduc- To avoidpersonalinjury, donot removethecover or panel,
tor ofthe powercord. To avoid electrical shock,plug the Referservicing to qualifiedpersonnel,
powercordinto a properlywiredreceptaclebeforeconnec-
ting tothe equipmentinput or outputterminals.
CONTENTS
SAFETY 2
FEATURES 3
SPECIFICATIONS 3
A PREPARATIONFORUSE5
CONTROLSANDINDICATORS6
FRONTPANEL.6
REAR PANEL ............. 8
OPERATION9
PRELIMINARYOPERATION9
OPERATINGPROCEDURES9
TRIGGERINGOPERATION9
USE OFDUAL-H,DUAL-VANDDUAL-H,CH2POSITION10
USE OFPHASEDISPLAYANDPAHSEMEASURMENT10
WAVEFORMSETTING WITH PHASEDISPLAYANDCONTROLKNOBS11
APPLICATIONS13
APPLICATIONSOFPHASEDISPLAY13
AMPLIFIERSQUAREWAVE TEST 16
OTHERAPPLICATIONS. 20
A MAINTENANCE21
ACCESSORIES 22
2

FEATURES
1. Highsensitivity of10 mV/div or more and wideband-
width of5 MHz(-3 dB).
2. Dual-traceoperation and X-Yoperationcan be achieved
simultaneously by use of the PHASEDISPLAY switch.
3. Functions asa conventionaldual-traceoscilloscope
(DUAL-V) and stereoscope(DUAL-H).
4. ZerophaseLissajous'figure is displayed atthe same
timeduring X-Y operation,making it possible to
measurephasedifferenceaccurately throughout the
range oflowand highfrequencies.
5. Triggersource is selectedautomaticallyduringsingle
ordualtraceoperationwith the use of dualtriggering
system.
6.CHOP and ALT are interlockedwithtimebaseswitch
topermitautomaticselection.
7.X-YselectionallowsCH1amplifier tobe usedas Y axis
amplifier andCH2 amplifier asX axis amplifier inX-Y
operation mode.
8.Autofree-runsystemenables the trace tobe checked
even at no-signal.
9. The highvoltagepower for theCRTisfullyestablished
by theuseof DC-DC converter,assuringreliablesen-
sitivity and brightnessagainstvoltagefluctuation.
10. The adoption of ICs throughout the circuitryimproves
reliability.
11. Low powerconsumption (25W)for cool and reliable
operation.
SPECIFICATIONS
CATHODERAY TUBE
SWEEP
Type : 130BEB31
Sweep system :
Autofree-runsweep(free-run
Acceleration voltage : 2 kV
sweep at no-signal)
Useful measuring : 8 divxIO div(1 div= 1 cm) Sweep frequency : 10Hz-50 Hz,50 Hz-200 Hz,
VERTICAL AXIS(for both CH1andCH2)
200Hz-1 kHz,1 kHz-5 kHz,
Sensitivity :
Attenuator :
10mV/div or higher
1-3steps, 1/1to 1/300, 6
5 kHz-20 kHzand
20kHz-100 kHz
ranges, preciselyadjustable
betweenranges.
Linearity :
Fine adjustment in6 ranges.
Less than 5%
Inter-channel error is±5%.
TRIGGERING
Inputimpedance : 1 MO±3%
Source :
Approx. 30pF LINE :
Fixed to supplyfrequency.
Frequencyresponse : DUAL : Source is automaticallyselected
DC : DC to5 MHz(-3 dB),
DC to7 MHz(-6 dB)
to the waveform ofCH1or
CH2
AC : 5 Hzto5 MHz(-3 dB), CH1
:
Fixed to CH1signal.
5 Hzto7 MHz(-6 dB) CH2 :
Fixed toCH2 signal.
Risetime : 70nsec EXT :
Fixed to externalsignal.
Crosstalk : Less than -40dB(at1 kHz) Triggeringlevel :
Set by the TRIG.LEVEL switch.
Operating mode : Slope :
Positive only
CH1 : Channel 1 only,singletrace Coupling :
AConly(inclusive of EXT)
CH2 : Channel 2 only,singletrace
External triggering :
DUAL-H : Horizontaldualtrace Inputimpedance :
Approx. 1 MO, approx. 50pF
DUAL-V : Vertical dualtrace /\ Maximuminput Approx.
1 MO, approx. 50pF
X-Y : CH1 = Y axis, CH2 = X axis
voltage :
100 Vp-p or
Dual-trace selection : Automaticselection of CHOP 50
V (DC + AC peak)
andALT(Switched to CHOP at
Triggeringrange :
50 V (DC + AC peak)
about 80kHz whenSWEEP Internal
RANGEisset to10-50Hzand
(DUAL,CH1, CH2) :0.5div(50
Hz-3 MHz)
TRIG.SOURCE isin LINE,CH1,
1 div (20 Hz-5 MHz)
CH2 or EXT.Switched to ALT External (EXT) :
0.5 Vp-p(50 Hz-3 MHz)
at othersettings.)
1 Vp-p (20 Hz-5 MHz)
Phase indication : X andY are simultaneously
displayed by PHASEDISPLAY.
HORIZONTALAXIS
(CH2)
ZerophaseLissajous'figure is
Operating mode : X-Y mode is selected by
displayed at the sametime dur-
DISPLAY MODE switch.
ingX-Yoperation.
Sensitivity :
CH1: Y axis, CH2: X axis
/^Maximuminput 600
Vp-p or
Sensitivity :
Same as vertical axis (CH1)
voltage :
300 V (DC+ AC peak) Inputimpedance
: Same as vertical axis (CH1)
3

SPECIFICATIONS
Plugconfiguration Powercordandplugtype
Factory installed
instrumentfuse
Line cord
plugfuse
Parts No.for
powercord.
North American
1 20 volt/60 Hz
Rated 1 5 amp
(12ampmax;NEC)
0.7A,250V
Fast blow
AGC/3AG
None
E30-1 820-05
Universal Europe
220 volt/50 Hz
Rated16amp
0.3A,250V
T. lag
5x20mm None E30-1819-05
U.K.
240 volt/50 Hz
Rated13amp
0.3A,250V
Fast blow
6x30 mm
0.3A
TypeC
Australian
240 volt/50 Hz
Rated10amp
.0.3A,250V
Fast blow
6x30mm None E30-1821-05
North American
240 volt/60 Hz
Rated 1 5 amp
(12ampmax;NEC)
0.3A,250V
Fast blow
AGC/3AG
None
Switzerland
240 volt/50 Hz
Rated10amp
0.3A,250V
Fast blow
AGC/3AG
6x30mm
None
Fig. 1 PowerInputVoltageConfiguration
4
Frequencyresponse :
DC : - DCto 1 MHz(-3 dB),
DC to1.5MHz(-6 dB)
AC : 5 Hz to 1 MHz(-3 dB),
5 Hz to1.5MHz(-8 dB)
X-Y phasedifference : Less than 3°at50 kHz
X-Y distortionless
amplitude : More than 8 div x 8 divat
100kHz(POSITION:Center)
CALIBRATION VOLTAGE: '
0.6Vp-p ±5%
Positive squarewave of power
supplyfrequency
POWER SUPPLY
Powersupplyvoltage : AC100V/120V/220 V ± 10%,
216 V - 250 V, 50/60 Hz
Powerconsumption : Approx. 25W
DIMENSIONS
Width : 260mm (260 mm)
Height : 190 mm (214mm) .
Depth : 375 mm (440 mm)
Figures in( ) showmaximum
size.
WEIGHT: 8 kg
ACCESSORIES :
BNCcord :.2
ACcord : 1
Instruction manual : 1
Replacementfuse : 0.3A2
0.7A 2
OPTIONAL ACCESSORIES :
PC-30(attenuator probe)
Attenuation : 1/10,1/1
Inputimpedance : 10M0,22pF±10% (1/10)
1 M0,200pFor less (1/1)

PREPARATIONFORUSE
SAFETY
Beforeconnectingtheinstrument toa powersource, care-
fullyread the followinginformation,thenverifythat the
properpowercord is used andthe properlinefuse is
installed for powersource.Thespecifiedvoltageisshown
ontherearpanel.Ifthepowercordis not applied for speci-
fiedvoltage,thereisalways a certainamount of dangerfrom
electric shock.
Line voltage
This instrumentoperatesusingAC-powerinputvoltages
that100/120/220/240 V at frequenciesfrom 50Hzto
60 Hz.
Power cord
The ground wire ofthe 3-wire AC power plug places the
chassis andhousing of theoscilloscopeatearth ground. Do
notattempt to defeat the ground wireconnection or float
theoscilloscope; todosomay pose a greatsafetyhazard.
Theappropriatepowercord is supplied byan option that
is specifiedwhen the instrument is ordered.
Theoptionalpowercords are shown as follows in Fig. 1.
Linefuse
Thefuseholder is located onthe rearpanel and contains
thelinefuse.Verifythat the properfuse is installed by
replacing the linefuse.
EQUIPMENT PROTECTION
1. Neverallow a smallspot of highbrilliance to remain sta-
tionary on thescreen for morethan a fewseconds.The
screen may becomepermanentlyburned. A spot will
occur onlywhenthescope is set upfor X-Yoperation
and no signal is applied.Eitherreducetheintensity so
thespotisbarelyvisible, switch back to normalsweep
operationwhen no signalisapplied, or set up thescope
forspotblanking.
2. Nevercovertheventilatingholes on the topof theos-
cilloscope, asthis will increasetheoperatingtempera-
tureinside the case.
3. Neverapplymorethan the maximumrating to the os-
cilloscope inputs.
• ^CH1, CH2 INPUT jacks: 600Vp-por300V
(DC + ACpeak)
EXT. TRIGinput jack: 100 Vp-p or50V (DC + ACpeak)
4.Alwaysconnect a cablefrom the earth ground (GND)
jack of theoscilloscope to the chassis of theequipment
under test. Without thiscaution,theentirecurrent for
theequipmentundertest maybe drawn through the
probe clipleadsundercertaincircumstances.Suchcon-
ditionscouldalsopose a safetyhazard,which the
ground cable will prevent.
5. Operationadjacenttoequipmentwhichproducesstrong
ac magneticfieldsshould be avoidedwherepossible.
This includessuchdevices as largepowersupplies,
transformers, electric motors,etc.,thatareoften found
in an industrialenvironment.Strongmagneticshields
can exceedthepracticalCRTmagneticshieldinglimits
andresultinterference and distortion.
5

CONTROLSANDINDICATORS
FrontPanel:
©A posiTION
This controladjustsverticalpositionduring CH1orX-Y
operation. A rightturn will shift the waveformupward.
©v POSITION,X-Y<«•
This controladjustsverticalposition forCH2.It also ad-
justs horizontalpositionduring X-Y operation. A rightturn
will shift the waveformupward, ortothe rightduring X-Y
operation.
© INPUT
Inputterminal for CH1 (orY)
(4) INPUT
Inputterminal forCH2(or X).
©AC-GND-DC
Inputselector for CH1 (or Y).
®AC-GND-DC
Inputselector forCH2(or X).
®VERT.ATT
Attenuator for CH1 (or Y).Selectable m 6 rangesfrom 1/1
to1/300.Maximumsensitivity is obtainedwhen
VARIABLE (9)is turnedfully clockwise.
(DVERT.ATT
Attenuator forCH2(or XI. It functions the same as VERT
ATT® .
(DVARIABLE
Attenuator for finecontrol of CH1 (or Y).
®VARIABLE
Attenuator for finecontrol ofCH2(orX).
©CAL.0.6Vp-p
Calibrationvoltageterminal.Calibrationvoltage is0.6Vp-p
ofsquarewave of powersupplyfrequency.
©DISPLAY MODE
Operation mode selectorwith the followingfunctions.
CH1 : Only the inputwaveform to CH1 is displayed.
CH2 : Only the inputwaveform toCH2is displayed.
DUAL-H : Twoinputsignalsaredisplayed at theleft and
right.
. DUAL-V : Two inputsignals are displayed attheupand
downpositions.
X-Y : X-YoperationwhereCH1 = Y andCH2= X.
CHOP andALTare interlockedwithSOURCE
@and SWEEPRANGE © for automatic
selection. Refer to SWEEPRANGE © .
®PHASEDISPLAY
Phase indicating switch. X andY are simultaneously in-
dicated whenDISPLAY MODE © issetto DUAL-H or
DUAL-V, and zerophase Lissajous' figure is indicated at
thesametimewhenDISPLAY MODE © isat X-Y.
6

® SOURCE
Triggersignalselectorwith the followingfunctions,
LINE : Synchronized tothe powersupplyfrequency.
DUAL : Source is automaticallyselectedaccording to
thewaveform of CH1 or CH2.
GH1 : CH1 signalbecomesTriggersignal.
CH2 : CH2 signalbecomesTriggersignal.
EXT : Inputsignal of EXTTRIG @ becomesTrig-
gersignal.
® LEVEL '
This controladjustsTriggeringlevel. It determinesthestar-
ting point of sweep onthe slope of syncsignalwaveform.
®EXT.TRIG/
Inputterminal for externalTriggersignal.
©SWEEPRANGE
Horizontalsweeptimeselector. It selects in6 ranges from
10-50 Hzto20 kH-100kH. For dual-traceobservation in
therange of 10-50 Hz, both channels are switched to
CHOP at about 80kHzif SOURCE ® isset to LINE,CH1,
CH2 or EXT. In other cases, theyareswitched to ALT.
©VARIABLE
Used for fineadjustment of sweeptime.
©< • POSITION
Horizontalpositionadjuster. A right ' turn will shift
waveform tothe right. It does not functionwhenDISPLAY
MODE © isin X-Yposition. '
@). DUAL-tt CH2 POSITION
This controladjustshorizontalposition ofCH2 onlywhen
DISPLAY MODE.' © isin DUAL-Hposition. A rightturn
-will shift,waveform tothe right.
© LEDPILOT LAMP
This lamplightswhen POWER switch © is turned on.
@) POWER/INTENSITY
Functions asa powerswitch and intensitycontrol.Turning
fullycounterclockwise will turn the power OFF. Turning
clockwise will turn the power ON. Furtherturning will in-
crease the brightness of waveform.
©FOCUS
Spotfocuscontrol to obtain optimum waveform
according to brightness.
7

REAR PANEL:
® CRTcower
Used for adjustment of traceangle.Refer to "Maintenance".
© VOLTAGEPLATE
Use only the voltages and fusesspecified.
@ FUSEHOLDER
Fuse rated at0.7A is used for100V or 11 7 V operation.
For operation on220V or240V, replace it with one rated
at 0.3A.
©ACVOLTAGE SELECTOR
Beforeoperating,setthisselector to the AC powervoltage
used.
®POWERCONNECTOR
Forconnection oftheAC powercordsupplied. Usethe
supplied AC cord.
®CORDWRAP
Used to wind the powercordwhen the oscilloscope is car-
ried or stored. It alsoserves asa stand.
8

OPERATION
PRELIMINARYOPERATION
When operatingtheoscilloscope,refertopanelcontrolsandtheirfunction.Beforethepowerswitchisturnedon,setthecon-
trols asfollows.
OPERATING PROCEDURES
(1) TurnPOWER/INTENSITY @ clockwise.Thepoweris
turned toON andLEDPILOTLAMP © lights.Turn
POWER/INTENSITYfurtherclockwiseuntilthesetting
mark.indicates therighthorizontalposition.
121 Horizontaltrace will bedisplayed. When tracedoesnot
appear at thecenter of thescreen,adjust % POSI-
TION ® or< • POSITION © to center.Adjust
brightness by POWER/iNTENSlTY © . If trace is
unclear, adjustFOCUS @ .
(3) Theoscilloscopeisnowreadyformeasurements.Apply
a signal tobe measured to INPUT (3)or®. Turn
VERT.ATT (J) clockwise to obtainthedesiredsize of
waveform.
(4) Set DISPLAY MODE @ to CH1 - CH2andthe
signal to INPUT ® isdisplayed. At DUAL-Hposition,
signals to INPUTs(3)and ® appear at theleftand
right,andatDUAL-Vpositionthesignalsappearatthe
upanddownpositions.AtX-Yposition,X-Yoperation
is effectedusingsignalsto ® and ® as Y and X axis,
respectively.
15) When the signalvoltage is more.than 10mVand
waveform fails to appear onthe screen, the
oscilloscope maybe checked by feedinginputfrom
CAL 0.6Vp-p © . •
(6) When DC componentismeasured,set AC-GND-DC ©
or © toDCposition.If,inthis case, theDCcomponent
contains pluspotential,thewaveformmovesupward
and ifit containsminuspotential,thewaveformmoves
downward. The referencepoint of"0" potential is
checked atGNDposition.
Triggering operation
Toobservea:stationaryinputsignalwaveform,thesweep
circuit mustbetriggeredcorrectly.Thiscanbeaccomplished
either by inputsignal orby applying a signalwith a specific
relationship (a multiple of integer)withtheinputsignal in
terms of time tothe externaltriggerterminal.The AC
(capacitance) couplingtriggercircuitinputpermitstrigger-
ing by ACcomponentonly; DC componentintriggersignal
is cutoff. When triggersignalisabsent,thesweepcircuit
enters free-runningstate,permitting the check ofGND
level.
When a triggersignal is present,thetriggerpointcan be
determined by LEVEL © forobservationasinthenormal
triggersignal.
9

SLOPE "+" RANGE
+DIRECTION
LEVEL
- DIRECTION
Fig, i
Fig. 6 showstherelationbetweenSLOPEand LEVEL ata trig-
gerpoint.SinceSLOPE is fixed to" + ",the level of trigger
pointcan be setwithin the rangeshown in Fig.6. When the
triggeringlevelexceeds the limit, the sweepcircuitenters
free-runningstatewherethewaveform starts running.
LINE
By settingSOURCE to LINE, the inputsignal canbe syn-
chronizedwith the powersupplyfrequency.Thisfunction
makes it easy to observe a ripple of powersupplyfrequency
contained inthe signal. At thattime, LEVEL can be changed
by LEVEL © .
DUAL
The two channels are automaticallyselected for trigger
sweep and free-runsweep by means of individualsync cir-
cuits, so evenwhen the amplitude,frequency or vertical
position ofone channel is varied, it does not affect the
otherchannel. In dual-traceoperation, LEVEL © func-
tions asa leveladjuster for both CH1andCH2,and both
channels can be synchronized atthe samelevel. In single-
trace operation,only the synccircuit ofthe channelbeing
usedoperates, so sync is effectedwithoutusingSOURCE
Generally,SOURCE © issetto DUALonlywhen
waveform is monitoredwhereobservation of timerelation
between two channels isnot required, or whenobserving
single-trace waveform.
CH1, CH2
When SOURCE © issettoCH1 duringdual-trace or
single-trace operation, the sweepcircuit is drivenusing the
inputsignal of CH1 asa triggersignal. When SOURCE @
is set to CH2,thetriggersignalbecomestheinputsignal of
CH2. With SOURCEset to CH1 or CH2,triggerlevelcan be
beadjusted by TRIG. LEVEL © .
By settingSOURCE to CH1 or CH2, the timerelationbet-
ween two channelscan be observed onthe screen.
EXT
External triggering is accomplished by settingSOURCE
©to EXTposition,provided a triggersignal is applied to
EXT.TRIG © . Use LEVEL © to adjusttriggerlevel in
this case, too. Externaltriggering is usedwhen you wish to
triggerwith a signaldifferentfrom the inputsignal. It
should be noted,however,that the triggersignalmust
have a relationshipwith the inputsignal in terms of time.
Fig. 7 showsthat the sweepcircuit is driven bythe gate
signal when the gatesignal inthe burstsignal is applied to
EXT
JRJQ (jj)_ jnuS/ accuratetriggeringcan be achieved
withoutregard tothe inputsignal fedto INPUTs (3)and
-TRIGGERSIGNAL(GATESIGNAL)
-CH1 (INPUTSIGNAL)
USE OFDUAL-H,DUAL-VANDDUAL-HCH2
.POSITION,
DUAL-H
With DISPLAY MODE @ setto DUAL-H, the signal of
CH1appears atthe lefthalf ofthe scale andthe signal of
CH2 at therighthalf. At thistime,turn o POSITION ©
and both signals ofCMandCH2 will shift tothe left and
right. When DUAL-H CH2 POSITION ® is turned,only
thesignal ofCH2 will shift tothe left and right.Generally,
thestartpoint of CH1isset to theextremeleft of the scale
by <«• POSITION © andthestartpoint ofCH2 setinthe
center ofthe scale by DUAL-H CH2 POSITION ® ,
(waveform is sweptalwaysfromleft to right).Since
DUAL-H mode is used to compare" the amplitude of
waveform,SOURCE ® should be set to DUAL,asstated
in "TriggeringOperation".
DUAL-V
With DISPLAY MODE @ set to DUAL-V, the oscilloscope
functionsjust the same asa dual-traceoscilloscope. Ifitis
required to measure the timerelationbetween two signals
in DUAL-V mode, SOURCE © should besettoCH1or
CH2. Ifnot required, itmaybe set to DUAL.
USE OFPHASEDISPLAYANDPHASE
MEASUREMENT
The oscilloscope is designed for single-trace and dualtrace
operation; it displayssignals of both channels on left and
right orupand downpositions ofthe screenwhereCH1 is
displayed asY axis andCH2asX axis. The dual-trace and
X-Y observations canbe madesimultaneously by using
PHASE DISPLAY. With the PHASEDISPLAYset toONin
X-Y mode,. "zerophaseLissajous'figure(traceinclined
45°fromupperright to lowerleft of thescreen}"whenthe
same waveformwithoutphasedifference is applied toX
and Y axes is displayed. So waveforms of currentphase
difference canbe observed by comparing the Lissajous'
figure dueto signals of both channelswith"zerophase
Lissajous' figure"even onthe highfrequencybandthat
causes a phaseshift inX andY amplifiers.
10
CH2 (OUTPUT SIGNAL!
•Fig, 7

Fig. 8 shows Lissajous' figureswhen 1 kHz sinewaves of
0°, 90°and180°of phasedifference are applied toX and
Y axes. InFig.9,the frequency is changed to50kHz
where the zerophase Lissajous' figure has about 3°of
phaseshift inX andY axes ofthe oscilloscope. Whenitis
comparedwith X-Y waveform, a correctphasedifference
can be checked(refer toFig.10).
ZEROPHASELISSAJOUS'FIGURE
Fig.8
ZEROPHASELISSAJOUS'FIGURE
Fig.9
Actual phasedifference canbe obtained according toFig.
10.
WAVEFORM SETTING WITH PHASEDISPLAY
AND CONTROL KNOBS:
(In the examplesbelow, 1 kHz sinewavewith 90° phase
difference is applied toX-Y, withSWEEPRANGE setto
50-200 Hzand triggerSOURCE to DUAL.)
[EXAMPLE.1]
Fig. 11 shows the waveformwhenDISPLAY MODEisset
to DUAL-H and PHASEDISPLAY toON.Fig.12 shows the
waveformwhen the controlknobs aresetas follows:
o POSITION: Move2 divtothe left.
DUAL-H CH2 POSITION:Turn tothe right to shift the
waveform ofCH2by2 divto
theright.
SWEEPVARIABLE:Adjust by observing the screen.
Fig.11
Fig.12
11
1B
PHASEANGLE <*> = SINE~1 "X
NO PHASESHIFT INX
AND Y AMPLIFIERS OF
OSCILLOSCOPE
PHASEANGLE <j>
=SINE-1"|-- SINE~1-§-
PHASESHIFT IS PRESENT
INX ANDY AMPLIFIERS
OF OSCILLOSCOPE
Fig.10

[EXAMPLE 2]\
Fig. 13showsthewaveformwhenDISPLAY MODE isset
toDUAL-V,PHASEDISPLAYtoON,andCHIandCH2are
separatedby2 divwithy POSITION.Fig./14shows,the
waveformwhenthecontrolknobsaresetasfollows:
POSITION:Turntotherighttosetthestart point
ofwaveforminthecenterposition.
SWEEP VARIABLE:Adjustbyobservingthescreen.
Fig.14
[EXAMPLE 3]- • • . •
In Example2,if thepositionsofCH1andCH2arereversed,
thewaveformsdisplayedareasshowninFig. 1 5.Fig.16
shows thewaveformswhenPOSITION,is turned to
theleft..
Fig.15
Fig.16
12
Fig.13

APPLICATIONS
APPLICATIONS OF PHASE DISPLAY
By usingthe method shown in Fig,12,audiosystemscan
becheckedand tested. Forwaveformanalysis,refertoFig.
20. Inthewaveformsshown in Fig.20,DUAL-H mode and
zerophase Lissajous' figure are simultaneouslydisplayed
forconvenience. It should be notedthat the zerophase
Lissajous' figureisdisplayedonlywhenPHASEDISPLAYis
set toONin X-Y mode.
AdjustmentofHeadAzimuthofTapeDeck
Use a standardtape(400 Hzor 315Hz) andsetthe
oscilloscope to 1/10sensitivity(Fig.17).Sincethe output
frequencyresponse ofa tapedeck is30Hzto20 kHz,
there isno phaseshift in 400 Hzor 315Hz.Adjust the
headazimuthsothatthephasedifferenceinthe Lissajous'
figureiseliminated.
Test ofOutputAmplifier
Applytheoutputs ofa sinewavesignalgenerator to both
channels of theamplifierunder test. Connecttheamplifier
output tothe oscilloscopeinputusing the same dummy
load and adjust the sensitivity ofthe oscilloscope so that
optimum amplitude is obtainedaccording to the output of
theamplifier(Fig.18).Fortestingthesquarewaveform of
theamplifier,refer to theparagraphbelow.
13
Fig. 17
Audiosignalgenerator
AUX
Output amplifier
Dummy
load
Dummyload
Fig. 18
> DUAL
DUAL-H

Test ofPropagation Characteristic ofListeningRoom
In a listening room the sound,from the speaker is some-
times hearlouder.Thishappenswhencertainfrequencies
of the soundare.resonatedwith the naturalvibration of
listening room,
The resonancefrequency canbe detected by using the
oscilloscope. Connect the output ofa sinewavesignal
generator totheAUX input ofa pre-mainamplifier and
place a highoutputdynamicmicrophone atthe listening
position.Connect the output ofthe microphone toCH1
and a part of theoutput of thesignalgenerator to CH2 to
compare the levels. Adjust the volume ofthe amplifier
observingtheoscilloscopeandincreasethefrequencyfrom
about 50Hzto about 20 kHzgraduallywiththeoutput of
the signalgeneratormaintainedconstant. If,at thistime/
the listening room is resonated, the amplitude onthe
screen becomesmaximumattheresonancepoint.Thisfre-
quencyisabout100 Hzto1 kHz(Fig. 19).
Audiosignalgenerator
Speaker
Pre-mainamplifier
Speaker
Dynamic microphone
.DUAL
•DUAL-H
Fig. 19
14
AUX

Ho. Wave form Judgement
Trouble
Remarks
1
Nophaseshift. No
amplitudedistortion.
No distortionbet-
ween channels.
The samesignalisapplied
toCH1andCH2.
2
180° outof phase.
Noamplitudedistor-
tion.
*Incorrectinput con-
nection(signaland
earthconnectedin
reverse.
*Incorrectcircuitwir-
ing.
Locate the cause oftrou-
blereferringtothenormal
waveformshowninNo.1.
3
Phase shift.
Noamplitudedistor-
tion.
Improperazimuthad-
justment.
4
Nophaseshift.
Amplitudedistortion
(CH1amplitudeis
narrow. *Outputsnotbalanc-
ed.
*ATTand VARIABLE
ofoscilloscopenot
balanced.
The inclinationofzero
phase Lissajous' figureis
always 45°.Iftheinclina-
tion ofX-Yisthesameas
that ofthisfigure,thereis
noamplitudedistortionin
bothchannels,ifitis
smaller, CH1amplitude
becomes narrow.
5
Nophaseshift.
Amplitudedistortion
(CH2amplitudeis
narrow.
*Outputsnotbalanc-
ed.
*ATTand VARIABLE
ofoscilloscopenot
balanced.
The inclinationofzero
phase Lissajous' figureis
always 45°.Iftheinclina-
tion ofX-Yisthesameas
that ofthisfigure,thereis
noamplitudedistortionin
bothchannels,ifitis
smaller, CH1amplitude
becomes narrow.
6
Nophaseshift.
Noamplitudedistor-
tion between chan-
nels.
Stylus pressure,inside
forcecanceler,over-
hangandarmheightof
record playerarenot
properlyadjusted,or
stylus isdirty.
Compare zerophase
Lissajous' figure with X-Y
tolocatethe cause of
distortion.Checkingthe
sine waveisnotsuffi-
cient.
7
•NosignalinCH1.
Disconnection orpoor
connection ofsignal.
8 NosignalinCH2.
Ifthereisnosignalin
CH2, zerophase Lissa-
jous' figurebecomesa
spot.
Fig. 20Waveform analysis
Note:
ZerophaseLissajous'figure canbe observedonlywith
PHASE DISPLAYset toONin X-Y mode. Thus,thewave-
formsshownabovedifferfromthoseactuallyobtained on
thescreen.
1b

AMPLIFIER SQUARE WAVE TEST
Introduction
Asquarewavegeneratorandoscilloscopecan be used to
displayvarioustypes of distortionpresent in electric cir-
cuits. A squarewave ofa givenfrequencycontains a large
number ofodd harmonics of thatfrequency. Ifa 500 Hz
squarewave is injectedinto a circuit,frequencycom-
ponents of1.5 kHz, 2.5 kHz, 3.5 kHzarealsoprovided.
Since transistorsarenon-linear, it isdifficult to amplifyand
reproduce a squarewavewhich is identical tothe input
signal.
Junction capacitance,straycapacitances as well as nar-
rowbanddevicesandtransformerresponsearethefactors
which preventfaithfulresponse ofa squarewavesignal. A
well-designedamplifiercanminimizethedistortioncaused
bytheselimitations.Poorlydesigned or defective
amplifierscanintroducedistortion to thepointwheretheir
performance is unsatisfactory. As statedabove, a square
wave contains a largenumber ofodd harmonics. By injec-
tion ofa 500Hz sinewaveinto an amplifier, wecan
evaluate amplifierresponse at 500 Hz only, butby injec-
ting a squarewave of thesamefrequency we candeter-
mine howthe amplifierwouldresponse to inputsignals
from500 Hzupto the15th or 21stharmonic.
The need for squarewaveevaluationbecomesapparent if
we realizethatsomeaudioamplifiers will be requiredduring
normaluse to passsimultaneously a largenumber of dif-
ferentfrequencies. With a squarewave, we canevaluate
thequality of input and output characteristics ofa signal
containing a largenumber of frequencycomponentssuch
as complexwaveforms of musicalinstruments or voices.
The squarewave output ofthe signalgeneratormust be
extremely flat.Theoscilloscopeverticalinputshould be set
to DCasit will introducetheleastdistortion,especially at
lowfrequencies.Because ofthe harmoniccontent ofthe
squarewave,distortion will occurbeforetheupperend of
theamplifierbandpass. It should be notedthattheactual
responsecheck of anamplifiershould be madeusing a sine
wave signal.Thisisespeciallyimportant in anlimitedband-
pass amplifiersuch asa voiceamplifier.Thesquarewave
signal provides a quickcheck of amplifierperformanceand
will giveanestimate of overallamplifierquality.Thesquare
wave will alsorevealsomedeficiencies not readily ap-
parentwhenusing a sinewavesignal.Whether a sinewave
orsquarewaveisusedfortestingtheamplifier, it is impor-
tantthatthemanufacturer'sspecifications on theamplifier
beknowninorder to make a betterjudgement of itsperfor-
mance.
Testing Procedure (refer to Fig. 21)
(1) Connect the output ofthe squarewavegenerator to
theinput of theamplifierbeingtested.
(2) ConnecttheCH2 of theoscilloscope to the output of
theamplifier.
(3) If the DC component of theamplifier output is low,set
the AC-GND-DC switch toDC position to allow both the
ACand DC components to beviewed.However,the AC
positionmaybeusedtoobservetheACcomponentonly,
though this will reducetheaudiofrequency of contents
of less than 5 Hz.
(4) Adjusttheverticalgaincontrols fora convenientviewing
height.
(5) Adjustthesweeptimecontrols for one cycle of square
wave display on thescreen.
Square wavegenerator
INPUT Amplifiercircuit
beingtested
OUTPUT
Adjust sweep
speed for1
cycle display.
Fig. 21Equipmentset-upforsquarewavetestingofamplifiers
16
AdjustVERTGAIN
forconvenient *
viewingheight.

Analysis ofWaveforms
The shortrisetimewhichoccurs atthe beginning ofthe
half-cycle is created bythe in-phase sumofthe medium
andhighfrequencysinewavecomponents,
The sameholdstrue for the drop time.
The reduction in highfrequencycomponentsshouldpro-
duce a rounding of thesquarecorners at allfourpoints of
onesquarewave cycle I see Fig.22).
Distortion canbe classifiedinto the followingthree
categories:
1. The first is frequencydistortion and refers tothe
change inthe amplitude ofa complexwaveform. Sn
otherwords, the introduction inan amplifiercircuit of
resonantnetwork or selectivefilterscreated by combi-
nation of relativecomponents will createpeaks or dips
in an otherwiseflatfrequencyresponsecurve.
2. The second is non-lineardistortion and refers toa
change in waveshapeproduced by application ofthe
waveshape to non-linearelementssuchastransistors,
anironcoretransformer ora clippernetwork.
3. Thethird is delay or phasedistortion,which is distor-
tionproduced bya shift in phasebetweensomecom-
ponents ofa complexwaveform.
Fig. 22Squarewaveresponse with highfrequency
loss
As a rule of thumb, it can be safelysaidthat a squarewave
can be used to revealresponse and phaserelationships up
to the 15th or 20th odd harmonic orupto approximately
40times the fundamental ofthe squarewave. Itis seen
thatwide-bandcircuitry will require at leasttwofrequency
check points to properlyanalyzetheentirebandpass.Inthe
case illustrated byFig.23,a 100Hz squarewave will
encompasscomponents upto about 4 kHz.
Toanalyzeabove 4 kHz and beyond 10,000 Hz,a 1 kHz
squarewaveshould be used. Now,the regionbetween
100 Hzand 4000 Hzin Fig. 23 shows a risefrom poor
low-frequency(100 Hzto1 kHz) response toa flattening
outfrom beyond 1000and 4000 Hz. Therefore, wecan
expect that the higherfrequencycomponents inthe
100 Hz squarewave will be relativelynormal in amplitude
andphase but thatthelow-frequencycomponents"B" in
this samesquarewave will be modified bythe poor low-
frequencyresponse of thisamplifier(seeFig.24).
Fig. 23Responsecurveofamplifier with poor
lowandhighends
In actualpractice, a change in amplitude ofa squarewave
component is usuallycaused bya frequencyselectivenet-
workwhichincludescapacity,inductance or both. The
presence oftheC orL introduces a difference in phase
anglebetweencomponents,creatingphasedistortion or
delaydistortion.Therefore, in squarewavetesting of prac-
tical circuitry, we usuallyfindthat the distorted . square
wave' includes ' a combination of amplitude and phase
distortions. Ina typicalwidebandamplifier, a squarewave
check revealsmanydistortion characteristics of thecircuit.
The response ofan amplifierisindicated in Fig.23,reveal-
ing poor low frequencyresponsealongwithovercompen-
sated highfrequencyboost. The response of100Hz
squarewaveapplied tothe amplifier will appear asin Fig.
24A. The figureindicatessatisfactory medium frequency
response(approximately 1 kHzto2 kHz) but shows poor
lowfrequencyresponse.Next, a 1 kHz squarewave ap-
plied to theinput of theamplifier will appearas in Fig.24B.
This figuredisplays good frequencyresponse in theregion
of1000 to 4000 Hzbut reveals a sharprise at thetop of
theleadingedge ofthe squarewavebecause of over-
compensation at frequencies of morethan 10 kHz.
100Hz
square
wave
1 kHz
square
wave
Fig. 24Resultant100Hzand1 kHzsquare
waves from amplifierinFig.23
17
RESPONSE

If the amplifierweresuch asto onlydepress thelow fre-
quencycomponents in thesquarewave, a curvesimilar to
Fig. 25 would be obtained.However,-reduction in
amplitude ofthe components is usuallycaused bya reac-
tive element,causing, in turn, .a phaseshift .ofthe com-
ponents,.producing the tilt as shown in Fig. 24A. Fig. 26
reveals a graphicaldevelopment ofa similarlytiltedsquare
wave. The tilt isseen tobe caused by thestronginfluence
ofthephase-shifted3rdharmonic. It alsobecomesevident
thatveryslightshifts in phasearequicklyshown upby tilt
inthesquarewave.
Fig. 25Reductionofsquarewavefundamental
frequencycomponentina tunedcircuit
FX3 outofphase(lead)
Fig. 26Squarewave tilt resulting from 3rd
harmonicphaseshift
Fig. 27 indicatesthe tilt in squarewaveproduced bya 10°
phaseshift ofa low frequencyelement ina leadingdirec-
tion.Fig. 28 indicates a 10°phase shift ina lowfrequency
component ina laggingdirection.The tilts areopposite in
thetwo cases because of thedifference in polarity ofthe
phaseangle inthetwo cases as can be checked through
algebraicaddition of components.
Fig. 29 indicates low frequencycomponentswhichhave
beenreduced in amplitude and shifted in phase. It will be
notedthattheseexamples of lowfrequencydistortionare
characterized by change in shape of theflatportion of the
squarewave.
Fig. 24B shows a highfrequencyovershootproduced by
risingamplifierresponse at thehighfrequencies.
It shouldagain be notedthatthisovershootmakesitself
evident at the topof theleadingedge of thesquarewave.
Thesharp rise of theleadingedgeiscreated by thesum of
a largenumber of harmoniccomponents. Ifan abnormal
rise in amplifierresponseoccurs at highfrequencies, the
highfrequencycomponents inthe squarewave will be
amplifiedlargerthantheothercomponents,creating a high
algebraicsumalongtheleadingedge.
Fig, 29Lowfrequency componentloss and
phaseshift
18
FX r
FX1 outof phase (lead)
Fig. 27 Tilt resulting
fromphaseshift of
fundamental frequencyina leadingdirection
FX1 outofphase(lag)
FXi-
Fig. 28 Tilt resulting
fromphaseshift of
fundamentalfrequency ina laggingdirection
FX1 outof phaseflag)

Fig. 30 indicateshighfrequencyboost inan amplifier
accompanied bya lightlydamped"shock"transient.
In this case, whenthesuddentransitioninthesquarewave,
potentialfrom a sharplyrising,relativelyhighfrequency
voltage, toa levelvalue of lowfrequencyvoltage,provided
that the energy for oscillation inthe resonant,network in
theamplifier is reasonablydamped,then a. single cycle
transient oscillation maybe produced as illustrated - inFig.
31.. Fig. 32 summarizes the precedingexplanation and
serves as a handyreference.
Fig. 30. Effect of
. high frequency boost and poor damping
Frequency distortion, (amplitude reduc-
tion oflowfrequencycomponent).No
phase shift.
Low frequencyboost,(accentuatedfun-
damental)
C. High frequency loss. Nophaseshift
D.Lowfrequencyphaseshift
E. Lowfrequency loss andphaseshift
F. High frequency loss andlowfrequency
phase shift
G. High frequency loss andphaseshift H.Dampedoscillation I.Lowfrequencyphaseshift(trace
thickenedbyhum-voltage)
Fig. 32Summaryofwaveform analysis forsquarewavetestingofamplifiers
19
Fig. 31 Effect of
high frequency boost and good damping

OTHER APPLICATIONS ..."
Amplifier PhaseShift Measurement. -
In thesquarewavetestingsection of thismanual,square
wave distortion is explained in terms of phaseshift of the
signal components . whichcomprise the squarewave.
These phaseshiftscan be verifieddirectly by providing a
sine wave input signal tothe amplifierandobserving the
phase of output signalwithrespecttothe input signal.Inall
amplifiers, a phaseshiftisalwaysassociatedwith a change
in amplitude-response. For example, atthe —3 dB
response point, a phaseshift of46° occurs.
Fig. 33 illustrates a method of determiningamplifierphase
shift directly. In this case, the measurements are being
made at approximately 5000 Hz. The input signal is used
as a'reference andis applied-totheChannel 1 input. The
VARIABLE controlisadjustedasrequired to provide a com-
plete cycle ofthe input waveformdisplayed on8 div
horizontally,,whilethewaveformheightissetto 2 div.The
8 div.display,represents 360° atthe displayedfrequency
and a centimeterrepresents 45°of thewaveform.
The VER.ATTcontrols, of Channel 2 areadjusted asre-
quired to produce a peak-to-peakwaveform of2 div. The
Channel 2 POSITIONcontrol is thenadjusted so that the
Channel 2 waveform is displayed onthe samehorizontal
axis astheChannel 1 waveform.Thedistancebetweenthe
twowaveformsthenrepresents the phaseshiftbetween
thetwowaveforms.Inthis case, thezerocrossoverpoints
of thetwo waveforms are compared. The illustration
shows a phasedifference of1 div whichmeans a phase
shift of45°.
Fig. 33Measuring amplifierphaseshift
Stereo AmplifierServicing
Anotherconvenient useof dual-traceoscilloscope isin
trouble-shooting of stereoamplifiers. If identicalamplifiers
are usedandthe output of oneisweak,distorted or other-
wise abnormal, the dual-traceoscilloscopecan be effec-
tively used to localizethedefective state. With anidentical
signal applied tothe inputs of both amplifiers, a side-by-
side comparison of both unitscan be made by progressive-
ly samplingidenticalsignalpoints in both amplifiers.
When the defective or malfunctioningstage has been
located, it can be immediatelyobservedandanalyzed.
20
Adjust asrequired
forcomplete cycle indiv.
5-20kHz
AF signal
generator INPUT Audioamplifier
OUTPUT
LOAD