Trio CS-1566A User manual

TRIGGEREDSWEEPOSCILLOSCOPE
HIGH STABILITY
CS-1566A
DUAL TRACEOSCILLOSCOPE
INSTRUCTION MANUAL
TRIO

FEATURES
*Vertical axis with widebandwidth(20MHz,—3
dB) and high sensitivity(5mV/div,1 div= 1
cm).
*Distortion-freedisplayofsignalsupto20MHz
onthe full areaofCRTscreen.
*HighsensitivityCRT(rectangular with internal
graticule) with excellentbeampermeabilityhas
sufficientbrightnessformeasurementsof
high-speedpulsesof high frequencies.
*The high voltagepowerforCRTaswellthe
powerforothercircuitsis fully stabilized
because oftheuseof DC-DC converter,thusthe
sensitivityandbrightnessarecompletelyfree
from effectsofvoltagevariations.
*X-Yoperationispossible with CH2amplifier
used asX axis. Thehorizontal axis sensitivityis
as high as5mV/div.
*ALTand CHOP operationsfordual-trace
observation.
*The time baseswitchallowschangeover
betweenV (vertical)andH (horizontal)of VIDEO
sync separatorcircuit,automaticallyand
electronically.
*INT,CH1,CH2, LINE andEXTcanbe
individuallysynchronizedforselectionofdesired
syhc signals.
*AtAUTO position of TRIG LEVEL, itispossible
tocheckthebrightnessatno-signal time andto
adjust triggering levelof input waveforms.
*The adoption ofICs throughout assures high
performanceandimprovedreliability.
Page
FEATURES 2
SPECIFICATIONS 3
CONTROLS ON PANELS 5
FrontPanel6
Rear Panel8
OPERATION 8
PreliminaryOperation8
OperatingProcedures9
MeasurementofPulseRising(Falling)Time9
APPLICATIONS 10
Dual-traceApplications10
Single-channel Applications19
FM ReceiverAdjustments22
X-Y OperationApplications22
AmplifierSquareWave Test 24
PRECAUTIONS 29
MAINTENANCE AND ADJUSTMENT 29
Maintenance29
Adjustment30
SCHEMATIC DIAGRAM33
CONTENTS
2

SPECIFICATIONS
Cathode RayTube
Type:
C5S106P31B
Acceleration voltage:
2 kV
Scale:
8 divx10div(1div= 9.5mm)
Vertical Amplifier(forBothCHIandCH2)
DeflectionFactor:
5 mV/divto20V/div±5%
Attenuator:
5 mV/divto20V/div.1-2-5sequence
Precisely adjustableinall12ranges.
Sensitivity errorbetweenrangesis±5%.
Input impedance:
1 Mil ±2%
Inputcapacitance:
Approx.27pF
Frequency response:
DC DCto20MHz (less than-3dB)
[5 mV/div~ 10V/div]
AC 2 Hzto20MHz (less than-3dB)
[5 mV/div~ 10V/div]
Risetime:
Less than17.5 nsec.
Overshoot:
Less than3%(at100kHzsquare wave)
Cross-talk:
ALT Less than—60dB
CHOP Less than-50dB
Operatingmodes:
CH1 CH1only
CH2 CH2only
ALT 2-channel with ALT(alternatesweep)
CHOP 2-channel with CHOP
ADD 2-channelalgebraicsum (CH1 + CH2)
CHOP frequency:
Approx.200kHz
Maximum inputvoltage:
600 Vp-por300V(DC+ ACpeak)
Invertpolarity:
CH2 only
Sweep Circuit
Sweep system:
Triggeringsweepandautosweep(free-running
sweep atno-signaltime)
Sweep time:
0.5Ms/divto.5s/div±5%andX-Y.1-2-5
sequence
Fine adjustmentinall19ranges
Magnification:
10 times±5% (PULL x 10MAG).
Linearity:
Better than3%(2/zs/divto0.5s/div)
Better than5%(0.5^s/divto1 ^s/div)
Better than10%( x 10MAG)
Triggering
Source: ••-•••:.-y^
INT. CH1.CH2. LINE, EXT
Slope:
NORM Positiveandnegative
VIDEO Positiveandnegative (LINE and
FRAME automaticallyselectedby.
SWEEP TIME/DIV)
LINE (TV-line): 0.5 ns/Div to50
Ats/div
FRAME (TV-Frame): 0.1ms/divto
0.5s/div
Sensitivity:
Trigger
Type
Bandwidth
Minimum Sync Voltage
Trigger
Type
Bandwidth INT
EXT
NOR 50Hz~15MHz
20Hz~20MHz
0.5div
1.0div
0.5Vp-p
1.0Vp-p
AUTO
50Hz~15MHz
20Hz~20MHz
0.5div
1.0div
0.5Vp-p
1.0Vp-p
VIDEO VIDEO
signal 1.0div 1.0Vp-p
External triggeringinputvoltage:
50V (DC+ ACpeak)
HorizontalAmplifier(CH2input)
Operatingmodes:(Exceptx 10MAG)
X-Y modeisselectedby SWEEP TIME/DIV.
CH1: Y axis
CH2: X axis
DeflectionFactor:
Same asCH1(5mV/divto20V/div±5%)
Frequency response:
DC DCto2 MHz (less than-3dB)
AC 2 Hzto2 MHz (less than-3dB)
Inputimpedance:
Same asCH1(1MS2±2%)
Inputcapacitance:
Same asCH1Approx.27pF
X-Y phasedifference:
Less than3°at70kHz
3

CalibratingVoltage
0.1V±3%(atreferencelevelOV)
1 kHz±3%(squarewave,positive)
IntensityModulation
Input voltage:
TTL level
Input impedance:
15 ktt±20%
Bandwidth:
DC to5 MHz
Maximum input voltage:
50V (DC+ ACpeak)
Trace Rotation
Trace angleisadjustablebypanelsurfacead
justor.
PowerRequirements
Power supplyvoltage:
100/120/220/240V ±10%.50/60Hz
Power consumption:
47W
Dimensions
Width.
260 mm(277mm)
Height:
190 mm(204mm)
Depth:
328 mm(393mm)
Figures in( ) showmaximum sizes.
Weight:
8.4kg
Accessories
Probe (PC-22) 2
Damping:1/10
Input impedance:10MQ
Input capacitance: Less than18pF
Instructionmanual1
Replacement fuse:
0.5A2
0.8Ao
4

CONTROLSONPANELS
FRONTPANEL
Fig.1
REAR PANEL
Fig.2
5

FRONT PANEL
1. ^ POSITION
Vertical position adjustmentforChannel1 trace.
Becomes vertical position adjustmentwhen
SWEEP TIME/DIVswitch(21)isintheX-Yposi-
tion (X-Yoperation).
2. INPUT
Vertical input terminalforCH1(orinX-Ymode).
3. AC-GND-DC
AC: BlocksDCcomponentof input signal.
GND:Openssignalpathand ground input to
verticalamplifier.Thisprovidesa zero-
signalbaseline,the position ofwhichcan
beusedasa referencewhen performing
DC measurement.
DC: Direct input ofACandDCcomponentof
input signal.
4.VOLTS/DIV
VerticalattenuatorforChannel1 whichprovides
stepadjustmentofverticalsensitivity.Vertical sen-
sitivityiscalibratedin12steps from 5 mVto20
voltsperdivwhen VARIABLE control (5)issetto
CAL position.This control adjustsvertical sen-
sitivitywhenthe SWEEP TIME/DIVswitch(21)is
intheX-Y position (X-Yoperation).
5.VARIABLE
Verticalattenuatoradjustmentprovidesfine control
ofverticalsensitivity.Intheextremeclockwise
(CAL) position,theverticalattenuatoriscalibrated.
This control becomesthefineverticalgain control
whenthe SWEEP TIME/DINswitch(21)isinthe
X-Y position.
6.MODE
Five-positionleverswitch;selectsthebasic
operatingmodesoftheoscilloscope.
CH 1:Onlythe input signaltoChannel 1 isdis-
playedasa singletrace.
CH 2:Onlythe input signaltoChannel2 isdis-
playedasa singletrace.
ALT: Dual-traceoperation,inwhichsweep
alternatelydisplaysChannel1,then
Channel 2, input signal.Recommended
forsweeptimesof0.5ms/divto0.5/is/
div.
CHOP: Dual-traceoperationinwhichsweepis
choppedatapproximate200kHzrateand
switchedbetweenChannel1 andChannel
2 traces.Recommendedforsweeptimes
of0.5s/divto1 ms/div.
ADD:Thewaveforms from Channel1 and
Channel 2 inputsareaddedandthesumis
displayedasa singletrace.Whenthe
Channel 2 POSITION control ispulled
(PULL INVERT), thewaveform from
Channel 2 issubtracted from theChannel
1 waveformandthedifferenceisdis-
playedasa singletrace.
7.VOLTS/DIV
VerticalattenuatorforChannel2 whichprovides
coarse adjustmentofverticalsensitivity.Vertical
sensitivityiscalibratedin12steps from 5 mVto20
voltsperdivwhen VARIABLE control (8)issetto
theCALposition.
8.VARIABLE
Verticalattenuatoradjustmentprovidesfine control
ofverticalsensitivity.Intheextremeclockwise
(CAL) position,theverticalattenuatoriscalibrated.
9.AC-GND-DC
AC: BlocksDCcomponentof input signal.
GND: Openssignalpathandgrounds input to
verticalamplifier.Thisprovidesa zero-
signalbaseline,the position ofwhichcan
beusedasa referencewhen performing
DC measurements.
DC: Direct input ofACandDCcomponentof
input signal.
10.INPUT
Vertical input terminalforCH2orX input terminal
forX-Yoperation.
11. y POSITION,X-Y<+, PULL
INVERT
Vertical position adjustmentforChannel2 trace.
Becomes horizontal position adjustmentwhen
SWEEP TIME/DIVswitch(21)isintheX-Yposi-
tion (X-Yoperation).
Whentheknobispulled (PULL INVERT), theCH2
polarity isinverted.
12. POWERLAMP
Glows whenoscilloscopeisturnedon.
13. POWER
Power ON/OFF switch.ThepowerisONwhenthe
knobissetto right.
14.INTENSITY
Adjuststhebrightnessofspotsandwaveformsfor
easy viewing.Whentamedtothe left waveform
will disappear.
6

15. FOCUS
Spotfocus control to obtain optimum waveform
accordingtobrightness.
16.EXTTRIG
External trigger terminal.Forexternaltriggering,
set SOURCE (17)toEXTandapplyexternal
triggering voltage.
17. SOURCE
Five-positionleverswitchselects triggering source
forsweep.
INT: InCH2 mode,Channel2 signalbecomes
trigger. InCH1,ALT, CHOP, andADD
mode,Channel1 signalbecomes trigger.
CH 1:Channel1 signalbecomes trigger inail
modes.
CH 2:Channel2 signalbecomes trigger inall
modes.
LINE: Linevoltagebecomes trigger.
EXT: Signalappliedat EXT TRIG jackbecomes
trigger.
18.SYNC
Four-positionleverswitch with the following
positions:
SLOPE: The SLOPE positionsareusedforviewing
allwaveformsexcepttelevisioncomposite
videosignals.
(-+-):Sweepis triggered onpositive-
going slopeofwaveform.
( —): Sweepis triggered onnegative-
going slopeofwaveform.
SYNC SWITCH
VIDEO ( + )
VIDEO ( —)
VIDEO: Inthe VIDEO positions,thesyncpulsesof
a compositevideosignalareusedto
trigger thesweep;theverticalsyncpulses
(frame) areautomaticallyselectedfor
sweep timesof0.5s/divto0.1ms/div,
andhorizontalsyncpulses(line)are
automaticallyselectedforsweeptimesof
50 /xs/divto0.5/ns/div.
( + ): Sweepis triggered onpositive-
going syncpulse.
( —): Sweepis triggered onnegative-
going syncpulse.
19. LEVEL, PULL AUTO
Sync leveladjustmentdeterminespointson
waveformslopewheresweepstarts;( —) equals
mostnegative point of triggering and(+)equals
mostpositive point oftriggering.
PULL AUTO:
Push-pullswitchselectsautomatic triggering when
pulledout (PULL AUTO). Whenautomatic trigger-
ing,a sweepisgeneratedeven without an input
signal.
20.««•POSITION, PULL X10MAG
Rotationadjustshorizontal position oftraces (both
traces whenoperatedinthedualtracemode).
PULL X10MAG:
Push-pullswitchselectsX10magnificationwhen
pulledout (PULL X10MAG);normalwhenpushed
in.
21. SWEEP TIME/DIV
Horizontalcoarsesweep time selector.Selects
calibratedsweeptimesof0.5^s/div(microsecond
perdivision)to0.5s/divin19stepswhen
VARIABLE control (22)issettotheCAL position
(fullyclockwise).IntheX-Yposition,thisswitch
disables theinternalsweepgeneratorandpermits
theCH2 input toprovidehorizontaldeflection(X-Y
operation).TheChannel1 input signalproduces
verticaldeflection(Y axis) andtheChannel2 input
signalproduceshorizontaldeflection(X axis).
22. VARIABLE
Fine sweep time adjustment.Intheextreme
clockwise (CAL) position thesweep time is
calibrated.
23. CAL1 kHz,0.1Vp-p
Provides calibrated1 kHz,0.1 volt peak-to-peak
square wave input signal.Thisisusedforcalibra-
tion oftheverticalamplifierattenuatorsandto
check thefrequencycompensationadjustmentof
theprobesused with theoscilloscope.
7
Fig. 3

24.GND
Groundterminalfortheoscilloscope.
25.TRACE ROTATION
Used toadjustthepositionofhorizontaltrace.
26. HANDLE
This handlealso serves asa standoftheos-
cilloscope.
REAR PANEL
27. AC VOLTAGE SELECTOR
Plug typeACvoltageselectortooperatetheos-
cilloscope onspecificpowersupplyvoltage,
100/117/220/240V.
28.FUSE HOLDER
Fuse ratedat1Ashouldbeusedfor100/117V
operation.Foroperationon220/240V,besureto
use a 0.5A fuse.
29. POWERCONNECTOR
For connectionofthesuppliedACpowercord.
30.Z AXISINPUT
Intensitymodulationterminal.TTLlogic-
compatible,highlogicincreasebrightnesslowlogic
decrease brightness.
31. CORD REEL
Windpowercordwhentheoscilloscopeistobe
carried orstored. They also serve asa standwhen
theoscilloscopeisusedin upright position.
OPERATION
PRELIMINARY OPERATION
When operatingthisoscilloscope,refertopanelcontrolsandtheirfunctions.Whenstartingthisoscilloscope
set initially,settheoperatingcontrolsasfollowsandthesetmaybeturnedonsafely.
Fig. 4
8

OPERATING PROCEDURES
1. Selectthepositionofthepowervoltage selec-
torplugasindicatedbythearrowmarks.Then
insertthesuppliedpowercordtothepower
connector.
2. Turn POWER/SCALE ILLUM(13)clockwise.
The poweristurnedtoONand POWER lamp
(12) lights.
3. Horizontal axis willbedisplayed.Whentrace
does notappearatthecenterofthe screen,
adjust^ POSITION (1)and POSITION (20).
Adjustbrightness with INTENSITY (14).If
trace isunclear,adjust FOCUS (15).
4. Theoscilloscopeisnowreadyformeasure-
ment.Formeasurement,proceedasfollows:
Applysignalvoltagestothe INPUT terminals
(2), (10).Then turn VOLTS/DIV (4)clockwise
until thewaveformiscorrectlydisplayedon
thescope.BysettingMODE(6)and SOURCE
(17) toCH1,theCH1 input signaltothe
INPUT terminal(2)willappear.Similarly,by
settingMODEand SOURCE toCH2,thenthe
input signaltotheCH2terminal(10)will
appear, atALTor CHOP position,two
waveforms (CH1andCH2)willappearonthe
scope. With SOURCE (17)settoCH1,the
CH1 input signal from the INPUT terminal(2)
is fedtothetriggercircuitwheretheCH1
signal istriggered.Similarly,when SOURCE is
set toCH2,theCH2signalistriggered.
MEASUREMENTS OF PULSE RISING (FALLING) TIME
The scales 10%and90%ontheCRTscreenare
used foraccuratemeasurementsofpulserising
(falling)time.Tomeasurepulserisingtime,
proceedasfollows:
1. Witha pulsesignalappliedtothe input
terminal,adjust VOLTS/DIV (4)[7]and
VARIABLE (5)[8]sothatthepulseamplitude
is settothe0 and100% scales.
2. Turn SWEEP TIME/DIV (21)tomagnifythe
rising portion ofthewaveformaslargeas
possible [VARIABLE (22)shouldbesettoCAL
position].
3. Adjust POSITION (20)tosetthe
waveforms at10%and90%tothevertical
center scale respectively,thenmeasure T1 and
T2 usingthehorizontalcenter scale. Thepulse
rising(falling)timeisT1+ T2.
Use eithermethodforeasierobservation.
AtADDposition,algebraicsumofCH1and
CH2 isobtained.When PULL INVERT (11)
knobispulled,theCH2signalinreverse
polarityisaddedtotheCH1signalinreverse
polarityisaddedtotheCH1signalandthe
algebraic differencebetweenCH1andCH2is
displayed (SUB).
5. Whenthesignalvoltageismorethan5 mV
andwaveformfailstoappearonthe screen,
theoscilloscopemaybecheckedbyfeedingin-
put from CAL1 kHz,0.1Vp-p(23). Since
calibrationvoltageis1 Vp-p,thewaveform
becomes 5 divhighatthe20mV/divposition.
6. Bypushing TRIG LEVEL (20),thefree-running
autofunctionisreleased.Thewaveformdis-
appears whentheknobisturnedclockwise,
andappearsagainwhenitisreturnedtoitsap-
proximatemiddlepositionofit. Sync phaseis
also adjustableinthis case. Thewaveformwill
againdisappearwhentheknobisturned
counterclockwise from themiddleposition.
7. WhenDCcomponentismeasured,set
AC-GND-DC (3)or(9)toDCposition.If,in
this case, theDCcomponentcontainsplus
"+ " potential,thewaveformmovesupward
andifitcontainsminus" —"potential,the
waveformmovesdownward.
The reference point of"0"potentialcanbe
checked atGNDposition.
9

APPLICATIONS
DUAL-TRACE APPLICATIONS
Introduction:
Themostobviousandyetthemostusefulfeature
ofthedual-traceoscilloscopeis that ithasthe
capabilityforsimultaneouslyviewingtwo
waveforms that arefrequencyorphase-related,or
that havea commonsynchronizingvoltage, such as
in digital circuitry.Simultaneouslyviewingofinput
andits output isaninvaluableaidtothecircuit
designerortherepairman.Severalpossible
applicationsofthedual-traceoscilloscope will be
reviewedindetailtofamiliarizetheuserfurtherin
thebasicoperationofthisoscilloscope.
Frequency DividerWaveformsViewing:
Fig. 5 illustratesthewaveforminvolvedina basic
divide-by-twocircuit.Fig.A indicatesthe
referenceorclockpulsetrain.Fig.B andFig.C in-
dicatethepossibleoutputsofthedivide-by-twocir-
cuitry.Fig.6 alsoindicatesthesettingsofspecific
oscilloscope controlsforviewingthesewaveforms.
Inadditiontothesebasiccontrolsettings,the
TRIGGERING LEVEL control,aswellastheCH1
andCH2verticalpositioncontrolsshouldbesetas
requiredtoproducesuitabledisplays.Inthedraw-
ingofFig.5,thewaveformlevelsof2 divarein-
dicated.IfexactvoltagemeasurementsofCH1
andCH2aredesired,theCH1andCH2VARIABLE
controlsmustbeplacedintheCALposition.The
CH2 waveformmaybeeither that indicatedinFig.
5B orFig.5C.InFig.5C,thedivide-by-twoout-
putwaveformisshownforthe case wheretheout-
putcircuitryrespondstoa negative-going
waveform.Inthis case, the output waveformis
shifted with respecttotheleadingedgeofthe
Fig. 5 Waveformsindivide-by-twocircuit
referencefrequencypulsebya time intervalcor-
respondingto thepulsewidth.Whenobserving
twosignalshaving different cyclesimiltaneously,
thesignalhavinglowcycleshouldbetriggered.
Divide-by-8CircuitWaveforms:
Fig. 6 indicateswaveformrelationshipsfora basic
divide-by-eightcircuit.Thebasicoscilloscopeset-
tingsareidenticaltothoseusedinFig.5.The
referencefrequencyofFig.6Aissuppliedto the
Channel 1 inputandthedivide-by-eight output is
appliedtotheCH2input.Fig.6 indicatesthe time
relationshipbetweentheinputpulsesand output
pulses.
Inanapplicationwherethelogiccircuitryis
operatingatornearitsmaximumdesignfrequency,
theaccumulatedrise time effectsofthecon-
secutive stagesproducea built-in time propagation
delaywhichcanbesignificantina criticalcircuit
andmustbecompensatedfor.Fig.6Cindicates
thepossible time delaywhichmaybeintroduced
into a frequencydividercircuit.Byuseofthedual-
trace oscilloscope, theinputand output waveforms
can besuperimposed(ADDorSUB)to determine
theexactamountofpropagationdelay that occurs.
10
A. REFERENCE FREQUENCY PULSE TRAIN
(1000 PULSES PERSECOND)
LEADING EDGES MAYNOTBE
VISIBLE AT FAST SWEEP RATES
B.DIVIDE-BY-TWOOUTPUTSYNCHRONIZEDTO
LEADING EDGE OF REFERENCE PULSE
C DIVIDE-BY-TWOOUTPUTSYNCHRONIZEDTO
TRAILING EDGE OF REFERENCE PULSE

PropagationDelayTimeMeasurement:
Anexampleofpropagationdelayina divide-by-
eightcircuitwasgiveninthepreviousparagraph.
Significantpropagationdelaymayoccurinanycir-
cuit with severalconsecutivestages. This os-
cilloscopehasfeatureswhichsimplifymeasure-
mentofpropagationdelaytime.Fig.7 showsthe
resultantwaveformswhenthedual-tracepresenta-
tion iscombined into a single-tracepresentationby
selectingtheADD position oftheMODEswitch.
With CH2 PULL. INVERT switchinthenormalposi-
tion (pushedin)thetwoinputsarealgebraically
addedina single-tracedisplay.Similarly,inthein-
verted position (pulledout)thetwoinputsare
algebraicallysubtracted.Either position providesa
precise displayofthepropagation time (Tp).Using
proceduresgivenforcalibrated time measurement.
Fig. 7 UsingADDmodepropagation
time measurement
Tp canbemeasured.A moreprecisemeasurement
can beobtainediftheTp portion ofthewaveformis
expandedhorizontally. This maybedoneby pulling
theX10MAGcontrol.Italsomaybepossibleto
viewthedesired portion ofthewaveformata faster
sweep speed.
DigitalCircuitTimeDelayMeasurement:
A dual-traceoscilloscopeisa necessityindesign-
ing,manufacturingandservicing digital equip-
ment.A dual-traceoscilloscopepermits easy com-
parisonof time relationshipsbetweentwo
waveforms.In digital equipment,itiscommonfor
a largenumberofcircuitstobesynchronized,orto
have a specific time relationshiptoeachother.
Manyofthecircuitsarefrequencydividersas
priviouslydescribed,butwaveformsareoften
time-relatedinmanyothercombinations.Inthe
dynamicstate,someofthewaveformschange,
depending upon the input ormoremodeofopera-
tion.
Ffg. 8 showsa typical digital circuitandidentifies
several ofthepointsatwhichwaveformmeasure-
mentareappropriate.TheaccompanyingFig.8
shows thenormalwaveformstobeexpectedat
each ofthesepointsandtheir timing relationships.
The individualwaveformshave limited valueunless
their timing relationshiptooneormoreoftheother
waveformsisknowntobecorrect.Thedual-trace
oscilloscopeallowsthiscomparisontobemade.In
typicalfashion,waveformNo.3 wouldbedisplayed
onCH1andwaveformNo.4 through No.8 andNo.
10, wouldbedisplayedonCH2althoughothertim-
ingcomparisonsmaybedesired.WaveformsNo.
11 through No.13wouldprobablybedisplayedon
CH2.
Inthefamilyoftime-relatedwaveformsshownin
Fig. 9,waveformNo.8 orNo.10isexcellent sync
source forviewingallofthewaveforms;thereis
butone triggering pulseperframe.Forcon-
venience, external sync, anyofthewaveformsmay
bedisplayed without readjustmentofthe sync con-
trols.
With No.8 orNo.10usedasexternal triggering
source, anyofthewaveformsmaybedisplayed
without readjustmentofthe TRIG LEVEL control.
WaveformsNo.4 through No.7 shouldnotbeused
as the triggering sourcebecausetheydonotcon-
taina triggering pulseatthestartoftheframe.It
wouldnotbenecessarytoviewtheentire
waveformsasshowninFig.9 inall cases. Infact,
therearemanytimeswhena closerexaminationof
a portion ofthewaveformswouldbeappropriate.
EXPAND THISPORTION
FOR TIMEMORE PRECISE
MEASUREMENT
11
A REFERENCE FREQUENCY PULSE TRAIN
(1000 PULSES PERSECOND)
B IDEALDIVIDEBYEIGHTOUTPUT
C PROPAGATION DELAY INDIVIDEBYEIGHTCIRCUIT
Fig. 6 Waveformsindivide-by-eightcircuit
CH2 POLARITY
NORMAL
CH2 POLARITY
INVERT

Insuch cases, itisrecommended that thesyncre-
mainunchangedwhilethesweepspeedorX10
Fig. 8 Typical digital circuitusingseveraltime-relatedwaveforms
MAG usedbetoexpanedthewaveformdisplay.
12

ANY INDIVIDUAL ADDRESS ORFUNCTION
DATA BITMAYBE POSITIVE OR NEGATIVE
DEPENDING UPONTHE CODED INPUT
SUB = DISTORTION
ADJUST POSITION CONTROLS TO
SUPERIMPOSE WAVEFORMS DIRECTLY
OVER EACH'OTHER
Fig. 10Distortionmeasurement
T3
Fig. 9 Familyoftime-relatedwaveformsfromtypicaldigitalcircuitinFig.8
DistortionMeasurement:
An amplifierstageoranentireamplifier unit may
be measuredfor distortion with thisoscilloscope.
This typeofmeasurementisespeciallyvariable
when theslopeofa waveformmustbefaithfully
reproducedbyanamplifier.Fig.10showsthe
testingofa circuitusinga triangular wave, such as
is typicallyencounteredintherecoveredaudio out-
putof limiting circuitwhichprocedesthe
modulatoroftransmitter.Themeasurementmay
be madeusinganytypeof signal; merelyusethe
typeofsignalfortestingthatisnormallyappliedto
theamplifierduringnormaloperation.The
procedurefor distortion testingisasfollows.
ADJUST TOBOTH
WAVEFORMS ARE
SAME AMPLITUDE
AMP
No.1
AMP
No.2

1. Applythetypeofsignalnormallyencountered
intheamplifierundertest.
2. ConnectCH1probeto theinputofthe
amplifierandCH2probetotheoutputofthe
amplifier.Itispreferableifthetwosignalsare
notinvertedinrelationshipstoeachother,but
invertedsignalscanbe used.
3 SetCH1andCH2AC-GND-DCswitchesto
AC.
4.SettheMODEswitchtoALTorCHOP.
5.Set SOURCE switchtoCH1andadjust
controls asdescribedintheprocedurefor
synchronizing waveforms.
6.AdjustCH1andCH2POSITIONcontrolsto
superimpose thewaveformsdirectlyovereach
other.
7.AdjustCH1andCH2verticalsensitivity con-
trols(VOLTS/DIVand VARIABLE) so that the
waveformsareaslargeas possible withoutex-
ceeding thelimitsofthe scale, andso that
bothwaveformsareexactlythesameheight.
8.Now,setthe Mode switchtoADDandthe
CH2 polarityswitchtothe PULL INVERT posi-
tion.(Ifonewaveformisinvertedin
relationships totheother,usethenormalCH2
polarity.)
Adjust theverticalsensitivitycontrol(CH2
VARIABLE) fortheminimumremaining
waveform.Anywaveform that remainsequals
distortions; ifthetwowaveformsareexactly
thesameamplitudeandsamewaveformand
thereisnodistortion,thewaveformswill
cancel andtherewillbeonlya straight
horizontallinewillremainingonthe screen.
GatedRingingCircuit(burstcircuit)
The circuitandwaveformofFig.11areshownto
demonstratethetypeofcircuitinwhichthe
dual-traceoscilloscopeiseffectivebothindesign
andtroubleshootingapplications.
Fig. 11showsa burstcircuit.The basic settings
areidenticalto thoseofinFig.5.
WaveformEAisthereferencewaveformandis
appliedtoCH1input.Allotherwaveformsare
sampled atCH2andcomparedtothereference
waveformofCH 1. Thefrequencyburstsignalcan
beexaminedmorecloselyeitherbyincreasingthe
sweep time perdivisionto 0.5msperdivisionorby
pullingthePOSITIONcontrolto obtain10
timesmagnification.Thiscontrolcanthenbe
rotatedasdesiretocenterthedesiredwaveform
informationontheoscilloscope screen.
DelayLineTest:
The dual-tracefeatureofthe oscilloscope canalso
beusedto determinethedelaytimesoftransmis-
sion typedelaylinesaswellasultrasonictype
delay lines. Theinputpulsecanbeusedtotrigger
orsynchronizedtheCH1displayandthedelayline
outputcanbeobservedonCM2.Theinterval
betweenrepetitive pulses shouldbelargecom-
paredtothedelay time tobeobserved.Inaddition
todeterminingdelaytime,thepulsedistortionin-
herentinthedelaylinecanbedeterminedbyex-
aminationofthedelaypulseobservedonCH2
waveformdisplay.
Fig. 12showsthetypicaloscilloscopesettingsas
wellasthe basic testcircuit.Typicalinputandout-
putwaveformsareshownonthe oscilloscope dis-
play.Anypulsestretchingandripplecanbe
observed andevaluated.Theresultsofmodifying
theinputandoutputterminationscanbeobserved
directly.
A commonapplicationofthedelayline checks is
foundincolortelevisionreceiverstocheckthe"Y"
delaylineemployedinthevideoamplifiersection.
The inputwaveformandoutputwaveformarecom-
paredfordelaytime,usingthehorizontal sync
14
Fig. 11Gatedringingcircuitandwaveforms

pulseofthecompositevideosignalforreference.
The indicateddelayisapproximatelyonemicrose-
cond.Thedelayisapproximatelyonemicrose-
cond.In addition todeterminingthedelay
characteristics oftheline,the output waveform
reveals any distortion that maybeintroduced from
an impedancemismatchorgreatlyattenuated out-
putresulting from anopenline.
PULSE GENERATOR
5000PPS
sec.
PULSE WIDTH
INPUT
ULTRA SONIC DELAY
LINE (5Msec)
OUTPUT
Fig. 12Delaylinemeasurements
VIDEO
AMPLIFIER
USE 1/10 PROBE
FOR BOTHCHANNELS
DELAY LINE
*NOTE:SETTINGOF VERTICAL"
ATTENUATORS SHOULDBE
THE SAME.BUTMAYVARY
WIDELY, DEPENDINGONCIRCUIT
TYPE.
TO HORIZONTAL
AMPLIFIER
TO VIDEOOUTPUT
AMPLIFIER
NOTE: NO ELECTRICAL CONNECTION:
PLACE CLIP ONINSULATIONOF PLATE
CAP LEAD ORIN CLOSE PROXIMITYOF
HORIZONTALAMPLIFIER TUBE.
Fig. 13Checking"Y"delaylineincolortelevisionreceivers
ImprovingtheRatioofDesiredtoUndesired
Signals:
Insomeapplications,thedesiredsignalmaybe
riding ona largeundesiredsignalcomponentsuch
as 50Hz.Itispossibletominimizeorforpractical
purposeeliminatetheundesiredcomponent.Fig.
14showstheoscilloscopesettingsforsuchan
application.ThewaveformdisplayofCH1
indicatesthedesiredsignalandthe dotted line
indicatestheaverageamplitudevariation
ADJUST FORONE
COMPLETE CYCLE
AT 50Hz
SIGNAL
50Hz
START WITH CHOP
CHANGETOADD(CH2POLARITY
INVERT)
Fig. 14
Improvingdesired-to-undesiredsignalradio
15

correspondingtotheundesired50Hzcomponent.
The CH2displayindicatesa waveformofequal
amplitudeandidenticalphasetotheaverageofthe
CH1 waveform. With theMODEswitchsetto
ADD andtheCH1signalinverted,andbyadjusting
theCH2verticalattenuatorcontrol,and50Hz
componentoftheCH1signalcanbecancelledby
theCH2 input andthedesiredwaveformcanbe
observed.
Stereo AmplifierServicing:
Anotherconvenientusefora dual-traceoscil-
loscopeisin troubleshooting stereoamplifiers.If
identicalamplifiersareusedandthe output ofone
is weak, distorted orotherwiseabnormal,the
dual-traceoscilloscopecanbeefficientlyusedto
localize thedefectivestate. With anidentical sig-
nal appliedtotheinputsof both amplifiers,a
side-by-side comparisonof both unitscanbemade
byprogressivelysamplingidenticalsignalpointsin
both amplifiers.Whenthedefectiveormalfunctio-
ningstagehasbeenlocated,theeffectofwhatever
troubleshooting andrepairmethodsareemployed
can beobservedcanbeobservedandanalyzedim-
mediately.
Amplifier Phase ShiftMeasurements:
Phase measurementscanbemadebyseveral
method usingoscilloscopes.Typicalapplications
are incircuitsdesignedtoproducea specificphase
shift,andmeasurementofphaseshift distortion in
audioamplifiersandnetwork.Inallamplifiers,a
phase shiftisalwaysassociated with a changein
amplituderesponse.Forexample,atthe— 3 dB
response points,a phaseshiftof45°occurs.
Phase measurementscanbeperformedby
operatingtheoscilloscopeeitherinthedual-trace
modetomeasureamplifierphaseshiftdirectly.
Fig. 15illustratesthismethod.Inthis case, the
measurements arebeingmadeatapproximately
5000 Hz.The input signaltotheaudioamplifieris
used asa referenceandisappliedtotheCH1 input
jack.
The VARIABLE control isadjustedasrequiredto
providea completecycleofthe input waveform
displayedon8 divhorizontally.A waveformheight
of2 divis used. The8 divdisplayrepresents360°
atthedisplayedfrequencyandeachdivision
represents 45°ofthewaveform.
The signaldeveloped accross the output ofthe
audioamplifierisappliedtotheCH2 input jack.
The verticalattenuatorcontrolsofCH2are
adjustedasrequiredtoproducea peak-to-peak
waveformof2 divamplitudeasshowninFig.
15B. TheCH2 POSITION control isthenadjusted
so that theCH2waveformisdisplayedonthesame
horizontal axis astheCH1waveformasshownin
Fig. 15B.Thedistancebetweencorresponding
pointsonthehorizontal axis forthetwowaveforms
thenrepresentsthephaseshiftbetweenthetwo
waveforms. Inthis case, thezerocrossoverpoints
ofthetwowaveformsarecompared.Itisshown
that a differenceof1 div exists. This istheninter-
pretedasmeansa phaseshiftof45°.
Television Servicing:
Manyofthetelevisionservicingprocedurescanbe
performedusingsingle-traceoperation. These are
outlined laterintheapplicationssectioncovering
single-traceoperations.Oneoftheseprocedures,
viewingthe VITS (verticalintervaltestsignal),can
beaccomplishedmuchmoreeffectivelyusinga
dual-traceoscilloscope.As outlined inthe
single-traceapplicationssectionandasshownin
Fig. 16.the information ontheField1 andField2
verticalblankingintervalpulseisdifferent. This is
shownindetailinFig.16.Also,becausetheoscil-
loscopesweepissynchronizedtothevertical
blankingintervalwaveform,theField1 andField2
waveforms aresuperimposed onto eachother.
With dual-traceoperation,thesignal information
oneachblankingpulsecanbeviewedseparately
without overlapping.Fig.18indicatestheoscil-
16
ADJUST AS REQUIRED
FOR COMPLETE CYCLE
AF
SIGNAL
GENERATOR
AUDIO
AMPLIFIER
OUTPUT
LOAD
INPUT
Fig. 15Measureringamplifierphaseshift

loscopecontrolsettingforviewingthealternate
VITS.
Mostnetworktelevisionsignalscontaina built-in
testsignal(the VITS) thatcanbea veryvaluable
tool introubleshootingandservicingtelevision
sets. This VITS canlocalize trouble totheantenna,
tuner,IForvideosectionsandshownwhen rea-
lignmentmayberequired.The following procedu-
res showhowtoanalyzeandinterpretoscilloscope
displays ofthe VITS.
The VITS istransmittedduringtheverticalblanking
interval. Onthetelevisionset,itcanbeseenasa
bright whitelineabovethetopofthepicture,when
theverticallinearityorheightisadjustedtoview
theverticalblankinginterval(onTV sets with inter-
nal retraceblankingcircuits,theblankingcircuit
mustbedisabledtoseethe VITS).
The transmitted VITS isprecisionsequenceofa
specific frequences,amplitudesand waveshapes as
showninFig.16.
Television networksusetheprecisionsignalsfor
adjustmentandcheckingofnetworktransmission
equipment,butthetechniciancanusethemto eva-
luatetelevisionmultiburstsignalin VITS canalso
besetperformance.
The firstframeof VITS atthe"B"section(line18)
inFig.16begins with a whitereferencesignal,fol-
lowedbysinewavefrequenciesof0.5MHz,1.0
MHz,2 MHz,3 MHz,4 MHzand3.58MHz. This
sequence offrequenciesiscalledthe"multi-burst".
(MULTI-BURST)
3.58MHz
FIELD I
FIELD 2
(MULTI-BURST)
0.5I 2 3 3.58 4.2MHz
FIELD I 42
No.17
No.279
Fig. 16VITSsignal.Fields1 and2
17
VERTICAL BLANKINGINTERVAL(NO:1 ~ NO.21)
HORIZ. SYNC. PULSE
LINE No.17 No.18
No.279
No.280
VERTICAL BLANKINGINTERVAL(NO.263~ NO.282)
No.18
No.280

This multi-burst portion of the VITS isthe portion
thatcan be mostvaluable to thetechnician. The
second line of Field1 andthesecondline of Field 2
(lines 18 and280)maycontainthesine-squared
pulse, windowpulseandthe staircase of3.58MHz
burst at progressivelylightershading. These are
valuable to thenetwork,buthave less value to the
technician. As seen onthetelevision screen. Field
1 is interlacedwithField 2 sothatline 17is fol-
lowed by line279andline 18 isfollowed by line
280. Theentire VITS appearsatthe bottom ofthe
vertical blankingpulseandjustbeforethefirstline
ofvideo.
Now to analyze thewaveform. All frequencies of
themulti-burstaretransmitted at the same level,
butshould notbe equallycoupledthrough the
receiver due to itsresponsecurve.Fig.24shows
thedesiredresponse fora goodcolortelevision
receiver, identifying each frequency ofthe
multi-burstandshowingtheallowableamount of
attenuation for each. Rememberthat — 6 dB
equals half the referencevoltage (the2.0MHz
modulationshould be used for reference).
To localizetrouble,start by observingthe VITS at
thevideodetector. This willlocalizetrouble toa
point eitherbefore or after the detector. Ifthe
multi-burst is normal atthe detector,check the
VITS on other channels. If somechannelslook
okay butothersdonot,youprobablyhavetuner or
antenna-system troubles.Don'toverlook the
chance of theantennasystemcausing"holes" or
tilted response on some channels. If the VITS is
abnormalatthevideodetectoronall channels, the
trouble is probably inthe IFamplifier stages.
As anotherexample,letus assume thatwehave a
set onthe benchwith a verypoorpicture. Our
oscilloscope shownthe VITS at thevideodetector
to be aboutnormalexceptthat the burst at2.0
MHz islowcompared to theburstsoneither side.
This suggests anIF trap is detuned into the
passband, chopping out frequenciesabout 2 MHz
below the picturecarrierfrequency.Switch to
anotherchannelcarrying VITS. If the same thing is
seen, then our reasoning is right, andtheIF
amplifierrequiresrealignment.
Ifthepoorresponse at2 MHzisnot seen onother
channels, maybeanFMtrap at thetunerinput is
misadjusted, causing a bite on onlyonechannel.
Other trapsattheinputofthesetcouldsimilarlybe
misadjusted or faulty.
If the VITS response atthe detector output is
normal for all channels, thetroublewill beinthe
videoamplifier.
Look for openpeakingcoils,off-valueresistors,
solder bridges across foil patterns,etc.
Withdual-traceoscilloscopeoperation, the signal
information on each verticalblankingintervalcan
be viewedseparately without traceoverlapping,
although the informationalternateswith each
field. Fig. 18 indicates the oscilloscopecontrol
setting for viewing the alternateverticalblanking
intervals.
1. Set a colorTVreceiver tothe stationtrans-
mitting colorsignalscontaining VITS.
2. Themethodshown in Fig.18isused to obtain
Field 2 verticalsign on CH1.
3. Setthe oscilloscope andthe receiver for
operation.ConnecttheCH1probe to thetest
point of videodetector or otherdesiredtest
point inthe videosection ofthe television
receiver.
4. Setthe SYNC switcheasfollows:
A. Ifthe sync and blankingpulses ofthe
observed videosignalarepositive,usethe
VIDEO + position.
B. Ifthe sync and blankingpulses are
negative, usethe VIDEO— position.
5. Adjustthesweeptime VARIABLE control so
that 2 verticalfieldsaredisplayed on theos-
cilloscope screen.
6. ConnecttheCH2probe to the same test point
as doesthe CH 1 probe.
7. SettheMODEswitch to ALTposition.
8. Place the sweeptime VARIABLE in theCAL
position.
9. Setthe SWEEP TIME/DIV control to the 0.1
ms position to expand the display by
increasing the sweep speed. The VITS
18
RESPONSE-DB
FREQUENCY—MHz
Fig. 17
Color TVIF amplifier response curve

VIDEO
VERTICAL
SYNC .
PULSE
IF
AMP
TELEVISIONSET SOUND
IF
COLOR
IF
START WITH
2MS/div
PICTURE
TUBE
Fig. 18Set-upforviewingfields1 and2 ofVITSinformation
informationwillappeartowardthe right hand
portion oftheexpanedwaveformdisplays.
The waveforminformationoneachtracemay
appear asshowninFig.16. Because thereis
noprovisionforsynchronizingtheoscilloscope
displaytoeitherofthetwofieldswhich
comprisea completeverticalframe,itcannot
bepredictedwhichfielddisplaywillappearon
CH1 orCH2.
10. Pullthe<> POSITION controloutwardto
obtainanadditionalX10magnification.
Rotate thecontrolina counterclockwisedi-
rectionmovingthetracetothe left until the
expanded VITS informationappearsasshown
inFig.16. Because ofthelow repetition rate
andthehighsweepspeedcombination,the
brightnesslevelofthesignaldisplayswillbe
reduced.
11. OncetheCH1andCH2displayshavebeen
identifiedasbeingeitherField1 orField2
VITS information,theprobecorrespondingto
thewaveformdisplaywhichistobeusedfor
signal-tracingandtroubleshootingcanbe
used, andtheremainingprobeshouldbe left at
thevideodetectortest point toinsurethatthe
sync signalisnotinterrupted.Ifthe sync sig-
nal isinterrupted,thewaveformdisplaysmay
bereversed because, aspreviouslyexplained,
thereisnoprovisionintheoscilloscopeto
identifyeitherofthetwoverticalfieldswhich
comprisea completeframe.
19
VERTICAL
BLANklNG
VIDEO
DETECTOR
VIDEO
AMP VIDEO
AMP

SINGLE-CHANNEL APPLICATIONS
introduction.
In addition tothedual-traceapplicationspreviously
outlined,thereare,ofcourse,manyservicingand
laboratoryapplicationswhereonlysingle-traceor
single-channel operationoftheoscilloscopeisre-
quired.BysettingtheMODEswitchtoCH2and
usingtheCH2amplifier,manyflexibleoperations
willbeachieved;and,inaddition,byplacingthe
MODE switchtoADDandtheCH2polarityswitch
tothe PULL INVERT position.Whateverwaveform
is obtainedcanbeinvertedinpolarityifdesiredby
theoperator.
Television Servicing:
A triggeredsweeposcilloscopeisadvantageousin
servicing andaligningtelevisionreceivers. This
oscilloscopealsoincludesseveralfeaturesthat
were incorporatedtomaketelevisionservicingand
VIDEO signalobservationeasierandmore
comprehensive.
These featureincude:
*Withthe SYNC switchsetto VIDEO position,
the SWEEP TIME/DIV controlautomatically
selects the VIDEO-FRAME sync atsweep
speeds appropriateforviewingframeand
VIDEO-LINE sync atsweepspeedsappropriate
forviewinglines.
*Widebandwidthforhighresolutionvideoand
highspeedpulsepresentation.
Single-trace OperationandPeak-to-Peak
VoltageReadings:
For generaltroubleshootingandisolationof
troublesinalmostanyelectronicequipment,the
oscilloscopeisanindispensableinstrument.It
providesa visualdisplayoftheabsenceorpresence
ofnormalsignals. This method(signal-tracing)
may beusedtotracea signalbymeasuringseveral
pointsinthesignalpath.Asmeasurements
proceedalongthesignalpath,a point maybe
found wherethesignaldisappears.Whenthis
happens, thesourceof trouble hasbeenlocated.
However,theoscilloscopeshownmuchmorethan
themerepresenceorabsenceofsignals.It
providesa peak-to-peakvoltagemeasurement.
The schematicdiagramoraccompanyingservice
dataontheequipmentbeingservicedusually
includes waveformpictures.Therewaveform
pictureincludetherequiredsweeptimeandthe
normalpeak-to-peakvoltage.Comparethe
peak-to-peakvoltagereadingsontheoscilloscope
with thoseshownonthewaveformpictures.Any
abnormalreadingsshouldbefollowedbyadditional
readingsinthesuspectedcircuits until the trouble
is isolatedtoassmallan area aspossible.
CompositeVideoWaveformAnalysis
Probablythemost important waveformin
televisionservicingisthecompositewaveform
consistingofthevideosignal,theblankingpedestal
signal andthe sync pulses.Fig.19andFig.20
show typicaloscilloscopetraceswhenobserving
compositevideosignalssynchronized with ho-
rizontal sync pulsesandverticalblankingpulses.
Compositevideosignalscanbeobservedatvarious
stages ofthetelevisionreceivertodetermine
whethercircuitsareperformingnormally.
Knowledgeofwaveformmakeup,theappearance
ofa normalwaveform,andthe cause ofvariousab-
normalwaveformshelpthetechnicianlocateand
correctmanyproblems.Thetechnicianshould
studysuchwaveformsina televisionreceiver
knowntobein good operatingcondition, noting
thewaveformatvariouspointsinthevideo
amplifier.Tosetuptheoscilloscopeforviewing
compositevideowaveforms,usethe following
procedures:
1. Turnthetelevisionsettoa localchannel.A
testtapeora signalgeneratoralsocanbeused
forservicework.
2. SettheMODEswitchtoCH2position.
3. Setthe SWEEP TIME/DIV switchtothe10 us
positionforobservingTVhorizontallinesorto
the2 mspositionforobservingTVvertical
frames.
4. Setthe SYNC switchto VIDEO + orVIDEO-
position.
5. Setthe SOURCE switchtoINTposition.
6. Best overall sync performanceisobtained
whenthe TRIG LEVEL/PULL AUTOcontrolis
pushedin.Itmaybepulledoutinitiallyto
providecontinuoussweepduringset-up.
7. SettheCH2 AC-GND-DC switchtotheAC
position.
8. Connectthegroundclipoftheprobetothe
chassis. Withtheprobesetfor10: 1
attenuation,connectthetipoftheprobetothe
videodetector output.
9. SettheCH2 VOLTS/DIV switchforthelargest
verticaldeflectionpossible without going
offscale.
10. If necessary, rotatethe TRIG LEVEL controlto
a positionthatprovidesa synchronizeddisplay.
11. Adjustthesweeptime VARIABLE fortwoho-
rizontallinesortwoverticalframesof
20