ScienTECH 820 User manual

30 MHzOscilloscopewithColorLCD Digital
Readout, ComponentTester, DigitalMultimeter and Power Supply
TechlabScientech820
ProductTutorial
Ver. 1.2
Designed&ManufacturedinIndiaby:
AnISO9001:2008 company
ScientechTechnologiesPvt. Ltd.
94, ElectronicComplex, Pardesipura, Indore-452 010 India,
[phone], : [e-mail] , : www.ScientechWolrd.com

TechlabScientech820
2
30 MHzOscilloscopewithColorLCD Digital
Readout, ComponentTester, DigitalMultimeter and Power Supply
TechlabScientech820
TableofContents
1. SafetyInstructions 3
2. Introduction4
3. Features5
4. TechnicalSpecifications6
5. FrontPanelDiagram12
6. FrontPanelControl12
7. BackDiagram&Control16
8. OperatingInstructions17
9. ComponentTester23
10. Warranty24
11. ListofContents24

TechlabScientech820
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SafetyInstructions
Readthefollowing safetyinstructionscarefullybeforeoperatingtheproduct.
Toavoidanypersonalinjury, ordamagetotheproduct, oranyproductsconnectedto
it;
Donotoperatetheinstrumentifyoususpectanydamagewithin.
Theinstrumentshouldbeservicedbyqualifiedpersonnelonly.
ForyourSafety:
UseproperMainscord: Useonlythemainscorddesignedforthisproduct.
Ensurethatthemainscordissuitableforyour
country.
Ground theInstrument:Thisproductisgroundedthroughtheprotectiveearth
conductorofthemainscord.Toavoidelectricshock
thegroundingconductormustbeconnectedtothe
earthground.Beforemaking connectionstotheinput
terminals,ensurethattheinstrumentisproperly
grounded.
ObserveTerminalRatings: Toavoidfireorshockhazards, observeall ratingsand
marksontheinstrument.
UseonlytheproperFuse: Usethefusetypeandratingspecifiedforthisproduct.
UseinproperAtmosphere: Pleaserefertooperatingconditionsgiveninthe
manual.
1. Donotoperateinwet/dampconditions.
2. Donotoperateinanexplosiveatmosphere.
3. Keeptheproductdustfree, cleanand dry.

TechlabScientech820
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Introduction
TechlabScientech820 isanidealInstrumentforElectronics,Electrical&
InstrumentationLaboratories.ThisTechlab820 hasOscilloscope,DigitalMultimeter
andDCPowerSupplyinacompactspacesavinghousing.TheScientech820forms
anIndependentTestLabformanyapplications.

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Features
•2Channel-4Trace Display
•40 MHzTriggerBandwidth
•ScientechDigitalMultimeter
•DCPowerSupply±12 V&5V
•Component&ContinuityTester
•Microcontrollerbaseddesign
•AlphanumericLCDwithbacklit
•AlternateTriggering
•VariableHoldOff&LineTriggering
•DigitalReadoutwithbacklitColorLCD
DigitalMultimeter
•Powersupply:230V/110VAC
•Manualrange
•4½-digitlargeLCDdisplaywithbacklight(displaying range:75×40mm),
maxreading:19999
•Voltagemeasurementup to1000VDCand750VAC.
•DC, ACcurrentup to20A
•ACVfrequencyresponse:50KHz
•Frequency,resistance,capacitance measurement,triode,diodecheckand
continuitytest
•Overloadprotection;250Vrms.

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TechnicalSpecifications
Oscilloscope
OperatingModes:
ChannelI, ChannelII, ChannelI&II
alternateorchopped(approximately
350 KHz), X-Yoperation(Ratio1:1
InputviaCHII),Add/SubCHI±CH
II,InvertCHII.
Verticaldeflection(Y):
Identicalchannels
Bandwidth: DC-30 MHz(-3dB)
RiseTime: 12ns(approximately).
Deflectioncoefficients:
Micro-controllerbased12 calibratedsteps
5mV/cm–20 V/cm(1-2-5sequence).
ElectronicControlDisplayonColorLCD
Accuracy: ±3%
InputImpedance:
1M || 30 pF(approximately)
Input: BNCConnector
Inputcoupling: DC-AC-GND
MaximumInputvoltage: 400 V(DC
+PeakAC).
TimeBase:
Timecoefficients: Micro-controller
based18 calibratedsteps,0.5 µs/cm-
0.2s/cm(1-2-5sequence).Electronic
controldisplayonColorLCD.
Accuracy: ±3%(incalposition)
Magnifier: X10
Sawtooth: 5Vpp approximately
HighestTBspeed:20 ns
Hold-Off: VariableControlforStable
Triggering.
TriggerSystem:
TriggerBandwidth: 40MHz
Modes: Auto/Level
Source: CHI, CHII,Alt-CHI&CHII,
Ext.
Slope: PositiveorNegative
Coupling: AC
Sensitivity: Internal0.5div, External0.8V
(approximately).
HorizontalDeflection(X): InputviaCHII
Bandwidth: DC-3MHz(-3dB).
X-Ymode: PhaseShift<3°at60KHz.
Deflectioncoefficients: Micro-controller
based12 calibratedsteps5mV/mc-20
V/cm(1-2-5sequence). ElectronicControl
DisplayonColorLCD
InputImpedance: 1M || 30 pF
(approximately)
Input: BNCconnector
Inputcoupling: DC-AC-GND
MaximumInputvoltage: 400V(DC+
PeakAC)
ComponentTester (BuiltinSingleTouch)
TestVoltage: Maximum8.6Vrms (Open
circuited)
TestCurrent: Maximum8mArms (Short
circuited)
TestFrequency: 50 Hz,Testcircuit
groundedtochassis.
ContinuityTester:
Beepersounds<75 (approximately).
DC PowerSupply:
FixedOutputVoltage:5V/500mA
± 12 V/250mA

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GeneralInformation:
CathodeRay Tube:
140 mm Rectangulartubewithinternal
graticule. P31 Phosphor
Acceleratingpotential: 2KV
(approximately)
Display: 8x10 cm
Trace Rotation: Adjustableonfrontpanel
Calibrator: SquareWaveGenerator1
KHz(approximately), 0.2Vpp ±1%for
probecompensation.
ZModulation: TTL level
Stabilized PowerSupply: Alloperating
voltagesincluding theEHT
MainsVoltage: 230V±10%;50/60 Hz.
PowerConsumption: 65 VA
(approximately)
ColorDisplay: LCDType:65KColor
TFT, NegativeTransmissive
Resolution:128(W)×128(H)
Viewing direction:6O'clock
ScreenSize:1.51”
Weight(approx): 9Kg. (approximately)
Dimensions(mm): W325 xD370 xH215
OperatingTemperature: 0-40°C;80%RH

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Scientech61 DigitalMultimeterTechnicalSpecifications
Accuracy=±(reading % thelowesteffectivedigit)preheatingtime:30min.
Temperatureforaccuracyguarantee:(32 ±5)°C,R.H<75%,oneyearguaranteedfrom
theproductiondate
DC Voltage(DCV)
Range AccuracyResolution
200Mv
±(0.5%RDG+3) 10uV
2V 100uV
20V 1mv
200V 10mV
1000V ±(0.1%RGD+5) 100mV
Inputresidence:10MΩforall ranges
Overloadprotection:200mVrange:250VDCorACpeakvalue.otherrange:
1000VDCorACpeakvalue
AC Voltage(DCA)
Range Inputfrequency Accuracy Resolution
200mV 50Hz-50 KHz
±(0.8%RGD+80)
10Uv
2V
50Hz-20KHz 100uV
20V
200V 50Hz-5KHz 10mV
750V 50Hz-400Hz ±(1.0%RGD+50) 100mV

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Theinputvalueforaccuracyguarantee shouldbelargerthan10%ofrange.Input
resistance:2M Ωforall range.
Overloadprotection:200mVrange:250VDCorACpeakvalue,otherrange:1000V
DCorACpeakvalue.
DC Current(DC):
Range Accuracy Resolution
20mV ±(0.35%RGD+10) 1uA
200mV 10uA
2A ±(0.8%RGD+10) 100uA
20A 1mA
MaxInputvoltagedrop:200mV
Max.Inputcurrent:20A(within15s)
Overloadprotection:2A/250Vfused, 20A/250Vfused
AC Current(ACA)
Range Inputfrequency Accuracy Resolution
200mA 50Hz-5KHz ±(0.8%RDG+80) 10uA
2A
50Hz-400Hz ±(1.0%RDG+50) 100UA
20A 1mA
Maxinputvoltagedrop:200mV
MaxInputcurrent:20A(within15s)
Overloadprotection:2A/250Vfused, 20A/250 Vfused

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Resistance ( )
Range Accuracy Resolution
200 Ω±(0.1%RGD+20) 0.01 Ω
2K Ω
±(0.1%RGD+5)
0.1Ω
20K Ω1 Ω
200K Ω10 Ω
2m Ω100 Ω
20M Ω± (0.4%RGD+5) 1K Ω
Openvoltage:lessthan3V
Overloadprotection:250 VDCorACpeakvalue
Capacitance (CAP)
Range Accuracy Resolution
20nF
±(3.5%+20) 1nF
2uF 100nF
200KHz ±(5%+30) 10nF
Measuring frequency:approximately400Hz
Overloadprotection:36 VDCorACpeakvalue
Frequency(Freq)
Range Accuracy Resolution
20KHz
±(1.0%RGD+20) 1Hz
200KHz 10Hz
Inputsensitivity:500mVrms
Overloadprotection:250VDCorACpeakvalue(within15s)

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HFEMeasuring
Range Displaying Testcondition
HFE NPNORPNP 0-1000.0 Basiccurrentisapprox.10µA,vce is
approx.3V
Diodeand ContinuityTest
RangeDescription Testcondition
Themeasuring valueistheapproxvaluefor
forwardvoltagedrop.whentheresistanceunder
testedislessthan70 Ω±20 Ω,buzzersoundand
displaytheapproxvaluetheopenvoltageis
approx.3V
ForwardDCAis
approx.1mA
,backwardDCV
islessthan3V
Overloadprotection:250 VDCandACpeakvalue.
(Subjecttochange)

TechlabScientech820
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FrontPanelDiagram

TechlabScientech820
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FrontPanelControls
(1) Power‘On/Off’ :Pushbuttonswitchforsupplying powerto
instrument.
(2) X10 :Switchwhenpushedgives10 timesmagnification
oftheXsignal.
(3) XY :Switchwhenpressedcutsoffthetimebase&
allowsaccess totheexternalhorizontalsignalto
befedthroughCH2(usedforX-Ydisplay).
(4) CH1/2&Trig1/2 :Switchselectschannel&triggersource (released
CH1,Trig1&pressedCH2, Trig2).
(5) Mono/Dual:SwitchselectsMonoorDualtrace operation.
(6) Alt/Chop/Add :SwitchselectsalternateorchoppedinDualmode.
IfMonoisselectedthenthisswitchenables
additionorsubtractionofchanneli.e.CH1±CH
2.
(7) Ext :Switchwhenpressedallowsexternaltriggering
signaltobefedfromthesocketmarkedTrigger
Input(27).
(8) Line :Switchwhenpresseddisplayedsignal
synchronizedwithmainslinefrequency.
(9) Alt :SelectsalternatetriggermodefromCH1&CH2.
Inthismodeboththesignalsaretriggered
simultaneously.
(10) Slope(+/-) :Switchselectstheslopeoftriggering,whether
positivegoingornegativegoing.
(11) Auto/Level :SwitchselectsAuto/Levelposition.Autoisused
togettrace whennosignalisfedattheinput.In
Levelpositionthetriggerlevelcanbevariedfrom
thepositivepeaktonegativepeakwithLevel
Control.
(12) Level :Controlsthetriggerlevelfrompeaktopeak
amplitudeofsignal.
(13) TBVar :Controlsthetimespeedinbetweentwostepsof
Time/Divswitch.Forcalibrationputthispotfully
anticlockwiseatCalposition.
(14) DigitalReadout :LCDwindowfordisplaying DigitalReadoutfor
Volt/Div. &Time/Div. settings.
(15) YShift1&2 :Controlsprovidedforverticaldeflectionoftrace
foreachchannel.
(16) InvertCH2 :SwitchwhenpressedinvertpolarityofCH2.

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(17) Trace Sep :Trace Separatorx1&x10 in4trace operation
(Alt).
(18) Intensity :Controlsthebrightnessofthetrace.
(19) TR :Trace Rotationcontrolsthealignmentofthetrace
withgraticule(screwdriveradjustment).
(20) Focus :Controlsthesharpnessofthetrace.
(21) PowerLED:ItisindicationforPowerSupplyOn/Off
(22) Power :Pushbuttonswitchtosupplypowertopower
supplyunit.
(23) +5VSocket:Outputsocketfor+5VDC.
(24) G:Commongroundsocketforpowersupplies.
(25) +12VSocket :Outputsocketfor+12VDC.
(26) -12VSocket:Outputsocketfor-12VDC.
(27) CalOut :Socketprovidedforsquarewaveoutput200 mV
usedforprobecompensationandchecking
verticalsensitivity, etc.
(28) ExternalTriggerInput :Socketprovidedtofeedexternaltriggersignalin
ExternalTriggermode.
(29) Volts/DivCH1:SwitchselectsVolt/Div. stepforCH1&CH2
(30) CH1(Y)& CH2(X) :BNCconnectorsserveasinputconnectionforCH
1&CH2.Channel2inputconnectoralsoserves
asHorizontalexternalInput.
(31) DC/AC/GND :Inputcouplingswitchforeachchannel.InACthe
signaliscoupledthrough0.1MFDcapacitor.
(32) Time/Div :SwitchselectsTime/Div. steps.
(33) ComponentTesterInput: TotestanycomponentsintheCTmode,putone
testprodinthissocketandconnecttheothertest
prodingroundsocket.
(34) XShift :Controlshorizontalpositionofthetrace.
(34.) Normal/Alternate :SwitchselectsNormal(x1)orAlternately
expanded(x1&x10)simultaneouspositions.
(35.) Hold‘Off’ :ControlsHoldOff timebetweensweeps.Usedfor
StableTriggeringofcompositesignals.
(36.) ComponentTester :SwitchwhenpressedstartsComponenttester
operation.
(37.) XShift :Controlshorizontalpositionofthetrace.
(38.) LCD Display: LCDDisplayedparametersforDigitalMultimeter

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(39.) HoldKey
(40.) Capacitance measuringplug
(41) 20AInputterminal
(42) Less than2Ainputterminal
(43) FunctionKnob:
(44) HFEPlug
(45) COM
(46) V Hzinputterminal

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BackPanelControls
(47) Powerswitch
(48) 220/110Vswitch
(49) Fuse
(50) Powerplug
(51) Fuse :350 mAfuseisprovidedatthebackpanel.Spare
fuseisprovidedinsidetheinstrument.
(52) Zmod:Bananasocketprovidedformodulatingsignal
inputi.e. Z-modulation.
(53) :Bananasocketprovidedforsawtoothoutput
(5Vpp approximately).

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OperatingInstructions
GeneralInformation:
The30 MHzDualTrace TechlabScientech820 isacompact,lowlineandjusttrouble
freenewgenerationMinilab. Itistechnicallyadvanced, asparticularlyillustratedbythe
increaseduseofmicrocontrollercircuits.Thelogicalarrangementofthecontrols&
connectorsmakesiteasytobecomefamiliarwiththeoperationoftheinstruments.
However,even,experiencedusersofOscilloscopesshouldreadthefollowing
instructionsthoroughlybeforeusingtheinstrument.
OperatingConditions:
Ambienttemperaturerangeforoperation:0°C-40°C;80%RH
Ambienttemperaturerangeforstoragetransportation:-20°Cto+70°C.
Theinstrumentshouldbeplacedinacleananddryroomandshouldbeoperatedin
normalposition;however, theconvectioncooling mustnotbeimpaired.
FirstTimeOperation&Presetting:
Atthetimeofdelivery,theinstrumentissetat230 VACmainsvoltage.Toobtaina
display:
•Allpushbuttonsshouldbeinthereleasedposition.
•Instrumentisturned‘On’bypressing "Power"pushbutton.AnLCDindicates
thattheinstrumentis‘On’.Itisrecommendedtoswitchontheinstrumentfor
about30minutespriortocommencementofanycalibrationcheck.
•Ifnotrace isvisibleafterawarm-up ofoneminute:
a. Check"Intensity".Itispossiblethatthiscontrolneedstobeincreased,
rotateknobclockwise.
b. BringX&Y“Shift”controlsinthecentre.CheckAuto/Levelcontrolsbring
itinAutoposition.
•Ifonlyadotappears[Caution,theCRTphosphorcouldbedamagedunderthis
conditionprobably]thepushbuttonforXY ispressed.Ifthisisso,itshouldbe
released.
•Now,thetrace shouldappearandthe"Intensity"controlshouldbeadjustedfor
averagebrightness, whileoptimumsharpnessisobtainedbyadjustingthe"Focus"
control.
•Atthesametimebothinputcouplingswitch"DC-AC-Gnd"shouldbeinthe
"Gnd"position.Thus,theinputsoftheY-amplifiersaregroundedpreventingthe
introductionofunwantedsignals.
•CheckTime/Div. &Volts/Div.functionbyusing rotaryknobs.

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TypeofSignalVoltage:
Allsignalswhosefrequencyspectrumisbelow30 MHzcanbedisplayedonthe
Scientech820
•SimpleelectricalprocessessuchassinusoidalRFandAFsignalsor50 Hzripple
voltagesareeasilydisplayedbytheinstrument.
•Howevertodisplaysquareorpulseshapedsignalsonehastorememberthattheir
harmoniccontentmustalsobetransmittedalongwiththefundamental.Hence the
bandwidthoftheverticalamplifiermustbesetconsiderablyhigherthanthe
repetitionoflogicandpulsesignals,particularly,ifthedutycyclepermanently
changesduringtheoperation.Otherwise,thedisplaywillmoveup anddown
withoutanychange.
•Displayofcompositesignalswhichdonotcontainanysuitablelevelcomponents
fortriggeringcausegreaterproblems.Toobtainawell triggereddisplayinsuch
cases,itisnecessarytousethetimebase'Var'control.
•TobeusedasanACorDCvoltageamplifier,eachchannelisprovidedwithan
'AC-DC'switch.UndernormalconditionsACmodeisused.UseofDCmodeis
recommendedonlywhenacquisitionoftheDCvoltagecontentsignalis
absolutelynecessary.However,wheninvestigatingverylowfrequencypulses,
disturbing rampoffsetmayoccurwithACcoupling.InthiscaseDCcoupling
mustbeusedDCvoltagesarealwaysmeasuredinthe'DC'position. DCoperation
istoberecommendedevenfortherepresentationoflogicandpulse,particularly
underconditionswhenthedutycyclechangespermanentlyduring theoperation,
else, thedisplaywillmoveup anddownwithchange.
MagnitudeofSignalVoltage:
Generallyalternatingvoltagedatanormallyreferstoeffectivevalues(rms=rootmean
squarevalue). But, forsignalmagnitudeandvoltageinOscilloscopetests thevoltpeak-
to-peak(Vpp)value(whichisthevalueofrealpotentialdifference betweenthemost
positiveandmostnegativepointsofasignalwaveform)istaken.
ToconvertavalueofsinusoidalwavedisplayedontheTechlabscreentoitseffective
value,theresulting voltagepeak-to-peakvaluehastobedividedby2.83.Conversely
Vpp is2.83 timesVeff(Vrms)andisequivalenttothesinusoidalvoltage. Therelations
ofthedifferentvoltagesmagnitudeisgiveninthefigure1.

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TheminimumrequiredvoltageontheYinputforadisplayof1cmamplitudeis2
mVpp.However,smallersignalscanbedisplayed.Thedeflectioncoefficientsonthe
inputattenuatorsareindicatedbyVpp/cmormVpp/cm.Themagnitudeoftheapplied
voltageisascertainedbymultiplying theselecteddeflectioncoefficientwiththedisplay
amplitudeincm.IfanattenuatorprobeX10 isused,afurthermultiplicationby10is
requiredwithdirectconnectiontotheYinput,signalsupto160 Vpp canbedisplayed.
Iftheappliedsignalissuperimposedonadirectvoltage, thetotalvalue(DCPeakvalue
ofthealternatingvoltage)ofthesignalontheYinputmustnotexceed400 V.
TimeValuesofSignalVoltage:
Asaruleall signalsdisplayedarerepeatingprocess having arecurringfrequencyor
repetitionratewhichcanbedesignatedas"periodspersecond".Forthis,theunitsare
indicatedonthe"Timebase"switch µs/cm,ms/cmands/cm.accordingly,the
"Timebase"dialissubdividedintotwosectors.Thedurationofasignalperiodora
portionofthewaveformisobtainedbymultiplying therelevanttimefinecontrol
marked"Var"mustbeinitscalibratedpositionforaccuratemeasurement(arrow
horizontalandpointingtotheleft).
Ifthetimeis relativelyshortascomparedwiththecompletesignalperiod, anexpanded
timescale(X10)shouldbeapplied. Theascertainedtimevalueistobedividedby10 in
thiscase. Wheninvestigatingthepulsebehaviourofasignalvoltage, thecriticalfeature
istherisetimeofthevoltagestep.Toensurethattransients,rampoffsets,and
bandwidthlimitsdonotundulyinfluence themeasuringaccuracy,therisetimeis
generallymeasuredbetween10%and90%oftheverticalpulseheight.

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ConnectionofTestSignal:
ThesignaldisplayedshouldbefedtotheYinputoftheTechlabthroughashieldedtest
cableorbyanX10attenuatorprobe.Theuseofthesecableswithhighimpedance
circuitsisonlyrecommendedforrelativelylowfrequencies(uptoapproximately50
KHz).Forhigherfrequencies,andwhenthesignalsource isoflowimpedance,acable
ofmatchedcharacteristicimpedance (usually50 Ω)isrecommendedwhen
investigatingsquareorpulsewaveformswithfastrisetimes,transientphenomenonon
boththeedgeandtopofthesignalmaybecomevisible,ifthecorrectterminationisnot
used.Itmustberememberedthatthe50 Ωthroughterminationwill dissipatea
maximumof2watts. IfanX10 attenuatorprobeis used, noterminationisnecessary. In
thiscase,theconnectingcableismatcheddirectlytothehigh-internalimpedance
sourcesareonlyslightlyloaded.Therefore,itisadvisabletouseX10 probeswhenthe
voltageloss duetotheattenuationoftheprobeiscompensatedbyahighersensitivity
settingonthe TechlabScientech820.Usingofprobesalsoprovidesseriesprotection
fortheinputoftheTechlabamplifier.
Note: Thatall attenuatorprobesmustbecompensatedinconjunctionwiththe
Techlab.
Itisimportanttorememberthatfordisplayofsmall signalvoltagethepositionofthe
groundpointonthetestcircuitshouldalwaysbelocatedascloseaspossibletothe
measuringpointotherwiseitwillresultinserioussignaldeformationfromany
invalidatedcurrentsthroughgroundleadsorchassisparts.Alsogroundleadsofthe
attenuatorprobesshouldbeideallybeing asshortandthickaspossible.
Ifafterconnectingthetestsignal,thetrace disappearssuddenly,thesignalamplitude
maywellbetoogreat,i.e.theamplifierisoverscaled.Insuchcase,theattenuator
switchshouldbeturnedanticlockwise,until theverticaldeflectionisonly3-7cm.For
signalamplitudesgreaterthan160 Vpp anX10 probeshouldalwaysbeused.Ifafter
connectingthesignaltheintensityofthetrace islow, itispossiblethattheperiodofthe
testsignalissubstantiallyslowerthatthevaluesetofthe"Timebase"switch.This
controlshouldthenbeturnedanticlockwisetoacorrespondingslowertimecoefficient.
ProbeCompensation:
Fortheundistorteddisplayofsignals, theX10 attenuatorprobemustbecompensatedto
matchtheinputimpedance oftheverticalamplifier.Thisisdonebyconnectingprobe
tiptothemini-socketontheinstrumentmarkedwithasquarewave,andadjustingthe
trimmertoolsuppliedwiththeprobe.In Scientech820 theprobecompensationis
easilyachievedduetothebuiltinSquareWaveGeneratorwitharepetitionfrequency
ofapproximately1KHzandanoutputvoltageof0.2Vpp.Thecorrectdisplayisshown
infiguregivenbelow.
The"Timebase"switchshouldbeinthe0.2ms/cmposition.Thesignalhasan
amplitudeof0.2Vpp ±1%. Iftheattenuatorswitchissetto50 mV/cm, thedisplaywill
haveaheightof4cms(1:1probe).Since anattenuatorprobeisconstantlysubjectedto
considerablestresses, thecompensationshouldbefrequentlychecked.
F