Tektronix 494AP AdJustmantProcedure- 494A/4g4ApServiceVot. .l, TIME/DIVAUTO Triggeringfreerun

AdJustmantProcedure- 494A/4g4ApServiceVot. .l

Figure5-3. Adiustmentandtestpointlocationson Hlgh Voltagemodule.

(3)Switch POWERback on. After the instrument initializes, activate 2 dB/Dtv and switch Digital Storageoff.

(4)Adjust IntensityLimit R1027(Figure5-2)for a voltagereadingof 0.9 V at Tp402B.

(5)Switch POWERoff and re-instailthe jumper P4036on the HighVottageboard. Turn pOWERon

and adjustthe INTENSITyfor normalviewing.

f.Applythe CAL OUT signatto the RF tNpUTand set the SpectrumAnalyzercontrolsas follows:

FREQSPAN/DV 10 MHz

FREQUENCY100MHz

AUTORESOLNOn

REFLEVEL_2OdBm

MIN RF ATTENOdB

VERTCALDTSPLAY 2 dBiDtv

NARROWVTDEOFTLTER On

VIEWA and VEWB Off

TIME/DIVAUTO

TRIGGERINGFREERUN

g.ActivatezERo spAN and FINE. s€t th€ REFER_ ENCELEVELsuchthat the trace is approximatelymid- screen.

h.Adjustthe Trace RotationR1021(FigureS-2)so the traceis alignedwiththe graticulelines.

i.Activate VIEW A and VIEW B then us€ the PEAK/AVERAGEcursor,positionedat the top thenbot-

tom of the screen, as a reference line to adjust GeometryR1051(FigureS-2)for the straightesttrace at top and bottomof the screen.

5-6

j.Change the REF LEVEL to position the trace withinthe graticulearea with the VerticalDisplaymode of 2 dB/DlV. AdjustINTENSITYso the trace is just visi- ble.

k.Adiust A Intensity R1030 (Figure 5-2) so the brightnessof the readoutcharactersis slightlyhigher than the trace. Readoutcharactersshouldbe just visi- ble after the trace has disappeared.This ratio provides the best settingfor photographpurposes. Disconnect CAL OUTsignalfrom the RF INPUT.

3.Adiust DeflectionAmplifierGain

and FrequencyResponse

(C4057,C4061,C5021,C5104,R1055,andR1066

on the Deflection Amplifiers board)

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When adjustingOption42 instruments,the output of th€ FunctionGeneratormust be connectedto the PENLIFTconnectorat the rearof the instrument,ratherthanas shown in Figure5-4. Be sure to groundpin 1 of the ACCESSORIESconnectorwhen using the PENLIFTconnectorin this manner.

a.Connectthe test equipmentas shown in Figure 5-4. Setthe TIME/DIVto 1 ms.

b.set the Functiongeneratorcontrolsfor a 500Hz sinewavesignal, with an amplitudeof 0 to +4 V, as

viewed on the test oscilloscope. Connect a jumper betweenpins 'land 5 (Ext Video Select and Ground respectively)on the AoCESSoRIESconnector. Deac- tivate VIEW A and VIEW B. and set TRIGGERINGto INT.

c.Adiust Vert Gain, R1066(Figure5-2) for a full screendisplay.

d.Disconnect the 500 Hz signal from the MARKERIVIDEOinput. Removethe jumper between pins 1 and 5 of the ACCESSORIESconnector. Reset Triggerlngto FREERUN.

e.Set TIME/OIV to MNL. Monitor TP2 on the Sweepboard (Figure5-2)with a voltmeter(DigitalMul- timeter). Set the MANUALSCANcontrolfor 0.0 V read-

ing on the voltmeter$P2). Set the horizontalPOSI- TIONcontrolto centerthe CRTbeam(dot).

f.Resetthe MANUALSCANcontrolfor a readingof +5 V at TP2.

g.AdjustHoriz Gain,R1055(Figure5-2)to position the crt beam to the right graticuleedge (10thgraticule line).

h.Reset the MANUALSCANcontrolsuch that crt

beam (dot)moves to the left edge of the graticuleand checkthatthe voltageatTP2is now-5.0V *0.2 V.

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