Tektronix 494AP O o o o o o o o o o o o o o o o o o o o o o o o o, Rrqm, Time/Div Mnl

o o o o o o o o o o o o o o o o o o o o o o o o o o o

2. ^qlult Z-AxisandHighVotrageCircuits R1027,Rlogo,-R1ost,tno-ili0s8

{110?1,onthe Z-Axis board; R2O4Aand R3030on the HighVottage board)

a.Switch POWER off and preset the foilowing SpectrumAnatyzercontrols:

INTENSITY FullyCounterclockwise

TIME/DIV MNL

MANUALSCAN Midrange

b. Removethe cover over the Z-Axis and Sweep boards. Set the IntensityLimit R1027.on fi," Z_Axis

5-2) fuily counterctockwise

Plr.l(FigureanOCrt Bias 12010,.on rhe High Vo[age board figure 5_3)fuily clockwise.

c. SwitchPOWERon-and,afterthepower-upstatehas stabilized,chang_ethe Vertical OiJpf"V mode to 2 dBlDtv. DeactivatehEADOUT,

viEw l,'""0 vtEWB.

d. AdjustCrt Biasas follows:

(1)Using a voltmeterin the 20 V range,measure and recordthe collectorvoltageof a+06e or e4059 on the Z-Axisboard(SeeFiguie5-1b.)

(2)Turn the INTENSITyclockwiseuntil a crt beam dot appearson screen.

(3)Focus the dot by adjustingRgoggon the High v€ttage board (Figures_3)toi tne smailestround dot.

Adjustment Procedure- 494A/494ApServiceVot. 1

(4) Set the INTENSITYcontrolsuchthat the voltage at the coltectorof e4059 is 5.5 V higher than the voltagenotedin part d, subpart1.

(5) Use the non-metallicscrewdriverto adjust Crt Bias, R2040,counterclockwiseuntil the crt beamis visible,then clockwiseuntilthe beamdot just extin- guishes, with the scr€en shaded. (f no dot 1?pea.tj:with the adjustmentfuilycounterctockwise, this will be the biassetting.)

(6)Turn the tNTENStTyctockwiseuntila dot is visi_ ble then defocusth€ dot with thEFocusadjustment, R3033. AdjustAstigmatismR1OS8(Figurel5*lZltora round dot then refocus with R3033for ttre smailest and sharpestdot.

fl) Turn the tNTENStTycounterclockwise untit the

dot just disappears,and againmeasurethe collector voltageat Q4058or e4059. Vottageshoutdequator exceedthat set in part d, subpart4. ll the voltageis less,repeatthe procedurefor settingCrt bias.

e. Adjustthe Crt cathodecurent as follows:

(1)Switch POWERoff, then removep4096(Figure 5-3) on the High Vottageboard. Turn NTENSIW fully clockwise,MANUALSCAN fuily counterclock_ wise, and ensurethat the TIME/DIVis in the MNL position. S€t the IntensityLimit R1022,on the Z_ Axis board,(Figure5-2)fuilyclockwise.

(2)Connectthe voltmeterbetweenTp402g(Figure 5-3)and the groundlug on the crt shietd.

ASTmAnSt

Rr058

o o o o o o o o o o o o o o o o o

GEOTETRY

A D{TEilSTY Rr051

Rrqm

SWEEP

ACCURACY

R1002

POUER	YERTICAL GAIN
STATUS	RlOGO

Figure 5-2.Crt display adjustment and test point locaiions.

5-5