Tektronix 494AP service manual O a o o O o o a o, Adjustment procedure 4g4Al4g4ApseMce vot

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Adjustment procedure - 4g4Al4g4ApseMce vot. 1

Calibrato. Level

R1045 in 3rd Converter

lF Gain R1015 10 ltlHz lF Ampl

Tll 5O3llain Frame

10 dB and 1 dB Step Attenuators

Figure5-20- lF gain test setup,and adjustnent and conn€ctor rocason3-

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12.Adjust B-SAVE A Reference Level (S1015on the VerticatDigitatStorageboard)

when B-sAVEA is selected,the expressionimple- mentedis (B-sAVEA) + kl, where k is'aconstantset by the input data for an g-to-4line encoder,u1015. Eachbit will move the referencelevel about 0.2 minor division. Normally,the referencelevel is set at the centergraticuleline; however,it can be set anywhere withinthe graticuteare3!y the settingof an g_biibinary switch,S1015(Figure5-7). The MSB (switch#8) shifti the display about five divisions,swiich #7 h;lf this amount,etc. The followingproceduresets the refer- encelevel.

Estimatethe amount and directionthe reference level is to be shifted,then close or open the switches on 31015 to obtain the desired B-SAVEA reference level.

13. Adjust Preselector Driver

(Rl031, Rl045, Rl049, Rl052, R10s4, Rl056,

R1061,R1063,R1064,R1065,and R2066on the

Preselectordriverboard)

a.Connectthe test equipmentas shownin Figure

5-21.

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