2.High-Voltage Adjustment (SN 3001A and Below)

39.Slowly adjust the front-panel INTENSITY control through its entire range while monitoring the peak-to-peak voltage at AlA3TP5. As the INTENSITY control is turned clockwise, the peak-to-peak voltage at AlA3TP5 will drop. To prevent long-term CRT damage, this voltage should not drop below (V,, - 5O)V,., or 12 VP-,,, whichever is greater. See Figure 3-10. (The value of V,, was recorded in step 34.)

If the front-panel INTENSITY control cannot be set fully clockwise without dropping below this minimum peak-to-peak voltage, then perform the following:

a.Set the INTENSITY control fully counter clockwise.

b.Set the LINE switch to STANDBY.

c.Increase the value of AlA2R9.

d.Return to step 34.

Note Maximum CRT life expectancy is obtained when the peak-to-peak voltage at AlA3TP5 is as large as possible with the INTENSITY control set fully clockwise. The display illumination must fully disappear with the INTENSITY control set fully counter clockwise.

5 0 . 0 uS/dlv

1 f 85.00 v

Figure 3-10. Waveform at AlA3TP5

40.Replace the cover on the AlA High-Voltage Regulator Assembly.

41.The High-Voltage Adjustment is completed. If an AlA2, AlA4, or AlA assembly has been repaired or replaced, perform adjustment procedure 3, “Preliminary Display Adjustment (SN 3001A and Below)“, and then adjustment procedure 4, “Final Display Adjustments (SN 3001A and Below)“. If the AlA2,

3-36 Adjustments