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

27.On the oscilloscope press [SHOW].

28.Connect the oscilloscope channel 1 probe to AlA3TP5 using a long probe extension. See Figure 3-7 for the location of AlA3TP5.

29.Reconnect the ac line cords to each instrument section. Adjust the front-panel INTENSITY control fully counter-clockwise, and then set the LINE switch to ON (the INSTR CHECK I LED will light.)

30.Wait approximately 30 seconds for the dc regulator circuits to stabilize again.

31.With the front-panel INTENSITY control fully counter clockwise, adjust AlA2R35 INT LIMIT (clockwise) until a spot is just visible in the lower left corner of the CRT. See Figure 3-8 for the location of the adjustment.

Note The AlA2R35 INT LIMIT adjustment compensates for the variation in beam cut-off voltage of different CRTs and indirectly sets the maximum beam intensity. AlA2R35 INT LIMIT should have enough range to turn the CRT spot on and off. If the spot is always on, decrease the value of AlA2R9. If the spot is always off, increase the value of AlA2R9. Refer to Table 3-3 for the acceptable range of values, and to Table 3-4 for HP part numbers. Refer to Figure 3-8 for the location of AlA2R9.

 

 

R35

 

 

R5

 

R36

I N T

 

 

N T

 

 

I

ASTIG

L I M I T G A I N R9

 

 

I

.//

 

 

 

/

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 3-8. Location of AlA Components

32.Using a non-metallic alignment tool, center the front panel FOCUS control and adjust AlA2R36 ASTIG and AlA3R14 FOCUS LIMIT for a sharp, focused dot on the CRT display.

33.Adjust AlA2R35 INT LIMIT until the dot just disappears.

3-34 Adjustments