Agilent Technologies 856290216 service manual Display/Power Supply -l

Note	The	following	measurements should be		made with a high-voltage probe, such
	as	the HP 34111A.		When using the high-voltage probe, connect the ground
	lead	securely	to the	spectrum analyzer	chassis.

7.Carefully measure the grid voltage at A17J7 pin 6, and the cathode voltage at A17J7 pin 4. The display will work with a cathode voltage of -2450 V f250 V, provided the grid voltage (A17J7 pin 6) is 30 to 100 V more negative than the cathode. A17Rl1, CUTOFF, should be able to adjust the voltage difference over a 60 V range to account for tube variations, and achieve proper intensity.

8.If the grid and cathode voltages are correct, turn off the spectrum analyzer and check CR10 with an ohmmeter. If CR10 is good, suspect the A18Vl CRT.

9.If the grid and cathode voltages are too low, turn off the power and disconnect W8 from the base of A18Vl CRT, and recheck the grid and cathode voltages.

10.If the grid and cathode voltages are still too low, refer to “CRT Supply” in this chapter and the “High-Voltage Power Supply Adjustment” procedure in Chapter 2, “Adjustment Procedures.”

11.If voltages are correct when the tube is disconnected, the CRT is probably defective.

Caution The pins on the A18Vl CRT bend easily. Be careful not to bend pins when connecting W8 to A18Vl.

Display/Power Supply Section 13-l 1