Agilent Technologies 856290216 service manual Cal Oscillator Unlock at Beginning of if Adjust

2.If the cal oscillator remains locked (no error code ERR 499 displayed) but does not have the correct output level, troubleshoot the output leveling circuitry (function blocks AA, AB, and AC) or output attenuator (function block AD).

Cal Oscillator Unlock at Beginning of IF Adjust

1.Press (LINEI to turn the HP 85623 spectrum analyzer off and then on. The words IF ADJUST STATUS appear on the display 10 seconds after the instrument is turned on (assuming the rest of the instrument is working correctly). Immediately observe the lower right corner of the display for error messages. If the message ERR 499 CAL UNLK appears (before errors ERR 561, ERR 562 and ERR 565), the cal oscillator is unable to phase-lock. Expect to see the ERR 499 message for only about 1 second.

2.If the HP 85623 spectrum analyzer registers an unlocked cal oscillator, continue with step 3 to verify the presence of externally supplied signals.

3.Check A4U811 pin 9 for a 100 kHz TTL-1 eve1 square wave verifying operation of A4U811, A4Q802, and the 10 MHz input signal from A4J7.

4.Check the +15 VF, +5 VF and -15 V power supplies, and +lO V reference on the A4 assembly.

5.Check that A4U807 pin 5 (CALOSC-OFF) b ecomes TTL low (0 V) at the start of a FULL IF ADJ (press a and FULL IF ADJ ). The phase modulation output at A4U804 pin 8 should also remain at 0 volts. If these checks are correct, troubleshoot blocks V, W, X, and Y. See Figure 9-21, A4 log amplifier/Cal oscillator Block Diagram.

Inadequate CAL OSC AMPTD Range

Refer to function block AC of A4 Log Amplifier Schematic Diagram in the HP 8560 E-Series

Spectrum Analyzer Component Level Information.

1.If A4R826, CAL OSC AMPTD, has inadequate range to perform the IF Amplitude Adjustment, press LCAL).

2.Rotate A4R826 fully clockwise and disconnect W52 (coax 9) from A5J4.

3.Connect A5J4 to the input of a second spectrum analyzer.

4.Set the other spectrum analyzer controls as follows: ~

Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7 MHz Reference level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -30 dBm

5.Observe the spectrum analyzer display while pressing FULL IF ADJ . The signal level should be above -34.55 dBm. If the signal level is incorrect, continue with step 7.

6.Rotate A4R826 fully counterclockwise. The signal should be below -36.25 dBm. If the signal level is correct at both settings, troubleshoot the A5 IF assembly. If the signal level is incorrect, continue with step 7.

7.Troubleshoot the ALC loop on this assembly using the following steps:

a.Connect a positive DVM probe to A4J9 pin 4.

b.On the HP 85623 spectrum analyzer, press (CAL).

IF Section 9-33