Cal Oscillator Unlock At Beginning Of If Adjust; Inadequate Cal Osc Amptd Range - HP 8560A Service Manual

Cal Oscillator Unlock at Beginning of IF Adjust

1. Turn the spectrum analyzer luNE) switch off and then on. The words
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
561, 562 and 565), the cal oscillator is unable to phase-lock. Expect to see the
message for only about 1 second.
2. If the 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-level square wave verifying operation of A4U811,
4. Check the $15 VF, i-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 (CAL) and FULL IF
should also remain at 0 volts. If these checks are correct, troubleshoot blocks V, W, X, and
Y. See Figure 8-23, Cal Oscillator Block Diagram.

Inadequate CAL OSC AMPTD Range

Refer to function block AC of A4 Calibration Oscillator Schematic Diagram in the
HP 856OA/61B/63A 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7MHz
Reference Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -30 dBm
5. Observe the spectrum analyzer display while pressing
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 spectrum analyzer press ICAL).
FULL IF ADJ
Press
ADJUST STATUS: 300 kHz RBW
period, the voltage should be within a 2 to 10 Vdc range.
d. Observe the DVM reading while
reading should be within the 2 to 10 Vdc range.
ERR 499 CAL UNLK
ADJ
. Observe the DVM reading between the displayed messages
IF ADJUST STATUS: 3 kHz RBW.
and
IF ADJUST STATUS: AMPLITUDE
IF ADJUST STATUS
appears (before errors ERR
binder.
FULL IF ADJ
. The signal level
Duringthistime
is displayed. The
IF Section 8-35
ERR 499
IF