340 Chapter7
General Troubleshooting
Error Messages
3. If a 10 MHz signal (approximately 0 dBm) is not
present, suspect the A15 RF assembly, the
A21 OCXO, or the A15 assembly TCXO
(Option 103). If the 10 MHz reference is present,
continue with step 4.
4. Reconnect W17 to A4J7 and monitor the tune
voltage at A4J9 pin 3 with an oscilloscope.
5. Press
PRESET on the spectrum analyzer under test.
6. If the voltage is either +15 Vdc or −15 Vdc, the cal
oscillator is probably at fault. Normally, the voltage
should be near +15 V during a sweep, and between
−9 V and +9 V during retrace.
An intermittent error 499 indicates the cal osc
phase-locked-loop probably can lock at 10.7 MHz, but
cannot lock at the 9.9 and 11.5 MHz extremes. This
may prevent the cal oscillator from adjusting the
1 MHz or 30 kHz through 300 kHz bandwidths. This
symptom implies a failure in the oscillator, function
block X. (See the A4 log amp/cal oscillator schematic
sheet 4 of 4.) The oscillator is unable to tune the
required frequency range with the −9 V to +9 V control
voltage. Troubleshoot A4CR802 (most probable cause),
L801, C808, C809, and U807.
500 AMPL 30K Unable to adjust amplitude of 30 kHz resolution
bandwidth.
501 AMPL .1M Unable to adjust amplitude of 100 kHz resolution
bandwidth.
502 AMPL .3M Unable to adjust amplitude of 300 kHz resolution
bandwidth.
503 AMPL 1M Unable to adjust amplitude of 1 MHz resolution
bandwidth.
504 AMPL 30K Unable to adjust amplitude of 30 kHz resolution
bandwidth.
505 AMPL .1M Unable to adjust amplitude of 100 kHz resolution
bandwidth.
506 AMPL .3M Unable to adjust amplitude of 300 kHz resolution
bandwidth.
507 AMPL 1M Unable to adjust amplitude of 1 MHz resolution
bandwidth.
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