HP 8560A, Service Manual

Page: 227 / 450

YTO Leveling Loop (334)
This error often requires troubleshooting the Al4 Frequency Control
assembly or A7 LODA (Synthesizer Section) or the ADC circuits.
334 LO AMPL LO Distribution Amplifier is unleveled. This error is usually
accompanied by error codes 300 or 301. ERR 301 YTO UNLK is
cleared once ERR 334 has been cleared. Check the output of the
All YTO with the jumper on
in the TEST position. The
YTO power output should be between and If the
YTO is working properly, refer to “A7 LODA Drive” in Chapter
10. The LODA AGC voltage is monitored by the ADC. ERR 334 is
set if LODA AGC is outside of its prescribed limits. Refer to “A7
LODA Drive” in Chapter 11. Error 334 may also be displayed if the
front-panel LO OUTPUT is not terminated into 50 ohms.
Sampling Oscillator (335)
This error indicates an unlocked Sampling oscillator (also known as
the offset Lock Loop).
335 SMP UNLK Sampling oscillator PLL is unlocked. ERR 335 is set if OFL_ERR is
outside its prescribed limits.
Automatic IF Errors (400 to 599)
These error codes are generated when the automatic IF adjustment
routine detects a fault. This routine first adjusts amplitude
parameters, then resolution bandwidths in this sequence: 300
1
MHz, 100 30 10 3 1 300 Hz, 100 Hz, 30 Hz,
10 Hz, and 2 MHz. The routine restarts from the beginning if a fault is
detected. Parameters adjusted after the routine begins but before the
fault is detected are correct; parameters adjusted later in the sequence
are suspect. Refer to “Automatic IF Adjustment” in Chapter 8.
The IF Section relies on the ADC and video circuitry to perform its
continuous IF adjustments. IF-related errors occur if the ADC, video
circuitry, or A4 assembly linear path is faulty.
400 AMPL 100
401 AMPL 300
402 AMPL
403 AMPL 3K
404 AMPL
Unable to adjust amplitude of 100 Hz Resolution Bandwidth.
Unable to adjust amplitude of 300 Hz Resolution Bandwidth.
Unable to adjust amplitude of 1 Resolution Bandwidth.
Unable to adjust amplitude of 3 Resolution Bandwidth.
Unable to adjust amplitude of 10 Resolution Bandwidth.
Errors 405 to 416: When these resolution bandwidth (RBW) error
messages appear, use the following steps to check for errors 581 or 582.
1. Set the spectrum analyzer (LINE) switch OFF.
2. Set the spectrum analyzer switch ON and observe the lower
right-hand corner of the display for 10 seconds.
6-22 General Troubleshooting