HP 8562E Service Manual page 245

600 MHz Reference Loop (333)
333 600 UNLK
YTO Leveling Loop (334)
334 LO AMPL
Sampling Oscillator (335)
335 SMP UNLK
10 MHz Reference (336)
336 10 MHz Ref
Fractional N PLL (337)
337 FN UNLK
7-26 General Troubleshooting
This error requires troubleshooting the Al5 RF board assembly
(synthesizer section) or the ADC circuits.
The 600 MHz reference oscillator PLL is unlocked. If error codes 302,
303, 304, 327 or 499 are also present, suspect the 10 MHz reference,
the A21 OCXO, or the TCXO (Option 103), or the Al5 RF assembly.
ERR 333 is set if LOSERR is outside of its prescribed limits.
This error often requires troubleshooting the Al4 frequency control
assembly (synthesizer section), the A7 LO distribution amplifier, or
the ADC circuits.
First LO distribution amplifier is unleveled. Error 334 may be
displayed if the front-panel LO OUTPUT is not terminated in 50 0.
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 A14J23 in the TEST
position. The YTO power output should be between +9 and +13
"Al4 Frequency Control Assembly," in Chapter 12, "RF Section."
The LODA AGC voltage is monitored by the ADC. ERR 334 is set
if LODA AGC is outside of its prescribed limits. Refer to "LODA
Drive" under "Al4 Frequency Control Assembly," in Chapter 12, "RF
Section."
This error indicates an unlocked sampling oscillator (also known as the
offset Lock Loop).
Sampling oscillator PLL is unlocked. ERR 335 is set if OFL-ERR is
outside its prescribed limits.
This message occurs during the internal IF calibration routines. The
routine locks the cal oscillator to the internal 10 MHz reference,
regardless of the setting of INT/EXT REF.
Calibration oscillator failed to lock within 5 seconds after going
to internal 10 MHz reference. ERR 336 will not be cleared until a
successful full cal "LO Re-Align" is executed.
This error indicates an unlocked fractional N phase locked loop. This
error only applies to the hardware in an HP 8560 E-Series spectrum
analyzer.
Fractional N circuitry is unable to lock.