HP 8560A Service Manual page 224

307 FREQ ACC
308 FREQ ACC
309 FREQ ACC
frequency. The offset oscillator pretune DAC is set to provide a
frequency less than 294 MHz while the PLL is programmed for 204
310 FREq ACC
is incremented until MAINSENSE changes polarity. ERR 310 is set
if the DAC is set to 255 before MAINSENSE changes to a negative
polarity.
311 FREQ ACC Main roller pretune DAC set to 255. The main roller pretune DAC is
set to 5, causing MAINSENSE to go to the positive rail. The DAC
is incremented until MAINSENSE changes polarity. ERR 311 is set
if the DAC is set to 255 before MAINSENSE changes to a negative
polarity.
312 FREQ ACC Unable to adjust MAINSENSE to 0 volts using the fine adjust DAC.
The coarse adjust and fine adjust DAC are used together to set
MAINSENSE to 0 volts with the loop opened. ERR 312 is set if the
fine adjust DAC cannot bring MAINSENSE to 0 volts.
Error in LO synthesis algorithm. ERR 313 is set if a combination of
313 FREQ ACC
Sampler oscillator and roller oscillator frequencies could not be found
to correspond to the required YTO start frequency. Contact the
factory.
314 FREQ ACC Indicates problems in the span calibration. Troubleshoot any unlocks
before attempting to troubleshoot span calibration problems, because
the loops must all lock in order to perform the calibration. If LO
spans greater than 1 MHz are correct, check A14U114B , A14U115A,
roller oscillator sweep sensitivity is 0. A sweep ramp is injected into
the locked main roller loop which should generate a negative-going
ramp on MAINSENSE. ERR 314 is set if the slope of this ramp is 0.
This is an indication of an unlocked main roller loop or lack of a sweep
ramp.
Transfer oscillator pretuned DAC out of range. The transfer oscillator
pretune procedure attempts to find pretuned DAC values by
programming the PLL to 25 different frequencies and incrementing
the transfer oscillator pretune DAC until XFRSENSE changes
polarity. ERR 307 is set if the DAC is set to 255 (maximum) before
XFRSENSE changes polarity.
Offset oscillator pretune DAC not within prescribed limits at low
frequency. The offset oscillator pretune DAC is set to provide a
frequency less than 189 MHz while the PLL is programmed for 189
MHz. ERR 308 is set if XFRSENSE is greater than i-5 V (it should
be at the negative rail).
Offset oscillator pretune DAC not within prescribed limits at high
MHz. ERR 309 is set if XFRSENSE is greater than +5 V (it should
be at the negative rail).
Main roller pretune DAC set to 255. The main roller pretune DAC is
set to 5, causing MAINSENSE to go to the positive rail. The DAC
General Troubleshooting 6-19