315 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, A14U116, or A14QlOl. This error message appears when the roller Span Attenuator DAC is out of range. This DAC value is recalculated each time there are changes to the span or start frequency. ERR 315 is set if this value is less than 10 or greater than 245.
316 FREQ ACC Sensitivity of main roller pretune DAC is 0. Once the main roller is locked, the MAINSENSE voltage is measured and the pretune DAC value is incremented by two. ERR 316 is set if the difference between the new MAINSENSE voltage and the previous MAINSENSE voltage is 0.
YTO Loop Errors (317 to 318)
These messages indicate that the YTO Main Coil Coarse DAC (ERR
317)or fine DAC (ERR 318) is at its limit. If error codes 300 or 301 are not present, a hardware problem exists in the YTO loop but the loop can still acquire lock. Refer to Chapter 10 to troubleshoot the YTO PLL. The ADC circuit on the A3 Interface assembly may also cause this error.
317 FREQ ACC Main coil coarse DAC at limit. The main coil coarse DAC is set to bring YTO ERR close enough to 0 volts for the main coil fine DAC to bring YTO ERR to exactly 0 volts. ERR 317 is set if the main coil coarse DAC is set to one of its limits before bringing YTO ERR close enough to 0 volts.
318 FREQ ACC Main coil fine DAC at limit. The main coil fine DAC is set to bring YTO ERR to 0 volts after the main coil coarse DAC has brought YTO ERR close to 0 volts. ERR 318 is set if the main coil fine DAC is set to one of its limits before bringing YTO ERR to 0 volts.
Roller Oscillator Errors (321 to 329)
These errors indicate a faulty roller oscillator on the Al4 Frequency Control assembly. Refer to Chapter 10. The A3 Interface ADC circuits may also be faulty. If error codes 333 and 499 are also present, suspect the 10 MHz Reference, the A21 OCXO, or the Al5 assembly (Option 103).
321 FREQ ACC Main roller tuning sensitivity is not greater than 0. The MAINSENSE voltage is noted in a locked condition and the main roller is programmed to a frequency 400 kHz higher. ERR 321 is set if the new MAINSENSE voltage is not greater than the previous MAINSENSE voltage.
322 FREQ ACC Main roller pretune DAC value set greater than 255. During the LO adjust sequence, the main roller is locked and then programmed to a frequency 1.6 MHz higher. A new pretune DAC value is calculated based upon the main roller tuning sensitivity. ERR 322 is set if this calculated value is greater than 255.