Agilent Technologies 8648A Operation And Service Manual page 237

−12 V power supply failure
601
The −12 V diagnostic test point decreased by more than approximately
Description
0.4 V.
Either the −12 V regulator on the A3 motherboard has failed, or the −15 V
Cause
supply on the A2 power supply assembly has failed.
Check the output of both the −15 V and −12 V supplies.
What To Do
603
+12 V power supply failure
Description The +12 V diagnostic test point decreased by more than approximately
0.4 V.
Cause Either the +12 V regulator on the A3 motherboard has failed, or the +15 V
supply on the A2 power supply assembly has failed.
What To Do Check the output of both the +15 V and +12 V supplies.
604
+38 V power supply failure
Description The +38 V diagnostic test point decreased by more than approximately
2.2 V.
Cause The +38 V supply on the A2 power supply has failed.
What To Do Check the +38 V supply.
605
ALC out-of-lock div het main band
Description The ALC loop is out of lock in the indicated bands.
Cause Either the A6 output has failed, or the signal from the A5 synthesizer has
failed or the A4 reference has failed. If only the het band has failed it is
possible that the A4 reference has failed.
What To Do Check the input to the A6 output from the A5 synthesizer and the A4
reference.
608
Synth out-of-lock div het main band
Description The synthesis loop is out of lock in the indicated bands.
Cause Either the A5 synthesizer has failed, or the signal from the A4 reference
has failed.
What To Do Check the input to the A5 synthesizer from the A4 reference.
Service Error Messages
5c-5