5c-6  
Service Error Messages
611   200 kHz reference missing at synth
Description   The A5 module indicates that the 200 kHz reference signal from the A4 
module is not being detected.
Cause   Either the A4 module has failed to output the 200 kHz reference signal, or 
the A5 module is failing to detect the signal.
What To Do   Check the 200 kHz reference output of the A4 module at the input to the 
A5 module.
612   Reference out-of-lock at 10 MHz
Description   The A4 module indicates that the 10 MHz reference VCO is out-of-lock.
Cause   Either the A4 module has failed or a bad external reference is connected.
What To Do   Disconnect any external reference and power up the instrument again or 
replace the A4 module if the error is still present with no external 
reference.
613   Reference out-of-lock at 1 GHz
Description   The A4 module indicates that the 1 GHz reference is out-of-lock.
Cause   Either the A4 module has failed or a bad external reference is connected.
What To Do   Replace the A4 module.
614   400 Hz modulation source failed
Description   The A3 board indicates that the 400 Hz modulation source is not present.
Cause   Either the 200 kHz reference signal from the A4 module has failed, or the 
A3 has failed.
What To Do   Check the 200 kHz reference output of the A4 module at the input to the 
A3 board.
615   1 kHz modulation source failed
Description   The A3 board indicates that the 1 kHz modulation source is not present.
Cause   Either the 200 kHz reference signal from the A4 modulation source has 
failed, or the A3 board has failed. However, if the 400 Hz modulation 
source has already been tested, the failure is most likely the A3 board.
What To Do   Replace the A3 board.