Operation 26
CG635 Synthesized Clock Generator
PRBS Off
Run/stop state
Running
Display Frequency
Display on/off state
On
Enabled remote interface
RS-232
GPIB address
23
Power-on Status Clear (*PSC)
1
Troubleshooting
The CG635 does not include any user serviceable parts inside. The line fuse is internal to
the instrument and may not be serviced by the user. In the event of instrument failure,
refer service to a qualified technician.
The CG635 performs several instrument tests during startup. The tests are described in
Table 16. In most cases the unit will have to be repaired by a qualified technician if the
unit fails one of these tests.
Table 16: Power-On Self Tests
Test Description
Test
Fail
Symptoms
ROM ROM checksum
Flash memory is corrupted. Unit may behave
unpredictably
1
24V Power
Power supply is not providing stable 24 volts.
2
19.44 MHz tuning
The crystal can’t tune to ±100 ppm. The CG635
may not be able to lock at all frequencies.
3
19.40 MHz tuning
The crystal can’t tune to ±100 ppm. The CG635
may not be able to lock at all frequencies.
4
RF VCO
The VCO can’t tune from 960MHz to 2.05 GHz.
The CG635 may not be able to lock at all
frequencies.
5
CMOS output
The CG635 is unable to drive the front-panel
CMOS output to the correct voltage. Check that
the output is not connected to a voltage source.
6
Q / Q
¯ outputs
The CG635 is unable to drive the Q / Q
¯ outputs to
the correct voltages. Check that the outputs are
terminated into 50
ȍ
and not connected to a
voltage source.
7
Clock symmetry
Output duty cycle is not 50 %. Output driver is
likely damaged.
8
Option detection
Optional oscillator is installed, but not oscillating.
The CG635 will use its internal oscillator.
Table 17 contains a list of troubleshooting tips for various symptoms which may occur in
a normally functioning unit. Please consult this list before contacting SRS regarding a
potential instrument failure.
