Agilent Technologies J-BERT N4903B, User Manual, Page: 515 / 572

Then the oscilloscope should show an output eye like the following:
If you see a display like above everything is OK.
If you cannot see a clear eye diagram, then check if the N4876A is connected
properly to the Serial BERT. The N4876A must be connected to Data Out, Aux Data
Out and Aux Clk Out to work properly.
If the connection to the Serial BERT is setup correctly, then check the output signal
of the Serial BERT at the Data Out, Aux Data Out (both should show a eye diagram
with an offset of -400mV and a amplitude of 800mV). Check the output signal of
Aux Clk Out, it should give a clock signal of set set data rate with an offset of 0V
and an amplitude of 400mV. if one of the used Serial BERT outputs is not providing
the expected signal, then the Serial BERT is defective.
If the Serial BERT is providing the correct signals, then connect the N4876A again
and run the adjustment procedure from the
Config
screen. Check the output of the
N4876A again after the adjustment has been done.
If the adjustement does not fix the problems, then the N4876A is defective.
Check the Output of the N4876A Multiplexer Using the Error
Detector
If you have connected the N4876A to a Serial BERT and have no oscilloscope at
hand, you can use the error detector for checking the output of the N4876A.
1 Connect the ED Data-In to the Data-Out of N4876A
2 Connect the ED CLK-In to the PG-CLK Out
Solving Problems
9
Agilent J-BERT N4903B High-Performance Serial BERT 515