Installation guide

Troubleshooting
Troubleshooting Assembly Level Problems
1-49
706 FM Path Test
• Measure the FM modulation signal from the A18 Reference.
a. Turn power off to the signal generator.
b. Remove the A16 Frac-N (Option UNJ or Option 506) and insert a ribbon cable extender
1
into J41 of the
A19 Daughterboard.
c. Turn power on to the signal generator.
d. Select the FM/ϕM menu.
e. Select the following:
—FM mode
—FM Path 1
— FM Dev 100 kHz
— FM Source (Internal)
— FM Rate 400 Hz
— More (1 of 2) >> FM Waveform (Square)
—FM On
f. Select Mode On/Off to On.
g. Use an oscilloscope and probe pin 11 of the ribbon cable extender to measure a 400 Hz square-wave
signal with an amplitude > 4 Vp-p.
— If the signal is good, replace the A16 Frac-N (Option UNJ or Option 506).
(Refer to “A16 Frac-N (Option UNJ or Option 506)” on page 2-38.)
— If the signal is bad, turn power off and remove the A18 Reference.
(Refer to “A18 Reference” on page 2-42.)
a. Ohm the connection between J41-11 and J53-11 of the A19 Daughterboard.
This should be a short.
b. Ohm the connection between J41-11 and ground.
This should be an open.
— If the connections are bad, replace the A19 Daughterboard.
(Refer to “A19 Daughterboard” on page 2-44.)
— If the connections are good, troubleshoot the A18 Reference.
1. The ribbon cable extender needs to be assembled by the user. It consists of two connector plugs
(part number 1252-1010) and approximately eight inches of ribbon cable (part number 8120-2226).
The ribbon cable contains 26 wires; six of these wires need to be stripped off before being connected
to the plugs.