Installation guide

Troubleshooting
Troubleshooting Assembly Level Problems
1-44
602 PLL Interface
• Check for A15 Sampler (Option UNJ or Option 506) YO phase lock interference.
a. Disconnect the cable from J4 of the A21 YTO Driver (Option UNJ or Option 506).
— If test 602 still fails, replace the A21 YTO Driver (Option UNJ or Option 506).
(Refer to “A21 YTO Driver (Option UNJ or Option 506) and A22 Coupler (Option 506)” on page 2-50.)
— If test 602 passes, troubleshoot the A15 Sampler (Option UNJ or Option 506).
(Refer to “A15 Sampler (Option UNJ or Option 506)” on page 2-36.)
603 FM Driver
• Measure the FM modulation signal from the A16 Frac-N (Option UNJ or Option 506).
a. Disconnect the cable at J3 of the A21 YTO Driver (Option UNJ or Option 506).
b. Select the FM/ϕM menu.
c. 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
d. Select Mode On/Off to On.
e. Use an oscilloscope and probe the center pin of W28 (the cable that connects to J3 of A21 YTO Driver
(Option UNJ or Option 506)) to measure a 400 Hz square-wave signal with an amplitude > 2 Vp-p.
— If the signal is good, replace the A21 YTO Driver (Option UNJ or Option 506).
(Refer to “A21 YTO Driver (Option UNJ or Option 506) and A22 Coupler (Option 506)” on
page 2-50.)
— If the signal is bad, turn power off and remove the A15 Sampler (Option UNJ or Option 506) and
A16 Frac-N (Option UNJ or Option 506).
a. Ohm the center pin connection between W28 and J14 of the A19 Daughterboard.
This should be a short.
b. Ohm the connection between the center pin of W28 and ground.
This should be an open.
— If the connections are bad, check the W28 cable.
— If the W28 cable is good, replace the A19 Daughterboard.
(Refer to “A19 Daughterboard” on page 2-44.)
— If the connections are good, troubleshoot the A16 Frac-N (Option UNJ or Option 506).