Installation guide

Troubleshooting
Troubleshooting Assembly Level Problems
1-36
400 Ground and PTAT Test
• Using a DVM, measure the voltages on J10 (the PTAT voltage is derived from the ± 15 Vdc):
— If the supply voltages are good on the J10 connector pins indicated:
a. Turn off the power and remove the A13 Output.
b. Ohm the connection between the appropriate pins of J12 and J10.
— If the connection is good, replace the A13 Output.
(Refer to “A13 Output” on page 2-32.)
— If the connection is bad, replace the A19 Daughterboard.
(Refer to “A19 Daughterboard” on page 2-44.)
— If the supply voltages are bad on any of the J10 connector pins indicated:
a. Check the origin of the supply.
— If the supply voltages are good at the origin, replace the A23 Motherboard.
(Refer to “A23 Motherboard” on page 2-52.)
— If the supply voltages are bad at the origin, troubleshoot the problem using that assembly's
troubleshooting procedure.
401 Prelevel Loop Test
CAUTION Do not install the A13 Output with the signal generator powered up or serious damage to the
signal generator may be caused.
• With the signal generator powered up, carefully remove the A13 Output from the signal generator.
• Set the signal generator to a frequency of 900 MHz.
• At J4 of the A13 Output, connect a spectrum analyzer to the A16 Frac-N (Option UNJ or Option 506) or
A17 Synthesizer (Option 501, 502, 503, 504) RF output and measure the signal; it should be 900 MHz at
an amplitude ≥ 5 dBm.
— If the signal is not present or at the correct amplitude, refer to the A16 Frac-N (Option UNJ or Option
506) or A17 Synthesizer (Option 501, 502, 503, 504) troubleshooting.
— If the signal is present, replace the A13 Output.
(Refer to “A13 Output” on page 2-32.)
402 Quadrature DAC Test
• Replace the A13 Output.
403 VBLO Test
• Replace the A13 Output.