E8257D/67D, E8663D PSG Signal Generators Service Guide 59
Troubleshooting
Troubleshooting Assembly–Level Problems
4. If the supply voltages are bad at the origin, troubleshoot the problem
using that assembly’s troubleshooting procedure.
201 Tuning + Bias Test
1. Turn power off and remove the A5 Sampler and connect a signal analyzer
to the A5 Sampler J1 input cable on the A31 Motherboard.
2. Turn the signal generator on and check for the presence of a 1 GHz signal
at the level of 0 dBm.
3. If the signal is good on the cable connector J1, replace the A5 Sampler.
4. If the signal is bad, remove the A7 Reference and ohm the cable between
the center pins (a short should occur) and between the center pins and
shielding (an open should occur) of J3 on the A7 Reference and J1 on the
A5 Sampler.
5. If an open is measured between the center pins or a short between center
pins and the shielding, replace the cable.
6. If the cable is good, replace the A7 Reference.
202 Coarse Loop Detector
1. Replace the A5 Sampler
203 YO Loop Detector
1. With power on carefully remove the A5 Sampler, connect a signal analyzer
to J3 on the A31 Motherboard. Set the signal generator to 8 GHz CW then
check for an 8 GHz signal at a power level greater than or equal to –7 dBm
on J3.
2. If the J3 signal is bad, troubleshoot the A29 20 GHz Doubler using the
procedure in the RF path section. If the J3 signal is good, go to the next
step.
3. Connect the signal analyzer to the A6 Frac–N VCO signal on the J6
connection on the A31 Motherboard. With the signal generator set to
8 GHz CW, the A6 Frac–N signal should be at a frequency of 593.75 MHz
and at a power level of +7 dBm.
4. If the signal is good, replace the A5 Sampler, if the signal is bad go to the
A6 Frac–N troubleshooting procedure.
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