68 E8257D/67D, E8663D PSG Signal Generators Service Guide
Troubleshooting
Troubleshooting Assembly–Level Problems
702 Tuning Voltage
1. Using an oscilloscope, check 10 MHz Synthesis line on P33–15. The signal
period should be 100 ns with an amplitude of approximately 3V
pp
.
— If the signal is good, replace the A6 Frac–N.
2. If the signal is bad, turn the signal generator power off, remove the A6
Frac–N, and measure the signal at P33–15 again.
— If the signal is good, replace the A6 Frac–N.
3. If the signal is still bad, measure P41–5 on the A7 Reference.
— If the signal is good at P41–5, replace the A31 Motherboard.
— If the signal is bad at P41–5, replace the A7 Reference.
703 Output Voltage
1. Using an oscilloscope, check 10 MHz Synthesis line on P33–15. The
signal period should be 100 ns with an amplitude of approximately 3V
pp
.
— If the signal is good, replace the A6 Frac–N.
2. If the signal is bad, turn the signal generator power off, remove the A6
Frac–N, and measure P33–15 again.
— If the signal is good, replace the A6 Frac–N.
3. If the signal is still bad, measure P41–5 on the A7 Reference.
— If the signal is good at P41–5, replace the A31 Motherboard.
— If the signal is bad at P41–5, replace the A7 Reference.
704 Filter Test
1. Refer to Table 1-13, and check J1 on the A6 Frac–N:
a. Turn the signal generator on and remove the A6 Frac–N.
b. Set the signal generator to the first center frequency.
c. Use an extender board cable to connect a spectrum analyzer to J1.
d. Tune the spectrum analyzer to the first J1 frequency, and check for
the correct power.
e. Repeat Step d for the remaining frequencies.
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