E8257D/67D, E8663D PSG Signal Generators Service Guide 75
Troubleshooting
Troubleshooting Assembly–Level Problems
3. Check the 10 MHz reference oscillator output signal.
a. If the 10 MHz signal is not present on the output port, measure the
10 MHz power supply voltages on the rear panel interface board.
The following voltages should be observed:
— Pin 1 ground
— Pin 2 +12V
— Pin 3 ground
— Pin 4 a positive DC voltage around +3.8V should be present (oven
cold raw voltage may vary).
b. If the power supply voltages are good, replace the 10 MHz
reference.
c. If the power supply voltages are bad, replace the rear panel
interface board.
4. If the 10 MHz signal is present out of the reference oscillator, but not on
the A31 mother board at P41–2, reconnect the cable going to the 10 MHz
signal.
a. Measure the end of the cable going to the A31 mother board at
J1041.
b. If the signal is bad, replace the cable.
c. If the signal is good, go to Step 5.
5. Measure the ohmic resistance between the J1041 center pin and P41–2
and the J1041 center pin to ground.
a. If the trace is open or shorted to ground, replace the A31 mother
board.
b. If the J1041 is not shorted to ground and the J1041 to P41–2 is not
open, remove the A7 board and measure P41–2.
c. If the signal is now present, replace the A7 board.
d. If the signal is still missing, replace the A31 mother board.
1002 1 GHz Test
— Replace the A7 Reference.
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