74 E8257D/67D, E8663D PSG Signal Generators Service Guide
Troubleshooting
Troubleshooting Assembly–Level Problems
Self–Tests 10xx: A7 Reference (Option UNR/UNX and Instruments
with Serial Prefixes ≥ US4805/MY4805) Self–Test Errors
Before proceeding to the reported self–test error code, check the following
voltages. If any voltages are out of specification troubleshoot the supply
problem first.
1000 Power Supply
— Replace the A7 Reference.
1001 10 MHz Test
1. Using an oscilloscope, check P41–2 for a 10 MHz signal greater than 1.12
V
p–p
. If the signal is present, replace the A7 Reference.
2. If the signal is not present, the problem could be the 10 MHz Reference or
the signal path from the 10 MHz Reference.
Supply Voltage
(Vdc)
Connector Pins Minimum Value
(Vdc)
Maximum Value
(Vdc)
Origin
+15 P42–6, 21 +14.55 +15.45 Main Supply
–15 P42–2, 17 –14.55 –15.45 Main Supply
+9 P42–5, 20 +8.82 +9.18 YIG Driver
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