E8257D/67D, E8663D PSG Signal Generators Service Guide
Troubleshooting
Troubleshooting Assembly–Level Problems
1-46
1100 Power Supply
The A18 CPU self–test verifies the presence of the supplies listed. These supplies are not checked during the turn–on
check and are not necessary for the turn–on check to pass.
1. After running self–test, View
Details and see which supply failed.
2. If the 10 VRef has failed, replace the A18 CPU. The 10 VRef is generated on the A18 CPU and used for the ADC
circuit.
3. For a self–test failure other than the 10 VRef, measure the appropriate connector pin listed in the following table.
4. If the voltages are present on the A31 Motherboard, turn power off, remove the A18 CPU and inspect the
connector. If the pins look good, replace the A18 CPU.
5. If a supply voltage is not present on the connector, measure the appropriate point listed in the following table:
6. If the voltage is present on P112 but not present on P223, replace the A31 Motherboard.
7. If the voltages are not present on P112, troubleshoot the A9 YIG Driver.
Self–Tests 12xx: A26 MID Self–Test Errors (E8257D)
Connector P223 Supply Voltage Voltage Range
Pin 1 –5.2 Vdc –5.2 ±.1 Vdc
Pin 17 –6 Vdc –6 ±.12 Vdc
Pin 18 +9 Vdc +9 ±.18 Vdc
Connector P112 Supply Voltage Voltage Range
Pin 1, 2, 26, 27 –5.2 Vdc –5.2 ± 0.1 Vdc
Pin 19, 44 –6 Vdc –6 ± 0.12 Vdc
Pin 17, 18, 42 +9 Vdc +9 ± 0.18 Vdc
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