Keysight Technologies E8257D Service Manual page 53

Troubleshooting
Troubleshooting Assembly–Level Problems
Symptom: Amber front panel LED blinking
Thermal shutdown
With thermal shutdown, the front panel green LED and the power supply LEDs
blink as long as the condition exists. There are two temperature sensing
devices in the instrument: one on the A8 Output, and one on the A19 Power
Supply.
To troubleshoot:
1. If the instrument is hot, ensure that the fan is working and let the
2. If the instrument still shuts down, remove the Output assembly.
3. If the instrument still shuts down, replace the Power Supply.
Symptom; +9, –6, or –5.2 V LEDs not on
Troubleshoot using the
page
1. At P112 of the Motherboard, ensure the YIG Driver Assembly is receiving
2. If the supplies are present at P112, note in the matrix where each supply is
3. Power down the instrument and remove one of the assemblies that is
4. Power the instrument up again and check the faulty supply. If it is still bad,
5. Remove the next assembly and see if that fixes the problem. Continue this
6. Replace the last assembly that you removed.
Symptom: +1.95 VD, +1.8 VD LEDs not on
These supplies are generated by voltage regulators on the A31 Motherboard.
Troubleshoot by checking the following voltages at the A19 Power Supply:
— +3.4 VD, which is regulated down to +1.95 VD
— +2.6 VD, which is regulated down to +1.8 VD
If the supplies are good at the A19 Power Supply, replace the A31
Motherboard.
E8257D/67D, E8663D PSG Signal Generators Service Guide
instrument cool off.
or
If the instrument powers on, but the amber LED continues to blink, replace
the A3 Power Switch assembly.
These supplies are generated on the YIG Driver Assembly.
Power Supply vs. Assembly Matrix
1-37.
the +32, +15, +10, –7, –15 Vdc supplies.
used.
biased by the faulty supply.
power down and re–install the first assembly removed.
process until the supply functions properly.
that begins on
53