Service manual

5 127
Power Supply Troubleshooting
FIND OUT WHY THE A50 SHUTDOWN LED IS OFF
5. Power Supply Troubleshooting
FIND OUT WHY THE A50 SHUTDOWN LED IS OFF
Use this procedure when the fan is rotating. If the fan is not rotating, see FIND OUT WHY
THE FAN IS NOT ROTATING.
If the fan is rotating and the A50 SHUTDOWN LED is off, the problem may be in the A50
DC-DC Converter and any of assemblies obtaining the power from +5 VD supply and the
higher power supplies.
1. Disconnect the Cable from the A50P3
Turn the analyzer power off. Disconnect the cable from A50P3. Turn the analyzer power
on.
• If the A50 SHUTDOWN LED goes on, continue with FIND OUT WHY THE A1 +5VD
LED IS NOT ON STEADILY.
• If the A50 SHUTDOWN LED is still off, the A1 CPU is verified. Turn the analyzer
power off and reconnect the cable to the A50P3. Continue with Remove A50.
2. Remove A50
1. Turn the analyzer power off.
2. Remove the A50 from the A20 motherboard. The cable from the A50P2 and the cable
from the A50P3 are connected.
3. Turn the analyzer power on.
• If the A50 SHUTDOWN LED is still off, replace the A50 DC-DC Converter.
• If the A50 SHUTDOWN LED goes on and Five LEDs go on, the A50 is verified.
Reinstall the A50. Continue with the next step.
3. Remove Assemblies
1. Turn the analyzer power off.
2. Remove the assemblies A2, A3, A4, A5, A6, A7, and A8.
3. Turn the analyzer power on.
• If the A50 SHUTDOWN LED is still off, inspect the A20 motherboard for
soldering bridges and shorted traces on the FAN POWER and the FAN LOCK
signal paths.
• If the A50 SHUTDOWN LED goes on, the A20 motherboard is verified. Continue
with the next step.
4. Reinstall each assembly one at a time. Turn the analyzer power on after each is
installed. The assembly that causes the A50 SHUTDOWN LED to go off is the most
probable faulty assembly. Replace the assembly.