Chapter 4 59
Troubleshooting
No Display troubleshooting
4. Troubleshooting
Step 1. Check fan operation and DC monitor LED
If the rear panel fan (blower) doesn't run, a failure in power supply is assumed. Remove the
E5052B outer cover and check if the following LEDs light:
• +3.3 V and +5 V dc monitor LEDs on A21 PCI DSP card
NOTE To check all the outputs of the power supply, measure the dc voltages at the output lead
connectors with a DMM. The dc output voltages and lead color information is provided in
the module cover label of the power supply.
To check all the outputs of the A22 power distribution board, measure the dc voltages at
the voltage test pins with a DMM.
Step 2. Check system fans inside.
If the system fans on the chassis inside the E5052B don't run, problem seems in the A22
power distribution board. In this case, remove the E5052B outer cover and make sure
whether the fans run or not.
NOTE If the power shutdown occurs without a beep, the problem seems in the A22 power
distribution board ro the A20 digital motherboard assembly. Check BIOS status of A20
digital motherboard assembly is correct as described in “To configure the A20 Digital
Motherboard and BIOS” on page 81.
Step 3. Checking with the external monitor
Connect an external XGA monitor to the VIDEO output on the E5052B rear panel.
• If something is displayed on the external monitor, the problem is present around the
A51 LCD. Also check the A21 PCI DSP card and A22 front panel keyboard because
the ON/OFF setting of the A51 LCD backlight is controlled by the A21 through the
A22.
• If nothing is displayed even on the external monitor, the problem seems in the A20
digital motherboard.
Step 4. Checking flat cable
Check a flat cable between the A20 digital motherboard and A22 front panel keyboard.
Step 5. Check around the backlight
Check A52 inverter board and a cable between the A52 and A22 front panel keyboard.
Also check the cables between the A51 LCD and A52. If the cables are normal, check the
A51 LCD.
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