Agilent Technologies 8753ES Option 011 Service Manual page 202

Power Supply Troubleshooting
If the Red LED of the A15 Is ON
• If the red LED goes out, the particular assembly (or one receiving power from it) that
allows it to go out is faulty.
• If the red LED is still on after you have checked all of the assemblies listed in
continue to "Check the Operating Temperature" on page
Table 5-3 Recommended Order for Removal/Disconnection
Assembly To Remove
1. A19 Graphics Processor
2. A14 Frac N Digital
3. A9 CPU
4. A16 Rear Panel Interface
5. A2 Front Panel Interface
Check the Operating Temperature
The temperature sensing circuitry inside the A15 preregulator may be shutting down the
supply. Make sure the temperature of the open air operating environment does not exceed
55 °C (131 °F), and that the analyzer fan is operating.
• If the fan does not seem to be operating correctly, refer to
page 5-19.
• If there does not appear to be a temperature problem, it is likely that A15 is faulty.
Inspect the Motherboard
If the red LED is still on after replacement or repair of A15, switch off the analyzer and
inspect the motherboard for solder bridges and other noticeable defects. Use an ohmmeter
to check for shorts. The +5 VD, +5 VCPU, or +5 VDSENSE lines may be bad. Refer to the
block diagram at the end of this chapter and troubleshoot these suspected power supply
lines on the A17 motherboard.
5-12
Removal or Disconnection
Method
Remove from Card Cage
Disconnect from W14
Remove from Card Cage
Disconnect W36
Remove from cardcage
Disconnect W27
Disconnect W17
5-12.
Other Assemblies that Receive Power
from the Removed Assembly
None
A18 Display
None
A20 Disk Drive
None
None
A1 Front Panel Keyboard A18 Display
"Fan Troubleshooting" on
Table 5-3,
Chapter 5