Service manual

46 Servicing the Mainframe Chapter 3
Problem Isolation
Table 3-2 lists primary mainframe symptoms, possible cause(s), and
suggested actions. Table 3-1 shows replacement part numbers.
Replacing Mainframe Components
This section gives guidelines to replace E8408A mainframe components,
including:
• Removing Mainframe Accessory Items
• Removing the Mainframe Cover
• Replacing the Power Supply Assembly
• Replacing the Monitor Board
• Replacing the Fan Assembly
• Replacing the Front Panel Tapped Strip
• Replacement Power Cords
Table 3-2. Isolating Problems in the E8408A Mainframe
Symptom Possible Cause Action
No mainframe
power
Power Supply fuse blown
or defective Power Supply
- There are NO replaceable power line fuses on mainframe.
- If the mainframe power supply fails to operate, replace the
Power Supply Assembly.
Short between some
supplies can latch the
Power Supply OFF
- Switch to Standby mode, and then remove AC power.
- Recovery can occur when AC power is reapplied and the
mainframe Power switch is switched to ON.
- If problem remains, replace Power Supply Assembly.
Flashing Voltages
Indicator
Backplane voltage(s) may
be incorrect
- Cycle mainframe Power switch.
- Remove VXI instruments to ensure they are not the cause.
- Check cable connections at Monitor and Backplane Board.
- Replace Power Supply Assembly.
Flashing Temp
Indicator
Power supply temperature
is high.
- Mainframe is nearing automatic shutdown.
- Check for proper air flow and clearance around the fan.
- Check power requirements of installed VXI instruments.
- Replace Fan Assembly as required.
- Replace Power Supply Assembly as required.
Flashing Fan
Indicator
Fan has failed or fan
connection loose
- Turn off mainframe to avoid possible overheating.
- Check fan connections to P3 on Backplane Board.
- Replace Fan Assembly as required.
Monitor indicators
and fan remain
OFF when Power
switch is pressed.
Defective Monitor Board
(E8408-66502) or loose
cable to Monitor Board
- Check cable connections at Monitor and Backplane Board.
- Replace Monitor Board as required.
Slot 0 Card
SYSFAIL
Indicator
VXI Instrument failure - The Slot 0 card (E1406A, E8491A, etc.) SYSFAIL
indicator will turn ON and remain ON when a VXI
instrument installed in the mainframe fails.