Technical data

4-66 Fault Isolation
4. If the dc output voltages are present at J004, but not within tolerance, perform
the following six steps:
A. Power off the system and unplug the ac power cord from the wall outlet.
Replace the power supply.
B. If the problem persists, you must check for power loading. Power off the
system and unplug the power cord from the wall outlet. Remove one option
board (graphics, network, or HP-IB) from its board slot (refer to Chapter 5
for information about removing the board). Plug the power cord into the ac
wall outlet and power on the system. Recheck the voltages. If necessary,
repeat this procedure for a second option board. If you replace a defective
board, configure any switches or jumpers the same as on the original board
(refer to Appendix B).
C. If the cause of the problem isn’t an option board, power off the system and
unplug the power cord from the ac outlet. Reinstall the board(s) in its slot.
D. Unplug connector P2 from the disk drive. Power on the system unit and
recheck the voltages. If necessary, repeat this step on a second disk drive.
Replace the disk drive if the voltages are now within specifications (see
Chapter 5).
E. If the problem persists, replace the CPU/Motherboard (see Chapter 5) and
repeat this procedure.
F. After you verify that the power supply voltages are within the specified
ranges, power off the system and unplug the ac cord from the wall outlet.
Replace the system unit cover. Make sure that all of the internal connec
-
tions are secure.
5. If the dc output voltages are within tolerance, perform the following three
steps:
A. If the fan does not operate, replace the power supply.
B. If the display outlet ac voltage is incorrect, replace the power supply.
C. If the power LED is not on, replace the Power-On Switch Panel. If the
LED still doesn’t light, replace these FRUs in the following order:
Ribbon Cable (connects LED board to CPU board)
LED Board
CPU Board
You can check the LED board and CPU board before you replace them by
checking the power LED circuits for continuity as shown in Table 4-19.
Check for continuity with Connectors J004 and J002 unplugged. Refer to
Figure 4-18 for the locations of the connectors and pins listed in
Table 4-19.