Testing Power Supply - HP Z400 Maintenance And Service Manual

Testing power supply

Before replacing the power supply, use the Built-In Self-Test (BIST) feature to learn if the power supply
still works.
To test the power supply:
1.
Disconnect the AC power.
2. Remove the internal power supply cables from the system board. (You do not need to remove the
power supply from the chassis.)
3.
If necessary, disconnect the PCIe power cable from the graphics card.
4.
Plug in AC power and verify the following:
If the green BIST LED on the rear of the workstation is illuminated and the fan is spinning, the
●
power supply is functional.
If the green BIST LED is not illuminated or the fan is not spinning, replace the power supply.
●
See the Rear panel components section of this service guide to locate the BIST LED on this workstation.
Table 6-2
Problem
Power supply shuts down
intermittently.
Workstation powers off and the
Power LED flashes red 2 times
(once every second), followed by a
2-second pause.
Power LED flashes red (once every
2 seconds).
176 Chapter 6 Diagnostics and troubleshooting
Power supply problems
Cause
Power supply fault.
Processor thermal protection is
activated.
A fan might be blocked or not
turning.
OR
The processor heatsink fan
assembly is not properly
attached to the processor.
Power failure (power supply is
overloaded).
Solution
Replace the power supply.
1. Ensure that the workstation air vents are not blocked.
2. Open the access panel and press the workstation
power button.
3.
Verify that the system fan is running.
4.
Verify that the processor heatsink fan spins.
If the heatsink fan is not spinning, verify that the fan
cable is plugged into the system board connector.
Verify that the fan is properly seated.
5.
Replace the processor heatsink.
1. Determine whether a device is causing the problem
by performing the following:
a.
Disconnect AC power.
b.
Remove all attached devices.
c.
If necessary, disconnect the PCIe power cable
from the graphics card.
d. Power on the workstation.
If the system enters the POST, perform the following:
a. Power off the workstation.
b.
Replace one device at a time and repeat this
procedure until a failure occurs.
ENWW