Intermittent Power-On, Shutdown, Reboot - HP ZBook 14U G5 Maintenance And Service Manual

Items
Tips and tricks

Intermittent power-on, shutdown, reboot

Items
Symptoms
● Does not always turn on
● Intermittently hangs
● Intermittently shuts down
Spontaneously reboots
●
The sections below are intended for authorized service providers/technicians.
Procedures
At this point, there should be sufficient power from the AC adapter to the system
board. Expect to hear the fan spinning and see blinking lights or error messages (i.e.,
faulty memory, HDD, etc)
Verify Power Good (Troubleshooting) lights
1. Verify if the system board has power-on issue related. If there is no power-on
issue, move to next steps. For more information, see
(Troubleshooting) lights on page
2. Verify all connections and reseat parts
on page 98).
Verify system board
1. Test essential hardware configuration
on page 99, 12. Test with verified working configuration (hardware and/or
operating system) on page
removing nonessential parts.
2. If there is still no boot, replace system board.
Computer automatically boots without pressing power button when RTC 3V battery
has been removed. Therefore, after the service door and RTC 3V battery are removed,
no need to press power button from top side.
In essential hardware configuration, mWS G1 and G2 may require discrete GPU to boot.
However, mWS G3 can boot with integrated graphics.
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Procedures
Possible causes
Electrical short, fluctuating power source, unstable power rails, loose connections, bent pins,
stray wires, dust, obvious damage, nearly faulty parts (bulging/leaking capacitor).
Potentially will turn into a no power issue soon
Troubleshooting steps
1. Visually check power ports on both AC adapter and computer sides.
2. Inspect power sources:
a. Verify AC adapter working correctly. Use a confirmed working adapter to test.
b. Verify that battery is not depleted while system is in Sleep state. Test with a
confirmed working battery.
1. Follow actions in No Power on page
Power Good
96.
(10. Reseat cables and connections
(11. Test with minimum configuration
100, 13. Replace the system board on page
(No Power on page 103).
103.
Common issues and possible solutions 105
100) by