Intermittent Power-On, Shutdown, Reboot - HP ZBook 15 G4 Maintenance And Service Manual

Tips and tricks

Intermittent power-on, shutdown, reboot

Symptoms
● Does not always turn on
● Intermittently hangs
● Intermittently shuts down
Spontaneously reboots
●
The sections below are intended for authorized service providers/technicians.
1. Test essential hardware configuration
on page 91, 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.
See "Overview of How to Troubleshoot Problems When a Computer Does Not Start Up
or Boot Properly" at http://h20566.www2.hp.com/hpsc/doc/public/display?
docLocale=en_US&docId=emr_na-c01443371
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. Make sure drivers are updated.
2. Visually check power ports on both AC adapter and computer sides.
3. 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
a. Be sure that AC adapter has correct DC voltage.
b. Verify battery - test with a confirmed working battery.
c. Verify that power button is not stuck.
d. Verify that power connector is not loose.
e. Verify that Power Good LEDs are solid.
f. Remedy loose connections and reseat major components (processor,
memory, GPU, hard drive/solid-state drive, etc).
2. Perform visual check for loose connections, bent pins, stray wires, dust, nearly
faulty parts (bulging/leaking capacitor).
(11. Test with minimum configuration
92, 13. Replace the system board on page
(No Power on page
95.
Common issues and possible solutions
92) by
95).
97