Examine The Environment - HP EliteBook 850 G4 Maintenance And Service Manual

Failure classification by hardware devices and mechanical
Table 8-4 Failure classification by hardware devices and mechanical
4. Display
1. Display anomalies
on page 119
2. Dead pixel on page 121
3. No video (internal)
on page 121
4. No video (external)
on page 122
5. DisplayPort/VGA
on page 122
6. HDMI on page 122
7. No or bad external video
via docking on page 123
8. Incorrect or missing color/
distorted image
on page 123
9. Touch screen
on page 124
b,c,d similar symptoms

2. Examine the environment

It is important to examine the computer's environment. If you can quickly identify the cause of the issue,
fewer resolution steps may be needed. Perform the following environment inspections:
Check all cables and connections to be sure that there are no loose connections.
●
● Confirm that power sources are good, such as wall power type/adapter (110V/220V ac), power strip. Test
with a verified working AC outlet.
● Check for compatibility issues between the computer and third-party devices, peripherals, noncertified
devices, incompatible hardware (i.e., Mac OS device). Incompatibility can result in blue screen errors,
improper operation, and so on.
● Isolate the computer from sources of electromagnetic interference (EMI), such as cell phones, 2-way
radios, floor mats, fans (and other electronic motors). EMI may contribute to a display freeze issue or
lock-up.
86 Chapter 8 Troubleshooting guide
5. I/O devices
1. Keyboard on page 125
2. Keyboard point stick
on page 126
3. Keyboard backlight
on page 126
d
4. TouchPad on page 127
d
5. Network Connectivity
Ethernet (RJ-45 jack)
on page 127
6. Network connectivity
wireless (WLAN)
on page 128
7. WWAN on page 129
8. USB on page 130
9. Smart card reader
on page 131
10. Speaker, headphone -
audio issues on page 132
11. Thunderbolt (TB)
on page 133
6. Storage
1. Hard drive/solid-state
drive not recognized
on page 135
2. No boot to operating
system (no read/write
error) on page 135
3. Read-write error
on page 136
4. Slow performance
on page 117 c
5. Blue screen (BSOD) error
b
on page 136
6. Noisy hard drive
on page 137
7. Mechanical
1. Fan error message - 90B
on page 138
2. Noise (sound)
on page 139
3. Fan runs constantly
on page 140
4. HP Thermal Monitor
on page 91
5. Stuck power button
on page 141