Grounding guidelines, Event 10% 40% 55%

Grounding guidelines

Electrostatic discharge damage

Electronic components are sensitive to electrostatic discharge (ESD). Circuitry design and structure determine the degree of sensitivity. Networks built into many integrated circuits provide some protection, but in many cases, ESD contains enough power to alter device parameters or melt silicon junctions.

A discharge of static electricity from a finger or other conductor can destroy static-sensitive devices or microcircuitry. Even if the spark is neither felt nor heard, damage may have occurred.

An electronic device exposed to ESD may not be affected at all and can work perfectly throughout a normal cycle. Or the device may function normally for a while, then degrade in the internal layers, reducing its life expectancy.

CAUTION: To prevent damage to the computer when you are removing or installing internal components, observe these precautions:

Keep components in their electrostatic-safe containers until you are ready to install them.

Use nonmagnetic tools.

Before touching an electronic component, discharge static electricity by using the guidelines described in this section.

Avoid touching pins, leads, and circuitry. Handle electronic components as little as possible.

If you remove a component, place it in an electrostatic-safe container.

The following table shows how humidity affects the electrostatic voltage levels generated by different activities.

CAUTION: A product can be degraded by as little as 700 V.

Typical electrostatic voltage levels

		Relative humidity

Event	10%	40%	55%

Walking across carpet	35,000 V	15,000 V	7,500 V

Walking across vinyl floor	12,000 V	5,000 V	3,000 V

Motions of bench worker	6,000 V	800 V	400 V

Removing DIPS from plastic tube	2,000 V	700 V	400 V

Removing DIPS from vinyl tray	11,500 V	4,000 V	2,000 V

Removing DIPS from Styrofoam	14,500 V	5,000 V	3,500 V

Removing bubble pack from PCB	26,500 V	20,000 V	7,000 V

Packing PCBs in foam-lined box	21,000 V	11,000 V	5,000 V

Preliminary replacement requirements 35

CQ40-105TU, CQ40-109AX, CQ40-111AU, CQ40-114AU, CQ40-300 specifications

The HP CQ40 series laptops, including models like CQ40-120AU, CQ40-120AX, CQ40-131TU, CQ40-129AU, and CQ40-134TU, represent a blend of performance and versatility tailored for everyday computing needs. These laptops, which were released in the mid-2000s, are characterized by their solid build quality, a user-friendly experience, and a range of features that cater to both students and professionals.

One of the standout features of the CQ40 series is its display. Most models in this lineup boast a 14.1-inch diagonal widescreen display with a standard resolution of 1280x800 pixels. This display size strikes a balance between mobility and usability, making it easy to transport while still providing ample screen real estate for work and entertainment.

Performance-wise, the CQ40 series is equipped with a variety of Intel and AMD processors, depending on the specific model. The processors offer a mix of efficiency and performance, making them suitable for everyday tasks such as web browsing, document editing, and media playback. With RAM options typically ranging from 2GB to 4GB, users can expect smooth multi-tasking capabilities.

Storage options in the CQ40 series include hard drives with capacities that generally range from 250GB to 320GB. This storage provides adequate space for files, applications, and media, ensuring users can keep their important documents within easy reach.

In terms of connectivity, the CQ40 laptops are equipped with multiple USB ports, HDMI outputs, and audio jacks, allowing for easy peripheral connections ranging from external drives to printers. They also typically feature Wi-Fi and Ethernet capabilities, ensuring users stay connected whether at home, in the office, or on the go.

Battery life is another consideration, with most models designed to last several hours on a single charge, depending on usage patterns. This aspect makes the CQ40 series a reliable option for users who need to work remotely or during travel without being tethered to a power outlet.

Overall, the HP CQ40 series, including the models CQ40-120AU, CQ40-120AX, CQ40-131TU, CQ40-129AU, and CQ40-134TU, remains a practical choice for budget-conscious users seeking a dependable laptop for day-to-day tasks. With a combination of decent performance, good battery life, and essential features, these laptops continue to serve a purpose in the computing landscape.