Laptops, mobile devices and printers

Desktops sit on desks; most of the computing at Ridgeline happens elsewhere. Kai carries ROAST-LT between the roaster and the office, Mei's baristas tap orders on tablets, Rosa runs the business from her phone, and the cafe and office depend on three very different printers. Each of these devices raises its own support questions: which parts can be replaced, how batteries age, how phones and tablets are kept secure, and why printers seem to cause more tickets than everything else put together. This lesson covers them in turn.

Laptops

A laptop contains the same parts as a desktop, rearranged to save space and power. The processor and graphics are usually soldered to the motherboard, and so, increasingly, is the memory. The storage is normally an M.2 NVMe drive that can be replaced. The keyboard, touchpad, screen, speakers, webcam, microphone and wireless card are all built in. Before opening a laptop, a technician checks the maker's service manual, because the order of disassembly and the hidden screws differ from model to model, and some parts, such as batteries glued into the case, are not meant to be replaced by users at all.

Laptops now charge mostly through USB-C, using USB Power Delivery, a standard in which the charger and the laptop agree on a voltage, up to 20 volts on most chargers and up to 48 volts under the newer extended power range, and therefore a power level. Kai's laptop came with a 65 watt charger. A smaller phone charger will still charge it, slowly, or only keep it from draining while it is in use; a larger charger is perfectly safe, because the laptop only draws what it needs. A docking station on the office desk connects ROAST-LT to a monitor, keyboard, mouse, wired network and power through a single USB-C or Thunderbolt cable, which is why Kai can arrive from the roaster and be working at a full desk setup in seconds.

Laptop batteries are lithium-ion, and they age. Every full charge and discharge cycle wears them slightly, and heat speeds the wear. After a few hundred cycles a battery holds noticeably less charge than when new, and after several years it may last only an hour. Windows can produce a battery report showing the design capacity and the current full-charge capacity, which tells you how worn the battery is. Laptops that live on a dock, as Kai's does in the office, benefit from a firmware setting that stops charging at about 80 in 100 of full, which greatly slows ageing. A battery that swells, pushing up the keyboard or the touchpad, is a fire risk: the laptop must be shut down, not charged, and the battery replaced and recycled properly, never punctured or thrown in the garbage.

# Estimating battery runtime from a battery report
design_wh = 54.0        # capacity when new, in watt-hours
full_charge_wh = 41.6   # capacity now
average_draw_w = 9.5    # typical power draw during Kai's work

health = full_charge_wh / design_wh
runtime_h = full_charge_wh / average_draw_w
print(f"Battery health: {health * 100:.0f} in 100 of design capacity")
print(f"Expected runtime: {runtime_h:.1f} hours")
if health < 0.8:
    print("Below 80 in 100 of design capacity: plan a replacement")

Battery health: 77 in 100 of design capacity
Expected runtime: 4.4 hours
Below 80 in 100 of design capacity: plan a replacement

def runtime_hours(full_charge_wh, draw_w):
    return 0

def needs_replacing(design_wh, full_charge_wh):
    return False

print(runtime_hours(41.6, 9.5), needs_replacing(54.0, 41.6))

Phones and tablets

Mobile devices are complete computers running mobile operating systems: Apple's iOS and iPadOS, or Google's Android in its many manufacturer versions. Their parts are almost never user-serviceable; support is about configuration, connectivity, accounts and security. Ridgeline's two point-of-sale tablets are a good example of what that involves.

Each tablet is enrolled in mobile device management, MDM, a service that lets Sam configure and secure devices remotely. Through MDM, the tablets are locked to the point-of-sale app in a kiosk mode, so customers cannot wander into other apps; updates are applied overnight; the staff Wi-Fi settings are pushed automatically; and a lost or stolen tablet can be locked or wiped from anywhere. Rosa's own phone, which she uses for company email, is handled differently: rather than managing the whole phone, the MDM service manages only a work profile that keeps company email and files separate from her personal apps and photos. That arrangement, common where staff use their own devices, respects privacy while protecting business data.

Mobile devices connect to accessories over Bluetooth, a short-range wireless standard. Pairing creates a trusted link between two devices, sometimes confirmed with a PIN or a matching code; after that, the devices reconnect automatically. Most Bluetooth tickets come down to a device paired to the wrong tablet, a flat battery in the accessory, or too many old pairings cluttering the list. The card readers at Ridgeline's counter each pair with one tablet, and the first fix for a reader that will not connect is to remove the pairing on both sides and pair again. Near-field communication, NFC, works over a few centimetres and is what makes tap-to-pay cards and phones work with the card reader.

Phones and tablets also synchronize data with cloud accounts: an Apple or Google account for contacts, photos and backups, and a Microsoft 365 or Google Workspace account for business email, calendars and files. When a user says their new phone has no email, the usual cause is that the business account was never added, or the account requires multi-factor authentication that has not been set up on the new device.

Printers

Printers generate a remarkable share of support tickets, because they combine moving mechanical parts, consumables that run out, drivers that must match the operating system and network connections that can change. Ridgeline uses three different printing technologies, and knowing how each works explains most of their faults.

The laser printing process is a favourite exam topic and also explains real faults. It runs in seven steps: processing the page into an image; charging the drum with a uniform electrical charge; exposing the drum with the laser, which removes the charge where the image will be; developing, where toner sticks to the exposed areas; transferring the toner from the drum to the paper; fusing the toner to the paper with a hot roller and pressure; and cleaning the drum of leftover toner and charge. A repeated mark at regular intervals down the page usually comes from a damaged drum or roller, and the distance between the marks often identifies which one. Toner that rubs off a printed page means the fuser is not getting hot enough.

ORDER = ["processing", "charging", "exposing", "developing", "transferring", "fusing", "cleaning"]
scrambled = ["fusing", "charging", "cleaning", "processing", "transferring", "exposing", "developing"]

def in_order(steps):
    return steps

print(" -> ".join(in_order(scrambled)))

Printers connect by USB, by the network, either wired or Wi-Fi, or through cloud print services. Network printers are best given a fixed address, set either on the printer or reserved for it on the router, so that computers can always find them; a printer whose address changes after a power cut is a classic cause of a sudden can't-print ticket. Each operating system needs a driver for the printer, although many modern printers support driverless standards such as the Internet Printing Protocol with AirPrint or Mopria, which let phones and tablets print without installing anything. On Windows, the print spooler service queues jobs; a stuck job at the front of the queue blocks everything behind it, and clearing the queue or restarting the spooler is one of the most common printer fixes of all.

Thermal printers need care in a different way. Receipt and label paper must be the right width and loaded with the heat-sensitive side facing the print head; a roll loaded backwards prints blank receipts, which is the first thing to check when CAFE-PRN1 produces paper with nothing on it. Theo's label printer must be told the label size, four by six inches for most shipping labels, or it prints across the gaps between labels. Thermal print heads collect dust and adhesive and should be cleaned occasionally with an isopropyl alcohol pen.