What Was Happening
The laptop had stopped powering on. The customer’s first reaction was that the laptop itself was broken, and they brought it in expecting expensive internal repair. They also asked us to check whether the integrated camera was still working — they’d had occasional issues with it and wanted to confirm before deciding whether to keep the laptop or replace it.
Both questions had good answers, neither of them what the customer was expecting.
Our Diagnosis
For “won’t power on”, the diagnostic order is unambiguous: prove the laptop works before assuming it doesn’t.
- External examination of the charger. Looked for visible damage to the brick, the cable, and the connector. The cable had a slight kink near the brick — a common failure point. Not conclusive on its own, but worth noting.
- Charger output test, externally. Multimeter on the output of the charger, no laptop connected. Read showed the correct voltage at no-load. So far so good — but a charger can read correctly at no-load and still fail under any real current draw.
- Charger output test, under load. Bench-tested the charger under load to draw a representative current from the charger while measuring voltage. The voltage collapsed dramatically once the load exceeded a small fraction of the charger’s rated capacity. Conclusive — the charger was failing internally and could deliver low-power signals but not real power.
- Laptop on bench supply. Disconnected the customer’s charger and connected the laptop to a known-good bench supply at the correct voltage. Laptop powered on immediately, booted to login screen, ran normally. Laptop confirmed healthy.
- Camera test, while we had the laptop running. Opened the Windows Camera app — camera live, video working, microphone capturing sound. Camera question answered: healthy.
Outcome: the laptop was fine. The customer didn’t need an internal repair, just a new charger.
How We Fixed It
Specified a replacement charger matched to the original on:
- Voltage — HP laptop chargers come in several voltages depending on model and generation. Wrong voltage at best does nothing, at worst damages the laptop.
- Wattage — must be at least the original’s wattage. Higher is fine (the laptop only draws what it needs); lower will throttle or fail under heavy load.
- Connector type — barrel jacks, USB-C, HP’s proprietary “smart pin” connectors — all distinct, none interchangeable.
- Polarity — for barrel jack chargers especially, polarity matters and reversed polarity can damage the laptop.
Fitted the replacement charger. Powered the laptop from it, confirmed normal charging behaviour: light on at the jack, battery indicator showing “plugged in, charging”, current draw reasonable. Let the laptop run on the new charger for an hour to confirm no thermal or stability issues.
Briefed the customer on what went wrong and what to do with the failed charger (recycle it; don’t keep it in case it “comes back” — failed power electronics don’t recover and a partially-working charger can damage what’s plugged into it).
The Result
Laptop powering on normally and running on the replacement charger. Camera confirmed working. Customer saved the cost of an unnecessary internal repair quote and walked out with a laptop ready to use.
Why This Happens
A surprising proportion of “dead laptop” jobs we see are dead chargers rather than dead laptops. Charger failure is one of the most common laptop-related problems because:
- Chargers live a hard life. They get coiled around in bags, stepped on, yanked by the cable, dropped on the floor. Cables break at the strain reliefs by the brick or by the connector.
- Cheap replacement chargers are widespread. A bargain “compatible” charger may be specified loosely enough to work some of the time but not under real load.
- Power electronics fail silently. A charger can read the right voltage at no-load and completely fail under load. Without a proper load test, the fault isn’t visible.
- Customers correctly identify the symptom as “won’t power on” but incorrectly attribute it to the laptop. The visible thing is the laptop; the invisible thing is the charger doing its job.
The cost difference is significant. A replacement charger is a fraction of the cost of an internal repair. Diagnosing properly saves the customer money on the cases where this is the actual fault — and gets them back to a working laptop within hours rather than days.
How to extend charger life
- Don’t yank the cable to unplug. Pull on the plug, not the cable. The strain relief by the connector fails first when cables are pulled.
- Don’t coil the cable tightly around the brick when storing. Loose coils stress the cable less than tight ones.
- Avoid putting weight on the cable — chair legs, desk corners, the laptop itself sat on top of the cable.
- Replace the charger when it shows intermittent behaviour. A charger that “works sometimes” is a charger that will fail soon and may take other things with it.
- Carry a spare charger if the laptop is your work tool. A failed charger in the middle of a workday is more disruptive than the cost of a spare suggests.
When to suspect the charger vs the laptop
- Charger LED on but laptop dead — could be either. Bench test the charger under load.
- No LED on the charger — almost certainly the charger.
- Laptop powers on with battery but dies when charger is plugged in — failing charger pushing wrong voltage or out-of-spec ripple.
- Laptop runs on battery, charger plugged in but “not charging” — could be charger, could be DC jack, could be battery controller. Needs proper diagnosis.
- Laptop completely unresponsive, both with charger and (where removable) without battery — more likely internal, but still worth ruling out a bad charger first.
Local Help in Sheen SW14
Most laptop faults have a clear single cause once you separate the symptom from the underlying component.
We diagnose before we quote, so you’ll know what you’re paying for before any work goes ahead.
Visit our Putney workshop (SW15), call 020 7610 0500, or message us through the contact page.