Repair Workshop: laptop adapter not working

Read the safety step first, then pick the symptom. At every step we show what to measure, where and how; enter your reading and move on based on the result.

Step 1free trial: 3 steps left

Safety first: there's up to 400 V inside this adapter.

🔧 How to measure

With the box open, do live measurements through an isolation transformer and with one hand. Even after unplugging, the bulk capacitor can hold 300–390 V for minutes: discharge it and measure every time. Don't let the cutting tool touch the board when opening the case. Always do the first power-up after replacing parts through a series bulb. If you can't follow these rules, don't open the adapter; the cable and plug checks can be done from outside.

⚠ Mains voltage present: power the board through an isolation transformer, measure one-handed, and don't touch parts before discharging the bulk capacitor.

On a healthy board, at this point:

Multimeter≈390 V DC

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