Raspberry Pi PWR LED illuminates, but doesn't turn on or faint buzzing when connected to power Repair

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Raspberry Pi PWR LED illuminates, but doesn't turn on or faint buzzing when connected to power Repair
Device	Raspberry Pi
Affects part(s)
Needs equipment
Difficulty
Type

Problem description

PWR LED illuminates but doesn't turn on or faint buzzing when connected to power supply. Missing voltages at a GPIO pin.

• Pi 3 (A+ and B+)
• Pi 4 (all)

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Symptoms

• The red PWR LED illuminates, but the system doesn't turn on.
• There is a faint buzzing sound when power is supplied to the PCB.
• 5V present at GPIO 2, but no 3.3V on GPIO 1.

Solution

See Raspberry Pi MXL7704