Charging and data schematic for the Samsung SM-A21s, PDF, 3.82 MB. It covers the USB connector, protection components, charging circuitry and USB data lines. This is the page to use for no-charge, slow-charge or no-PC-connection faults: measure VBUS, check protection parts for a short, and trace the data lines toward the processor side. Opens in any PDF viewer. Confirm the board is from an SM-A21s before trusting designators, as similar Samsung models are wired differently.
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