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🛠 Repair of the Day! Samsung S21FE (G990F) – Charging Very Slowly (drawing only 0.4A) and Warning on Screen ⚠️
This situation occurs when the charging device is connected:
First, we check the flex cable connectors on the bottom board and the interconnect flex cable.
We connect the bottom board for testing. The problem remains the same.
We remove the main board and trace where the charging detection contacts go. We test the D+ and D- contacts on the system port with a tester and find almost zero resistance on one of them.
We take a donor board with screens already removed and use the tester in continuity mode to determine where these contacts go. 😊
It turns out that the D+ and D- contacts pass through a dual inductor and diodes.
We observe that one of the diodes is burnt, causing a short circuit on this line!
We desolder the damaged diode and check the line with a multimeter. The resistance is now the same as the neighboring line.
We reinstall the board back into the housing and test the charging again. Now it charges properly in both fast and super-fast charging modes.
Then we proceed with the complete reassembly and gluing of the device. 😊
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