Smartphones have become an essential component of our daily lives, and it can be frustrating when one malfunctions. In this blog post, we’ll delve into a real-world repair case involving a Samsung Galaxy S10+ that refused to power on. The journey to bring this device back to life uncovers a series of intricate diagnostics and skilled repair work.
Understanding the Problem: Assessing the Motherboard
- The first step in troubleshooting this non-responsive Samsung Galaxy S10+ was to examine the motherboard.
- It was discovered that both the power IC and camera IC had previously been soldered, making it crucial to consider these modifications.
Identifying the Issue
Upon inspection, we discovered an unusual power leakage of 52 mA from the motherboard, indicating a potential issue with the primary power supply line.
When attempting to power on the phone, there was no change in the current reading, suggesting a problem with the main power supply line.
Diode Mode Measurement
To pinpoint the issue, various power supply lines on the motherboard were measured using the diode mode of a multimeter.
In this process, a critical revelation was made: the inductor L5039 was shorted to the ground.
Schematic Analysis
Referencing the schematic diagram revealed that L5039 was not only connected to the main power supply line (VBAT) but was also linked to the power IC, U8031.
Since power IC U8031 has been soldered before, we need to find out if it is faulty in the first place. Attach the motherboard to the holder and apply some Paste Flux to the power IC.
Heat with Hot Air Gun at 340 °C and airflow 3 to remove the IC.
Clean the bonding pad with Solder Wick. Measure the inductor L5039 with diode mode of the multimeter. The diode value is 289, which is normal. We can judge that the power IC fault has resulted in the short-circuit of the main power supply line.
Clean the bonding pad with PCB Cleaner and apply some Paste Flux.
Align the new IC. Solder the new IC with Hot Air Gun at 340 °C and airflow 2. After the motherboard has cooled, connect the power cable.
Trigger the boot-up with tweezers. The boot current returns to normal.
Install the motherboard. The phone turns on normally. The fault has been cleared.
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Watch the below video to see how we fix the Samsung Galaxy S10 Plus that won’t turn on.
