Samsung Galaxy A53 5G Network issue

Samsung Galaxy A53 5G Network issue
Device	Galaxy A53 5G
Affects part(s)	Logic Board
Needs equipment	Soldering Iron, Hot Air Station, Microscope
Difficulty	◉◉◉◉ Specialist
Type	Soldering, BGA

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Problem description

In this condition, your phone experiences severe network issues. You may notice one or more of the following:

• No network service.
• Only emergency calls are possible.
• Complete inability to make or receive calls.

Symptoms

• The phone continuously switches between "Emergency Calls Only" and "No Service."
• Sometimes signal bars appear, but they are only for emergency calls.
• Occasionally, a blocked or crossed-out icon replaces the signal bars.
• Flight Mode can be toggled normally (the button is not greyed out or stuck).

• You can manually switch between different network modes (2G, 3G, 4G, 5G), but the problem remains.

Root Cause

The issue is usually caused by a malfunctioning or shorted APT IC located near the CPU. When the APT IC fails or operates inconsistently, it disrupts the network power supply (VPA_APT), leading to unstable or no network service.

Solution

There are 2 ways to fix this issue:

1. Replace the ic.
2. Bypass the ic but not by removing it

front network section

Diagnostic Steps

1. Check for Shorts:
   • Inspect the area around the network-related ICs for short circuits (see the image)
2. Measure VPA_APT Output:

VPA_APT COIL

• Probe the VPA_APT coil output (in the picture)
• The expected voltage should be in the range of 2.0V to 4.2V (depending on battery voltage)
• If the reading is 0.00V or fluctuates continuously, proceed to repair steps

Repair Steps

Solution 1: Replace the APT IC

VPA_APT IC

• Remove the shield covering the IC.
• Desolder and remove the faulty APT IC(shown in the picture)
• Inspect the PCB pads for any damage.
  • If pads are intact, proceed.
• Reball the replacement APT IC using 183°C (medium-temp solder paste).
• Install and solder the new IC onto the board.

• Verify the repair by checking network functionality.

Solution 2: Bypass the APT IC (Jumper Method)

VPA_APT to VPH_PWR JUMPER

• Locate the VPH_PWR point on the motherboard (shown in the picture)
• If the APT IC is burnt, first remove the VPA_APT boost coil.
• Create a jumper wire connecting VPH_PWR to the VPA_APT output (refer to image for exact points).
• Apply solder mask to secure the jumper and prevent shorts.

• Test the phone’s network functionality.