samsung A40 charging ways & jumper solution

Charging failure is one of the most common issues faced by Samsung smartphones, especially devices using the USB Type-C port like the Samsung Galaxy A40 (SM-A405).

samsung A40 |SM-A405| charging ways jumper problem

Many users initially assume the problem is caused by the charger or the battery, but in reality, the fault is often hidden inside the phone’s charging pathways, flex cable, or the mainboard’s charging IC circuits.

🔧 Samsung Galaxy A40 (SM-A405) Charging Ways & Jumper Solution – Complete Repair Guide

In this detailed repair guide, we will walk through all diagnostic steps, explain how the charging line works in the Galaxy A40, and demonstrate the charging jumper solution used when power tracks are broken or damaged.

📌 Overview – Why the Galaxy A40 Stops Charging

The Galaxy A40 charging system depends on three main hardware components:

1. Charging USB-C port (located on the sub-board)
2. Sub-board (daughterboard) with charging filters and basic circuitry
3. Main motherboard, where final charging regulation is handled by the Charging IC and Power IC

A fault in any part of this chain can result in:

• Phone not charging
• Slow charging or “charging paused”
• Charging only when applying pressure

No response when the cable is connected

🛠️ Step-by-Step Diagnostics for Samsung A40 Charging Problems

To accurately identify the issue, technicians should follow a structured testing sequence:

🔍 1. Test the USB-C Charging Port

Start with a physical and electrical inspection:

• Check for dust, corrosion, or liquid damage
• Verify that the port pins are not bent or loose
• Use a known-good cable and charger to confirm power input

If the port is physically damaged, replace the sub-board.

🔍 2. Check the Charging Sub-Board (Bottom Board)

The SM-A405 sub-board contains:

• USB-C port
• Mic
• Charging filters
• First-stage charging tracks

Using a multimeter:

• Test VBUS (5V input)
• Check the continuity of charging lines
• Verify that no components are shorted or burnt

If the sub-board is working correctly, move to step 3.

🔍 3. Test the Interconnect Flex Cable

The flex cable that connects the sub-board to the mainboard frequently causes charging problems when:

• A line inside the flex is broken
• The connector becomes loose
• Moisture affects the internal wiring

A faulty flex cable leads to:

• Intermittent charging
• No charging
• Sudden disconnection

Replace the flex if continuity fails.

🔍 4. Inspect Charging IC and Power Tracks on the Mainboard

If all previous parts are good, then the issue is in the charging pathways on the motherboard. These include:

• Charging IC circuits
• Power IC input line
• Broken or burnt charging tracks

When a track is damaged, the phone will not receive the required voltage, even if the sub-board works perfectly.

SAMSUNG A40 CHARGING WAYS | A405 CHARGING

This is where the jumper solution becomes essential.

🔌 Samsung A40 Charging Ways (SM-A405) – Jumper Solution

When testing reveals a cut or missing charging line between the sub-board and the motherboard: