SMT Troubleshooting

Introduction

SMT production problems often appear as isolated issues, such as PCB transfer failure or random line blocking.
However, in most cases, these symptoms are connected to unstable PCB transfer and poor line coordination.

This troubleshooting hub focuses on the most common PCB transfer–related SMT issues and provides structured guidance to help engineers identify root causes and improvement paths.

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Section 1：What Causes PCB Transfer Issues in SMT Lines?

PCB transfer problems are rarely caused by a single machine.
They typically result from:

• Unstable SMEMA signal communication

• Conveyor timing and alignment mismatch

• Mixed-brand equipment integration

• Missing buffers between processes

• Inspection processes interrupting PCB flow

Understanding these factors is the first step toward stable production.

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Section 2：Common SMT Troubleshooting Scenarios

Below are the most frequently reported SMT issues related to PCB transfer and line stability.

🔹 PCB Not Transferring Between Reflow Oven and AOI

Typical Symptoms

• PCB stops at reflow oven exit

• Manual intervention required

• Random transfer success after reset

Root Focus

• SMEMA timing mismatch

• Conveyor alignment

• AOI input logic

👉 Read full analysis:
🔗 PCB Not Transferring Between Reflow Oven and AOI – Causes and Solutions
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🔹 SMEMA Signal Not Working Between Different SMT Machine Brands

Typical Symptoms

• PCB does not transfer automatically

• Conveyor stops without clear alarms

• Inconsistent behavior across machines

Root Focus

• Cross-brand SMEMA implementation differences

• Signal logic and grounding issues

👉 Read full analysis:
🔗 SMEMA Signal Not Working Between Different SMT Machine Brands

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🔹 SMT Line Blocking Caused by Unstable PCB Transfer

Typical Symptoms

• PCB accumulation at certain stations

• Frequent upstream machine stops

• Heavy operator involvement

Root Focus

• Lack of buffering

• Inspection flow interruption

• Unstable PCB transfer coordination

👉 Read full analysis:
🔗 SMT Line Blocking Caused by Unstable PCB Transfer – How to Fix It

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Section 3：Why These Problems Are Often Connected

Although these issues appear different, they often share the same root cause:

PCB transfer is not treated as a system-level process.

When SMT lines grow more complex, local parameter adjustments are no longer sufficient.
Signal logic, conveyor timing, buffering, and inspection routing must be coordinated together.

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Section 4：When Troubleshooting Requires a System-Level Solution

If you experience any of the following:

• Problems reappear after adjustments

• Issues increase after adding equipment

• Multiple transfer points show instability

• Operators frequently intervene

Then troubleshooting should move beyond individual machines.

👉 Please refer to our SMEMA & Automation Solutions for a structured approach to stable PCB transfer and SMT line coordination.