SMT Troubleshooting

SMEMA Signal Not Working Between Different SMT Machine Brands

Problem Description

SMEMA is a widely used standard for PCB transfer in SMT lines.
However, signal communication issues often occur when machines from different brands are connected.

Typical symptoms include:

• PCB does not move after transfer request

• Conveyor stops randomly

• Board transfers only after manual reset

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Why This Happens

Although SMEMA is a standard, machine implementation differs by manufacturer.

Common causes include:

• Different interpretation of SMEMA signal timing

• Incorrect cable wiring or pin assignment

• Missing ground reference

• Mismatch between active-high and active-low signals

• Incompatible default settings between machines

SMEMA problems are often logic-related, not hardware failures.

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Common Mistakes

Frequent incorrect actions include:

• Assuming SMEMA cables are plug-and-play

• Ignoring signal timing and handshake logic

• Adjusting only upstream or downstream machines

• Replacing hardware without signal testing

These approaches usually lead to repeated downtime.

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Practical Solutions

Effective SMEMA troubleshooting should include:

• Confirming SMEMA pin definitions on both machines

• Verifying signal states during board transfer

• Aligning signal timing and delay parameters

• Using buffers to absorb timing differences

• Standardizing PCB transfer logic across the line

A structured verification process is essential.

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When to Consider a System-Level Fix

If SMEMA issues appear during line expansion or equipment replacement, a line-wide automation review is recommended.

👉 Please refer to our SMEMA & Automation Solutions for professional support in resolving cross-brand SMEMA compatibility issues.

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This issue is part of a broader PCB transfer and line stability topic.
Please refer to our SMT Troubleshooting Hub.