Laser Welding Troubleshooting Guide：No Laser Output but Gas and Wire Feeding Working

In laser welding applications, one common issue users may encounter is that the machine operates partially but fails to emit laser light.

This article explains the typical symptoms, root causes, and step-by-step solutions to help you quickly diagnose and resolve the problem.

Problem Description

During welding operation:

Gas is released normally

Wire feeding works properly

Red light (pilot laser) is visible

But no laser beam is emitted

This means the system is partially functioning, but the actual laser output is missing.

Root Cause Analysis

Under normal conditions, when gas is triggered, the laser output signal should also be sent simultaneously.

If the laser does not emit, the issue is usually related to one of the following:

The laser source does not receive the output signal (possible port or signal issue)

The laser source itself has a fault

Signal transmission between the control system and laser source is abnormal

It is important to note that:

A laser source showing no alarm does not necessarily mean it is functioning properly.

Troubleshooting Steps

Step 1: Check Control Signal Output

In principle, when the control box sends the following three signals, the laser should be triggered:

Enable signal

PWM signal

Analog signal

If your system has a monitoring interface, check the signal values during operation.

If all output signals show normal values, it indicates that:

The control system is working properly

The issue is likely external, most probably the laser source

In this case, it is recommended to contact the laser source manufacturer.

Step 2: Manual Signal Testing (For Systems Without Monitoring Function)

If your system does not include a monitoring interface, you can manually test the signals.

You can do this by:

Running the machine in working mode (gas or wire feeding active), or

Using diagnostic mode to independently activate Enable, PWM, and Analog signals

Important:
Before measuring, disconnect the cable between the control box and the laser source (signal interface 3).

Step 3: Measure Signal Outputs

Use a multimeter to check the following signals:

Enable Signal
Pins 2 and 4 should output 24V

PWM Signal
Pins 6 and 7 should output 24V

Analog Signal
Pins 4 and 5 should output proportional voltage
At full power, the voltage should reach approximately 10V

Diagnosis Based on Test Results

Case 1: All Signals Normal, but No Laser Output

If all signals are correct and stable, but the laser still does not emit:

The issue is most likely with the laser source itself

Solution:
Contact the laser source supplier for inspection or repair

Case 2: Missing Enable or PWM Signal

If either Enable or PWM signal has no voltage output:

You can temporarily combine them for testing

For example:
Connect PWM signal to the Enable signal pin

This can help verify whether the issue is related to signal transmission

Case 3: No Analog Signal Output

If the analog signal has no voltage:

Further diagnosis depends on the red light condition

If the red light appears as a line:
The control board may be faulty

Solution:
Return to factory for repair or replace the mainboard

If the red light appears as a dot:
Check whether the 15V switching power supply polarity is reversed

Key Takeaways

No laser output does not always mean the laser source is damaged

Always verify control signals before replacing components

Signal testing is critical for accurate troubleshooting

Proper diagnosis can save significant repair time and cost

Need Technical Support

If you encounter similar issues with your laser welding system,

ZS Laser provides professional technical support and remote diagnostics to help you quickly restore production.

Feel free to contact our team with your machine details and fault description.