PWM Alarm on Screen: How to Troubleshoot and Fix It
Step-by-step guide to diagnosing and resolving the PWM alarm on Thunder Laser machines by checking fan board and TL Timer connections.
Applies to: All Thunder Laser machines | You'll need: Access to the back of the machine (fan board) and left-side door (TL Timer)
The PWM (Pulse Width Modulation) signal is sent from the controller (DSP) to the fan board, which then tells the laser tube how much power to output. It is a 0–5 V signal corresponding to the min and max power range of the tube (approximately 1–99%).
Fan board
Located at the back of the machine, near the laser tube. It is a small green printed circuit board with white connectors and wires. It will have many red indicator LEDs — red is normal and does not indicate a problem.
On the fan board layout: the red-boxed connectors are the K-ON and K-OK/L-ON connectors; the red arrow points to the PWM signal input from the DSP. Indicator LEDs above the connectors show their status.
TL Timer board
Located on the left-hand side of the machine, behind the door. It is a large green printed circuit board with white connectors and wires. It will also have many red indicator LEDs — red is normal and does not indicate a problem.
The K-OK, K-ON, and L-ON wires from the fan board connect to the TL Timer board (highlighted in the red square) at the top right and bottom of the board.
| K-OK (In-11) | K-ON and L-ON |
|---|---|
 |
 |
Power up the machine and bypass the doors so you can observe the fan control board while the machine is live.
To bypass the doors, locate the Door board integrated into the TL Timer and press the button shown:
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Check the K-OK/L-ON and K-ON connectors on the fan board. Confirm they are fully and securely connected.
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Check the K-OK/IN-11 connector on the TL Timer board. Confirm it is fully and securely connected.
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Check the two shutter ports on the TL Timer board. Confirm both are fully and securely connected.
If all three steps check out, the LEDs on the fan control board should light up as shown below:
Once finished, undo the door bypass by pressing the Door Bypass Button again:
Option 1: Disable the shutter in Factory Settings
- Log in to the Factory Settings option under your Menu using the password CC8888.
- Scroll down to the Shutter option and select Closed.
Option 2: Power-up with door open (Class II machines only)
- Before powering up your machine, open the left-hand side door.
- Power up the machine and allow it to complete the homing routine.
- Close the door.
Still stuck?
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