If you want to use the air assist through the mainboard,

1. Access "Vendor param" on RDWorks. (password: rd8888)
2. Click "Other".
3. Tick the box before "Enable blower".
4. Access user parameters.
5. Click "Other" to see the dropdown list.
6. Set "Blow type" to "Lase on blow".
7. Measure the voltage between the 24V port and the "wind" or ("Aux-air") port of the mainboard. This reading varies when the engraver starts and stops working; if you keep getting the same reading whether the engraving is working or not, then the mainboard is faulty. Replace with a new, identical one.

If the voltage does change as the engraver work,

• Connect the 24V port with the "wind" or ("Aux-air") port using a 24V relay.
• Wire the exhaust fan to the relay so that the relay can turn it on and off.