Measure the voltage between the IN and GND of the 6-pin terminal with the power set at different levels.

• If the voltage measures similar, the mainboard is faulty. Replace it with a new, identical one.
• If the voltage varies, see Ceramic Resistor Test>> to connect the ceramic resistor. Test whether the current of the laser power supply varies under different power settings. If the current does not change, replace the laser power supply with a new identical one. If the current changes, replace the laser tube with a new, identical one.