The power supply unit will automatically switch the laser off if the in-built over temperature protection system is activated. The laser can only be switched back on when the laser head has cooled down sufficiently. In case of overheating please check that adequate heat sinking is provided to the laser head. If a chiller is being used, please ensure that it is connected to the chiller plate on which the laser head is mounted and the fluid is circulating properly, this can be verified by opening the chiller and checking for movement of the water. If the PSU has fans, please ensure that nothing is blocking them and check that all the fans are rotating properly. If the cooling system and the fans are running properly and the laser head and /or the power supply unit are still overheating please contact our Support Team who will be happy to assist you.