VOLUSON E8 BT18 POWER SUPPLY FAN FAILURE

Hello! VOLUSON E8 BT18 FAN FAILURE After a few hours of hard examination work, the scanner stops and the following message pops up on the main display. The power source reported about accident. PS Code (0x5461) - Data (0100) - FAN1 Defect ----- It happens daily. Only shutdown and reboot help. Has anyone of you met this? Any solution? I suppose that the scanner is overheated. There 3 FANs on the back power supply. Is this 1 of 3 Fans broken? Or a fan controller in the power supply? I will appreciate you advices.