You can watch on YouTube also in this video number {1002} SMPS output voltage fluctuating, unregulated output, i demonstrated how to test troubleshoot and repair 12 volt 5 ampere 60 watt, KA3842, KA2842, KA1842, UC1842, UC2842, UC3842 UCC1842, UCC2842 or UCC3842 based flyback converter switch mode power supply, its output voltage were unregulated and fluctuating. i explained the possible reasons related to this fault condition. br SMPS OutPut Voltage Low and Fluctuating, SMPS Output Fluctuation. How To Repair Switch Mode Power Supply when the output voltage are less than the rated voltage and it is giving unregulated voltage, after replacing the faulty potentiometer in feedback network, the power supply started working normally.