YH11068A 10-32V ~ 45-390V dc/dc - overvoltage

It can be unnatural by turning the translator.

I bought this boost converter. Turn the variable resistor to set the desired voltage, then turn the power off and on. This will raise the voltage above the setting. What is the cause?

Boost converter model : yh11068(Single Output)
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I tried to build a simple low powered stereo amp (PCL82) with one of these for the HT supply. I tried 3 in total. The voltages where completely unstable. Current draw well within stated specs. The output would start to drop as soon as it was under load, very erratic. I'd love to know if anyone's used one successfully.