Faulty power supply? High output noise. (Matsusada PK-80H)

[TheAmmoniacal]

I bought a small high-voltage power supply some time ago (320 V DC, 500 mA, 80W) for use in electrophoresis (biology stuff), as I bought it used on eBay I did some simple health checks and cleaning. In measuring the output on the scope I noticed quite a bit of noise and ripple, is it faulty?

According to the specifications the ripple is max 20 mVrms and 1 mArms. I don't have a good unit to compare it against, and not sure how much ripple and noise I should expect from a small HV switching supply like this, anyone else know if this is normal?

This how I measured it:


This is what it looks like in CV mode (19 V), 499 mA. Audible whining noise.


This is CC mode (20 V), 500 mA (same scale as the one above)