Careful with the rebadges. I bought a Velleman unit (PS3005D, which is actually a Korad KA3005P (i.e., has the serial and USB ports. Korad's -D models don't have them)). While the hardware issues are no longer present (the boards are like the fixed revision that were shown in the videos), the firmware has a couple of issues, at least some of which seem to be fixed with the non-rebranded Korads (I might be wrong, it's just the impression I got watching videos):
- It has 5 storage positions (M1-M5), whereas the up to date Korads have 4. The 5th storage position is accessed by Pressing M4, then turning the wheel clockwise. The kicker is: it always switches to M5 if you turn the wheel, even if you wait after pressing M4, or the key panel is locked! At least the output is switched off whenever the storage position is changed.
- It has no LED for the lock.
- OVP doesn't work. The procedure described in the manual for setting the voltage limit does nothing.
- OCP kinda works: it's not a separate limit, instead it means that if you hit the set current limit, the output is switched off instead of the PSU going into CC mode. I'm getting the impression that there is no real limit though that would save you in case the PSU partially failed.
- Even if beeps are switched off, it still beeps whenever you press the OCP button. And the beeps are loud and sound horrible.
I've thought about modifying the firmware, but all writing on the chips has been filed off, and I can't be bothered to identify the chips. Maybe someone else can provide some info?
Btw, overall I'm still happy with the power supply. It has quirks, but it works, it's quite small and the fan is quiet while using low currents. The displayed voltage reads 0.02V high in the single-digit V range that I use most. If you've set a low current limit (< 1A), there is a bit of overshoot when switching on the output, probably because the supply goes into CC mode during ramp-up (the CC LED flashes briefly). If you set it at 1.5A, there is no overshoot. (I only tested it with small loads around 1W however.)
If you do get one, buy the newest revision (recognizable by the lower right LED being labelled "LOCK" instead of "M5".)