I like this power supply, but it's got a huge design flaw. It has three voltage ranges which can be set independently for voltage and current limits in the range of 0-16V @ 5A, 0-27V @ 3A and 0-36V @ 2.2A. When you select a range it stores it in memory and lights an LED to show the range it's in. But occasionally it blips, and when it does it shows no range selected (all LEDs out) and presents the voltage set on the highest range unexpectedly. This is not good for low voltage circuitry. Note that the voltage it was putting out was the one set for the highest range.
The issue seems to affect the same unit under various brands, but this one came from Maplin Electronics in the UK. I do recall seeing an angry review on their website raising this issue which was deleted.
It's a shame as the unit is otherwise very good.
Note that the 39.86V displayed when pressing random buttons was the upper voltage limit, and perfectly normal.
At a wild guess this may be a software issue involving corruption of the file that is used for the two bit setting (four possible values) of the voltage range. When it erroneously selects the one value that doesn't relate to one of the three ranges. That's hinted at by the missing range LED and default output of the voltage selected in the highest range. That suggests a possible safeguard might be to make sure that the other voltage settings are programmed to a safe low level like 3V when not in use.
The most annoying thing about this quirk is that it only happens once in a blue moon. I decided to film it if it happened again, and here's the video of that rare occasion.

17 thoughts on “Why i never show my power supply.”
  1. Avataaar/Circle Created with python_avatars LNG LNG says:

    ❤🎉

  2. Avataaar/Circle Created with python_avatars Little Clem says:

    If only you knew someone who could fix electronic equipment. Hmm Who could we get…..?………………….LOL

  3. Avataaar/Circle Created with python_avatars MiniLab says:

    I had precisely the same PSU many years ago, also obtained from Maplin. Got rid of it fairly quickly 🙂

  4. Avataaar/Circle Created with python_avatars Alex Attis says:

    Do you still use this power supply today, or have you gotten something else? I also wonder if they were able to fix that problem that it has.

  5. Avataaar/Circle Created with python_avatars Richard Parker says:

    Lol, no worries about anyone buying one of these from Maplins any more!

  6. Avataaar/Circle Created with python_avatars JustAlex says:

    I miss Maplin, it was one of the only good electronics shop

  7. Avataaar/Circle Created with python_avatars Htiek Mahned says:

    That's a very special embedded feature to signify that it's well overdue for another Ozone Generator teardown video!! 💜

  8. Avataaar/Circle Created with python_avatars Classical Rips says:

    Why does this video have no audio?

  9. Avataaar/Circle Created with python_avatars Mick Wilson says:

    Be great if you did “build a bench PSU” vid, I’ve seen a couple Yoo Toobers make one out of an old AT style computer PSU, but there seems to be way too many compromises.

  10. Avataaar/Circle Created with python_avatars Andrew Young says:

    Very late to the party but I also have one of these, the exact model one which was also from Maplin well over 10 years ago. I can't say I've ever had this issue, so I have to wonder if your unit is faulty? (Or if there are different versions of the software)

    It's a great little power supply, but my biggest issue with it is how slow the voltage / current adjustment is. It takes many turns as the encoders are not "velocity sensitive". Sadly Maplin no-longer sell them.

    Extech seem to have a newer auto-ranging version, the DCP36.

  11. Avataaar/Circle Created with python_avatars Bob Sage says:

    Ouch! 😲
    And that, boys and girls, is why the crowbar circuit was invented…

  12. Avataaar/Circle Created with python_avatars Alex Mac says:

    Let's discuss Power Supplies. . . . . . more

  13. Avataaar/Circle Created with python_avatars stian nobelisto says:

    "Maybe it needs some rest" …as many non technical people will tell you…

  14. Avataaar/Circle Created with python_avatars Neville says:

    then it's not a power supply….it's randomized circuit vaporizer…….i want one of those.

  15. Avataaar/Circle Created with python_avatars Blowing Channel says:

    ㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤ

  16. Avataaar/Circle Created with python_avatars Alan Deane says:

    I have the same PSU, also from Maplins. AFAIK, mine has never crashed…

  17. Avataaar/Circle Created with python_avatars pev says:

    So I have to ask: Why the fuck would you use an ebay (or similar) power supply??! You are an electronics expert, I would think that as such you would VERY MUCH want to have the basics, like a power supply and multimeter and oscilloscope, to be the most reliable and invest some money on them!! If you just want to make videos about how awful your equipment is, go ahead and use the most awful equipment, but you are a technical person and your videos are mostly about how awful some ebay devices are, so the equipment you use to test them should NOT be suspicious!

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