• About EEVblog

    Check Also

    EEVblog #1047 – Solar Roadways FINALLY BUSTED! Colas Wattway

    Dave finally puts an end to the idea of Solar Roadways. We have the test ...

    • RyanE

      Says ‘This video is currently unavailable’.

    • bfritz

      It would be interesting to see if the terminals on the front of the unit can survive a 40A load. Are they just standard banana plug terminals, or multi way binding posts, that allow you to insert a wire, and clamp down on it? The HP/Agilent supplies I have seen at such high current loads, typically have a rear panel connection point for cases where you will actually use that much current.

    • Dan

      Can you see what it is yet:-)

    • Ted

      8400 has analog meters, 9400 is digital display. Found for $200 USD

    • Rasto

      This guy designed 13.8V 40A SMPS based around LM3524 for HAM radio , meaning low EMI radiation and good regulation is a must.

      Appears to be well done as well…


    • Nice teardown, thanks.

      Would anyone like to repair, for fee, or buy as faulty, an MP3090 that I had on my bench?

      The line fuse blew 3.5 years ago while charging a 12V SLA battery at about 14A, with the supply set at the fixed 13.8V. The battery had an inverter attached.

      The big electrolytics C10 and C11 were removed, tested, and found to be faulty. C10 and C11 were replaced with new components, but a corona near the power factor correction drive MOSFETs Q1 and Q2 suggest that the event damaged the PFC area too.

      Mail me on [email protected].

    • Bearman

      Good stuff Dave as usual. Thanx again.

      Speaking of ATX power supplies… has anyone ever tried to make a variable voltage supply out of an ATX PC power supply? Can you get schematics of one to see if it can be done?


    • huh

      Bearman, here are some info on PC PSU modifications. Hope it helps.


    • Rafael

      Nice teardown!

      The attention to detail, the protection circuitry and the quality of inductors and transformers throws PC power supplies to shame… Even some of the most expensive brands.

    • Anonymous

      That’s a whole load of money, though a whole load of amperes as well!

      If you were very positive about this PSU, you should take a look at Hitachi power supplies like the one shown in this forum post: http://afrotechmods.com/forums/index.php/topic,8943 . A bit of surplus goes a long way

    • Nice!

      The converter is a forward converter with a halfbridge at the primary side (the split primary caps already half the input voltage to the transformer, which is advantageous here…) and the standard center-tapped output configuration.


    • Brrr, CapXon…
      My experience with them:

    • Johan Olofsson

      I dont think the power supply was that well designed. Felt more like a system builder
      took a finished circuitboard and put in a box.

      From EMC point of view. just look at the still picture of the video (not started), they run the blue/black/red cables from the mains input right over the PFC and the mains filter on the circuit board, contaminating the supposed filtered cable. That could really explain why they have to have the separate shielded fiterbox at the input, and perhaps also the separate board with just a capacitor, and bleeder. It can also explain why they have to use flux-band on all their inductors/transformers. And the earth-wire running out of the shielded filterbox I don’t get. Its to long, gives high inductance considering a HF-filter.

      There is also another thing I really don’t get, if it is a high quality (Expensive) switched supply, why don’t they use a dual layer with a ground-plane? That would give better electrical/EMC performance and probably save some EMC-components not needed.. And they could use some SMD components. In the end I think it would be less expensive to use a dual layer PCB, if the TOTAL cost is considered.

      With this I don’t say bad power supply. I just see some improvements that could be made 🙂

      I would like to see some more teardown of power-electronics stuff 🙂

    • Th3_uN1Qu3

      I have to agree with one of the above posters: CapXon… nooooooo! 🙁

      Looks reasonably well-built, but the heatsinks could be bigger. I bet that fan is quite noisy.

      ATX PSUs can be modded, the difficulty ranges from “easy” to “better design it from scratch”, depending on what you’re trying to do. If you need under 20v, it’s quite trivial. Once you go higher, you’re gonna need to change the output inductor material from powdered iron to gapped ferrite. The -26 and -52 toroid cores typically found in ATX PSUs won’t cut it for over 20v at useful inductances and currents, they will saturate. Plus, winding toroids is a pain.

      Then there’s all the fun of changing the feedback loop to suit your new output filter, so the power supply doesn’t turn into a power oscillator. 😛

    • Pingback: Link Roundup: Power Supplies and Dummy Loads | Atom Hackery()

    • VK

      Hi I have 3x of these that I could do some help with please.
      First one the fan got noisy and eventually seized. At this point the device stopped working with an overload light on and reads 000 000 on the display. (No output).
      I freed up the fan (Full of dust) to test it but the overload light stays on and no output. (I will replace the fan once the device is fixed). Any idea’s?

      Second unit is going the same way. Fan is starting to make a grinding noise. (I will just replace the fan on this one). Is it considdered to be a 80mm fan? Would you suggest go to a ball bearing one for better life? etc

      Third is today dead. It was bought as a parts unit but could be resurrected. (I will look further into this one once the first two are corrected).

      None of thee supplies are loaded up excessively. They mainly run low end stuff like home network switches and routers etc.
      I use them because I want a nice clean 12VDC supply that is well filtered from RF etc.
      As at times I do run a Yaesu HF radio, VHF, & packet gear etc.
      At any point in time the PSU’s wouldn’t be loaded past say 30Amps for say a SSB HF TX.
      They generally idle around or under 5AMps.

      Appreciate any help.
      Contact me via my ham call (vk4akp) @ gmail, Facebook, Yahoo, Skype, etc etc.
      TNX, Ken

    The EEVblog Store generally ships twice a week, on Tuesdays & Fridays, Sydney time. Dismiss