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    #1

    faulty power supply?

    Hello Everyone,

    I have a generic power supply which is supposedly rated at 400W but i doubt it. Well it works fine, apart from high fan noises, but theres this issue with radio distorsion? when i turn on my radio, i can hear something like a buzzing noise, which is loud and also annoying, especially when im listening to a talk show if i turn off the PC, it goes away.
    The caps are all fine, but has anyone got any ideas to what is causing this? Faulty transformer maybe? My father reckons that the manufacturer probably snitched some copper wire from the transformer to save money (not sure there) so it's causing this distortion. Though he may be right since it gets pretty hot when in use. Anyone got ideas to whats wrong? I have 2 Power units with the same issue, both different brands, theres this "TT" brand 400W PSU and an "N.S" 250W Power supply with the same noise across radio issue.


    Thanks.
    Don't find love, let love find you. That's why its called falling in love, because you don't force yourself to fall, you just fall. - Anonymous
    Tags: None
    #2
    Re: faulty power supply?

    What brand are the caps?
    To me it sounds like noise is being injected into the lines somewhere.
    Find Nedry!


    Check the Vending machines!!

    <----Computer says I need more beer.

    Comment

      #3
      Re: faulty power supply?

      The cheap Deer/Powmax/Allied/... PSUs with fake ratings (anything over 250W) usually have all the EMI/RFI components missing - inductors/transformers will be jumpered, and caps will be left unpopulated. That's what causes Radio-Frequency Interference, and these PSUs are illegal for use in most parts of the world, but slip through anyway due to lax enforcement.

      Comment

        #4
        Re: faulty power supply?

        Absent pix of the miscreant P/S, I'd guess linux nailed it. If you open the thing, you're likely to find jumper wires in place of inductors and emptiness instead of X and Y caps (maybe tiny 1KV GP ceramic discs instead of real, safety-agency-rated Y caps). Keep in mind, however, that any switching P/S generates a certain amount of noise. So if your computer is right next to your radio, the problem is with that placement (3-4 feet of separation should suffice with a decent P/S and system case).
        PeteS in CA

        Power Supplies should be boring: No loud noises, no bright flashes, and no bad smells.
        ****************************
        To kill personal responsibility, initiative or success, punish it by taxing it. To encourage irresponsibility, improvidence, dependence and failure, reward it by subsidizing it.
        ****************************

        Comment

          #5
          Re: faulty power supply?

          Thanks PeteS in CA, but the PC is no-where near the radio, it's probably more than 15 metres away from the radio. I tried it on a different power outlet, which is rated at 240V 15A, it is supposed to be for the Air conditioner, but i can still hear it even though the A/C line is a completely sepearate line.... and even has it's own circuit breaker. So i think that it is probably interfering with all the lines in the house, albeit from that, as i can remember (Long While ago) , i could feel some numbness as i touched the PSU at times.
          I'm guessing there is an electricity leak somewhere even though the power cord has a ground/earth on it, but my Circuit breaker and safety switch hasnt budged yet so i guess it is still safe.

          Thanks.
          Don't find love, let love find you. That's why its called falling in love, because you don't force yourself to fall, you just fall. - Anonymous

          Comment

            #6
            Re: faulty power supply?

            That's a terrible psu!
            Change it as soon as you can.
            Yes, the numbness does mean an electrical leak (or in this case, a hot frame)
            Find Nedry!


            Check the Vending machines!!

            <----Computer says I need more beer.

            Comment

              #7
              Re: faulty power supply?

              numbness ? ur computer PSU is not properly earthed. Is the EARTH connection OK ? All SMPS has line filter / EMI filter to eliminate noise, both common mode and diferential mode. It uses comon mode coil and couple of X capacitors (usually X2), although some uses X1 capacitor. There are 2 disc type capacitor connects the L and N line to EARTH. These 2 capacitor cause very small leakage current (unless the cap failed) to the EARTH. If ur equipment is properly earthed, you should not feel any numbness.

              Comment

                #8
                Re: faulty power supply?

                I got some bad news.... i found Hermei and Koshin caps in there?!
                Don't find love, let love find you. That's why its called falling in love, because you don't force yourself to fall, you just fall. - Anonymous

                Comment

                  #9
                  Re: faulty power supply?

                  Ok, thank you everyone for the advice, i have included some images if that helps at all. I know i shouldnt have opened it when i had just unplugged it, but anyhow, it works still. There are Hermei and Koshin caps in there. There are also 2 470uf 200V caps that dont have a name and only some logo.
                  Can anyone help me on identifiyng the unknown name caps?

                  Any ideas on how to fix this PSU? recapping maybe? but what about those 200V caps? im not game enough to recap those, i think they hold a current somewhere in there.


                  Thanks.
                  Attached Files
                  Don't find love, let love find you. That's why its called falling in love, because you don't force yourself to fall, you just fall. - Anonymous

                  Comment

                    #10
                    Re: faulty power supply?

                    It actually appears to have a AC filter integrated on the PCB right at the AC input, however it does look geniunley crap

                    That is a Deer rebranded PSU, it is not saft to use (and in many countries illegal to even sell)

                    Do yourself, your computer and possibly your houses fire insurance some good by buying a new powersupply (good brand, see recommendations here in Badcaps in other threads)

                    The PSU is in many ways unfit, not only is it just unsafe, it comes no where near to it's rated "400w" output, maybe 200-250 if you are really lucky... The reason it's getting so hot is that it is already being overloaded...

                    Your Pentium4 CPU wants current on the +12v line but this PSU has been made for older computers that pulled mainly from the +5v line.

                    Sorry to be so harsh but it really is a crap PSU and not worth to fix...

                    EDIT; just realized that maybe it's not driving the computer in your sig, anyway, it's still not a good PSU :P
                    "The one who says it cannot be done should never interrupt the one who is doing it."

                    Comment

                      #11
                      Re: faulty power supply?

                      Thanks Per Hansson, yeah i was guessing this PSU was crap since the day i used it, though at first i thought it was really good because it had that 24 Pin Pentium 4 plug, but a few months ago i decided it was too unreliable for use with the PC in my signature because of voltage fluctuations, so i bought a new ThermalTake Mambo and Thermaltake 430W power supply for that PC, this PSU is currently in my Pentium III 800EB as a folding at home PC.... but i may reconsider buying a new one due to the risks it carries.

                      Well i was planning to be a little adventurous into fixing this crap PSU.....

                      This PSU didnt cost me $30AUD, but it's $30AUD retail. I got it as a case/PSU package thing for $65AUD about 1 year ago.

                      Thanks.
                      Last edited by stevo1210; 01-02-2007, 05:27 AM.
                      Don't find love, let love find you. That's why its called falling in love, because you don't force yourself to fall, you just fall. - Anonymous

                      Comment

                        #12
                        Re: faulty power supply?

                        There is a thread somewhere here in the forums where it's explained what you need to exchange to make the PSU decent, it's basically the whole thing :P

                        And buying only single parts will probably cost you more than it's worth to put into that POS...
                        "The one who says it cannot be done should never interrupt the one who is doing it."

                        Comment

                          #13
                          Re: faulty power supply?

                          Yep, it isn`t worth the trouble. Any way, for your pII 800 it should be fine. Trodas has some excelent thread abouth a shody psu he recaped. If you replace all caps, especiallay those smaler ones i mean 10uf /25v to 20uF/50v ones is criticall, to prevent that this unit will fry your components. To eliminate that RFI some bigger coils may be necesarry, as those are realy small.

                          Comment

                            #14
                            Re: faulty power supply?

                            Well, I can see a common mode inductor (hopefully there's a toroid core inside that plastic outer case). There's a film cap next to it that might be an X-cap, though I doubt it. Don't see any differential mode inductors, though the common mode inductor will contribute some differential mode inductance, due to the way it's wound. And I don't think I see any Y-caps - I'm assuming those dark disc components near the AC wires are thermistors. So it has a little EMI filtering, but nowhere near enough. Switching P/Ss inherently generate EMI, so the presence of interference with your radio is not an indicator of a bad P/S so much as of the lack of EMI filter.
                            Last edited by PeteS in CA; 01-02-2007, 06:53 PM.
                            PeteS in CA

                            Power Supplies should be boring: No loud noises, no bright flashes, and no bad smells.
                            ****************************
                            To kill personal responsibility, initiative or success, punish it by taxing it. To encourage irresponsibility, improvidence, dependence and failure, reward it by subsidizing it.
                            ****************************

                            Comment

                              #15
                              Re: faulty power supply?

                              The coil is rather wimpy, compared with eny cheap psu of a seriouse brand (e.g. FSP 250MDM or Seasonic SS300FS). I doubt that this combination can filter enough RFI to get any cert it should have. I doubth that the enigeners are smarter than those from Delta, FSP & Seasonic and have found a mutch cheaper way to comply with EMI regulations. But any way, there may be are other problems wich can cause RFI problems.

                              Comment

                                #16
                                Re: faulty power supply?

                                The Y-caps are located at the pcb edge, near Ac inlet.

                                [/URL][/IMG]

                                Comment

                                  #17
                                  Re: faulty power supply?

                                  There is a simple test you can do to rule out RFI: Turn up your radio's volume; if noise get louder too, is RFI since it enters trough the antenna to the preamp, amp, speakers etc. I don't know any cheap solution to this problem other than getting a good new PSU.
                                  Good luck!!

                                  Comment

                                    #18
                                    Re: faulty power supply?

                                    Another thing of consideration is the "RFI rejection" specs of your radio. Have you tried with another radio in your premises?

                                    Comment

                                      #19
                                      Re: faulty power supply?

                                      Thanks Wilfredom,

                                      I have tried it with many radios available in my house and it still happens.... as i can remember, it got louder as the volume on the radio got louder.
                                      Anyone got sugesstions to a cheap - mid priced power supply that is actually safe and mediocre in terms of quality?

                                      Thanks.
                                      Don't find love, let love find you. That's why its called falling in love, because you don't force yourself to fall, you just fall. - Anonymous

                                      Comment

                                        #20
                                        Re: faulty power supply?

                                        The Fortron/Source brand is a good place to start
                                        "The one who says it cannot be done should never interrupt the one who is doing it."

                                        Comment

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