Sansun SN-W450 ATX - buzzing & burn marks

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  • quattro alex
    Senior Member
    • Mar 2012
    • 92
    • UK

    #1

    Sansun SN-W450 ATX - buzzing & burn marks

    Model:Sunsung "make your life beautiful" SN-W450 ATX
    Sticker: 0604 005 263

    Fault: Buzzing heard with the psu powered on without load. Probably still buzzing with load but intake fan too noisy to hear.

    Background: Work colleague asked me to take a look at this psu which he has had for a few years, he mentioned the buzzing and the fact it looked quite dusty - this was an understatement.

    Testing / observations:

    PSU (cheap tester) showed the following rail voltages:
    +3.3 = 3.3v
    +5 = 5.2v
    +12v1 = 12.1v
    +12v2 = 12.1v
    -12v = 11.6v
    5vsb = 5.1
    PSG=280ms (not sure what this means)

    Once I'd removed a lot of the dust I saw that caps C19 & C20 were bulging. These are JEE caps with a value of 2200UF and 10 volts. Tested values were ESR of 2.2 & 2.3, no capacitance value available - I am assuming it was too low. I still have to measure a few of the other caps (Canicon and Su'Scon)

    At this stage I had a sniff and I could smell that burnt plastic smell. I unscrewed the secondary board which sat upside down above the 2 large black caps. This didn't look so good - the pcb was very discoloured around 2 resisters. I need some help trying to work out the values of these resisters as the colour bands are badly burnt. There is also no continuity on either of the resisters.

    I will carry on testing the remaining resisters that I can work the values out on. The general layout on this psu seems quite poor and everything seems very tightly squeezed in. Add copious amounts of dust and this can't make for a long service life.

    Photo's to follow shortly.
    Fixed so far: GNR TS902W monitor, Sony Game Gear, Philips FCD565, Arcam Alpha 10, Memorex SA 404amp
  • quattro alex
    Senior Member
    • Mar 2012
    • 92
    • UK

    #2
    Re: Sansun SN-W450 ATX - buzzing & burn marks

    photo's now attached
    Attached Files
    Fixed so far: GNR TS902W monitor, Sony Game Gear, Philips FCD565, Arcam Alpha 10, Memorex SA 404amp

    Comment

    • everell
      Badcaps Legend
      • Jan 2009
      • 1514
      • USA

      #3
      Re: Sansun SN-W450 ATX - buzzing & burn marks

      Does the fan blade spin freely? If not, a good place to start would be to take the fan apart, clean and oil the bushing, then reassemble. Without a freely spinning fan, I would expect lots of continuing heat problems.
      Old proverb say.........If you shoot at nothing, you will hit nothing (George Henry 10-14-11)

      Comment

      • c_hegge
        Badcaps Legend
        • Sep 2009
        • 5219
        • Australia

        #4
        Re: Sansun SN-W450 ATX - buzzing & burn marks

        Those resistors won't get much airflow, even with a working fan. I think that the best solution would be to disable the APFC and remove the PBC (although I don't know if that's legal in the UK, since PFC is mandatory there). As for the buzzing, it's probably the two big caps going bad. JEE are a notoriously unreliable brand and APFC puts more stress on them than usual.
        I love putting bad caps and flat batteries in fire and watching them explode!!

        No wonder it doesn't work! You installed the jumper wires backwards

        Main PC: Core i7 3770K 3.5GHz, Gigabyte GA-Z77M-D3H-MVP, 8GB Kingston HyperX DDR3 1600, 240GB Intel 335 Series SSD, 750GB WD HDD, Sony Optiarc DVD RW, Palit nVidia GTX660 Ti, CoolerMaster N200 Case, Delta DPS-600MB 600W PSU, Hauppauge TV Tuner, Windows 7 Home Premium

        Office PC: HP ProLiant ML150 G3, 2x Xeon E5335 2GHz, 4GB DDR2 RAM, 120GB Intel 530 SSD, 2x 250GB HDD, 2x 450GB 15K SAS HDD in RAID 1, 1x 2TB HDD, nVidia 8400GS, Delta DPS-650BB 650W PSU, Windows 7 Pro

        Comment

        • Th3_uN1Qu3
          Believe in
          • Jul 2010
          • 6031
          • Romania

          #5
          Re: Sansun SN-W450 ATX - buzzing & burn marks

          Originally posted by c_hegge
          Those resistors won't get much airflow, even with a working fan. I think that the best solution would be to disable the APFC
          Or use resistors with proper power rating.
          Originally posted by PeteS in CA
          Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
          A working TV? How boring!

          Comment

          • b700029
            Banned
            • Sep 2010
            • 640

            #6
            Re: Sansun SN-W450 ATX - buzzing & burn marks

            280ms is the time from power-on to when the Power Good signal comes up.

            It looks a lot better than some "500W" gutless wonder, and some of the newer high-wattage PSUs are just as cramped inside. Poor choice of caps though.

            For figuring out the value of the resistors you can pull the endcaps off and try measuring the resistance across the carbon spiral directly. They might not be directly responsible, but something else failed in the APFC circuit may have caused them to overheat.

            Comment

            • tom66
              EVs Rule
              • Apr 2011
              • 32560
              • UK

              #7
              Re: Sansun SN-W450 ATX - buzzing & burn marks

              The buzzing could be bad primary caps. I had a PSU that did that when the primary caps were bad - then again, they were only fake 330uF ones (actually 220uF.)
              Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
              For service manual, schematic, boardview (board view), datasheet, cad - use our search.

              Comment

              • quattro alex
                Senior Member
                • Mar 2012
                • 92
                • UK

                #8
                Re: Sansun SN-W450 ATX - buzzing & burn marks

                The fan spins, but could definitely be smoother, so I will take it apart and use something like lubricating oil for a shredder.

                Big JEE 85c (CE.W IM0610) caps are rated at 820uf and 200v - tested at no1. 840uf & 0.17 esr. No2.770uf & 0.20 esr - I haven't got these, what would be a good replacement and what level of ripple should I be aiming for?

                I got a reading for both resisters using the 200K scale on my DMM. 1.374 & 1.376 - can you recommend which value I should replace these with?

                APFC - does this stand for automatic power filtering control? I don't know about the regulations regarding this, and I am not sure I'd feel comfortable removing it - especially as this is not my equipment.

                Thank you for all the advice / suggestions so far.
                Attached Files
                Fixed so far: GNR TS902W monitor, Sony Game Gear, Philips FCD565, Arcam Alpha 10, Memorex SA 404amp

                Comment

                • mcdaydavies
                  Senior Member
                  • Jun 2011
                  • 77
                  • UK

                  #9
                  Re: Sansun SN-W450 ATX - buzzing & burn marks

                  I think APFC means active power factor correction.

                  Comment

                  • PeteS in CA
                    Badcaps Legend
                    • Aug 2005
                    • 3579
                    • USA, Unsure of Planet

                    #10
                    Re: Sansun SN-W450 ATX - buzzing & burn marks

                    That's what it is, mcday. Without power factor correction (PFC) the voltage charge on big input lytics mean that the P/S only draws current from the AC line during the very brief parts of the 50Hz or 60Hz sine when the voltage at the input is higher than the voltage across the caps. If you saw the input current on an oscilloscope you would see alternating, brief, high amplitude, positive- and negative-going spikes with relatively long periods between during which little or no current flows. Ideally, PFC allows current to flow throughout the sine wave cycle, in phase with the voltage, with sinusoidal amplitude.

                    Active PFC comes close to achieving that ideal, but requires and extra controller (or a dual controller), an extra switch device, an extra rectifier, and an extra inductor. Passive PFC doesn't come as close to the ideal, but is much simpler - a large, heavy, steel laminations core inductor between the bridge rectifier and the input lytics. Active PFC is usually wide range, capable of operating from 120VAC (nominal) or 240VAC (nominal) without setting a voltage range switch. A P/S with Passive PFC requires a range switch.
                    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

                    • b700029
                      Banned
                      • Sep 2010
                      • 640

                      #11
                      Re: Sansun SN-W450 ATX - buzzing & burn marks

                      The primary caps are within tolerance. They're usually +/- 20% so 820uF could mean anywhere from 656 to 984uF. They are probably JEE LM series ( http://www.jee-jee.com/huizhou/digit...id=1437&bb=eng ) although their catalog indicates they should be violet and not black.

                      The resistors might be 137K.

                      Comment

                      • c_hegge
                        Badcaps Legend
                        • Sep 2009
                        • 5219
                        • Australia

                        #12
                        Re: Sansun SN-W450 ATX - buzzing & burn marks

                        ^
                        The capacitance is probably OK, but the ESR seems a bit high

                        Originally posted by Th3_uN1Qu3
                        Or use resistors with proper power rating.
                        The burned resistors look to be fairly beefy, so unless you go with larger power resistors, higher wattage ones may not be available.
                        I love putting bad caps and flat batteries in fire and watching them explode!!

                        No wonder it doesn't work! You installed the jumper wires backwards

                        Main PC: Core i7 3770K 3.5GHz, Gigabyte GA-Z77M-D3H-MVP, 8GB Kingston HyperX DDR3 1600, 240GB Intel 335 Series SSD, 750GB WD HDD, Sony Optiarc DVD RW, Palit nVidia GTX660 Ti, CoolerMaster N200 Case, Delta DPS-600MB 600W PSU, Hauppauge TV Tuner, Windows 7 Home Premium

                        Office PC: HP ProLiant ML150 G3, 2x Xeon E5335 2GHz, 4GB DDR2 RAM, 120GB Intel 530 SSD, 2x 250GB HDD, 2x 450GB 15K SAS HDD in RAID 1, 1x 2TB HDD, nVidia 8400GS, Delta DPS-650BB 650W PSU, Windows 7 Pro

                        Comment

                        • quattro alex
                          Senior Member
                          • Mar 2012
                          • 92
                          • UK

                          #13
                          Re: Sansun SN-W450 ATX - buzzing & burn marks

                          My colleague is looking to keep the cost down so I'll hold fire on replacing the primary caps for the moment. With regard to the resistors is it likely that their resistance has decreased or increased over time?

                          I am concerning about getting the correct wattage. When I look online the 137k 0.25w resistors don't look beefy enough. The measurements of the resistors are 11.1mm long by 3.5mm diameter, lead wire of 0.74mm. Is it likely that these would be 2w or higher in rating?

                          Is something like this suitable? http://uk.rs-online.com/web/p/throug...fixed/2142235/
                          Fixed so far: GNR TS902W monitor, Sony Game Gear, Philips FCD565, Arcam Alpha 10, Memorex SA 404amp

                          Comment

                          • Th3_uN1Qu3
                            Believe in
                            • Jul 2010
                            • 6031
                            • Romania

                            #14
                            Re: Sansun SN-W450 ATX - buzzing & burn marks

                            They are likely to be over 1W, i think 3W ones will fit.
                            Originally posted by PeteS in CA
                            Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                            A working TV? How boring!

                            Comment

                            • quattro alex
                              Senior Member
                              • Mar 2012
                              • 92
                              • UK

                              #15
                              Re: Sansun SN-W450 ATX - buzzing & burn marks

                              What are the risks of going with a higher wattage?
                              Fixed so far: GNR TS902W monitor, Sony Game Gear, Philips FCD565, Arcam Alpha 10, Memorex SA 404amp

                              Comment

                              • Th3_uN1Qu3
                                Believe in
                                • Jul 2010
                                • 6031
                                • Romania

                                #16
                                Re: Sansun SN-W450 ATX - buzzing & burn marks

                                Risk of going with higher wattage: Might not fit due to larger physical dimensions.
                                Risk of going with lower wattage: Suffer the same fate as the original ones (burn out).
                                Originally posted by PeteS in CA
                                Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                                A working TV? How boring!

                                Comment

                                • Behemot
                                  Badcaps Legend
                                  • Dec 2009
                                  • 4845
                                  • CZ

                                  #17
                                  Re: Sansun SN-W450 ATX - buzzing & burn marks

                                  As for the APFC, I got some dealing with our business inspection (basicly tried to get them ban some crappy PSU, it is just fine according to them - they must be corrupted) and learned that no standard defines use of PFC in EU. There are only restriction for backward harmonic emissions, but I think that could be mostly get rid of by proper filtration. The PFC is just easy way to do that, and as for higher power-rated PSU's, you have to use APFC to not blow of your breakers all the time (cause you get higher current consumption without PFC).

                                  As for the resistors, what about doing some flymod or attaching them to heatsink? :-)
                                  Less jewellery, more gold into electrotech industry! Half of the computer problems is caused by bad contacts

                                  Exclusive caps, meters and more!
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                                  Comment

                                  • c_hegge
                                    Badcaps Legend
                                    • Sep 2009
                                    • 5219
                                    • Australia

                                    #18
                                    Re: Sansun SN-W450 ATX - buzzing & burn marks

                                    Originally posted by Th3_uN1Qu3
                                    I think 3W ones will fit.
                                    They may fit, but the ones in there look like 3W, so they will just do exactly the same thing.

                                    If I wasn't going to disable APFC, I would use some 10W wire-wound resistors, use some Thermal Epoxy to stick them to a heat sink (assuming the PSU has one which isn't live) and use wires to connect them to the PCB.
                                    I love putting bad caps and flat batteries in fire and watching them explode!!

                                    No wonder it doesn't work! You installed the jumper wires backwards

                                    Main PC: Core i7 3770K 3.5GHz, Gigabyte GA-Z77M-D3H-MVP, 8GB Kingston HyperX DDR3 1600, 240GB Intel 335 Series SSD, 750GB WD HDD, Sony Optiarc DVD RW, Palit nVidia GTX660 Ti, CoolerMaster N200 Case, Delta DPS-600MB 600W PSU, Hauppauge TV Tuner, Windows 7 Home Premium

                                    Office PC: HP ProLiant ML150 G3, 2x Xeon E5335 2GHz, 4GB DDR2 RAM, 120GB Intel 530 SSD, 2x 250GB HDD, 2x 450GB 15K SAS HDD in RAID 1, 1x 2TB HDD, nVidia 8400GS, Delta DPS-650BB 650W PSU, Windows 7 Pro

                                    Comment

                                    • Th3_uN1Qu3
                                      Believe in
                                      • Jul 2010
                                      • 6031
                                      • Romania

                                      #19
                                      Re: Sansun SN-W450 ATX - buzzing & burn marks

                                      10W resistors are huge... 5W will do.
                                      Originally posted by PeteS in CA
                                      Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                                      A working TV? How boring!

                                      Comment

                                      • c_hegge
                                        Badcaps Legend
                                        • Sep 2009
                                        • 5219
                                        • Australia

                                        #20
                                        Re: Sansun SN-W450 ATX - buzzing & burn marks

                                        ^ Maybe, but it's still too close to the original 3W rating. If you're attaching them with wires, size is no big deal. There's room for a pair of 10W resistors there on the APFC heat sink. I used a few for the 5vsb and 12V rails on my load tester. I didn't think they were that big.
                                        I love putting bad caps and flat batteries in fire and watching them explode!!

                                        No wonder it doesn't work! You installed the jumper wires backwards

                                        Main PC: Core i7 3770K 3.5GHz, Gigabyte GA-Z77M-D3H-MVP, 8GB Kingston HyperX DDR3 1600, 240GB Intel 335 Series SSD, 750GB WD HDD, Sony Optiarc DVD RW, Palit nVidia GTX660 Ti, CoolerMaster N200 Case, Delta DPS-600MB 600W PSU, Hauppauge TV Tuner, Windows 7 Home Premium

                                        Office PC: HP ProLiant ML150 G3, 2x Xeon E5335 2GHz, 4GB DDR2 RAM, 120GB Intel 530 SSD, 2x 250GB HDD, 2x 450GB 15K SAS HDD in RAID 1, 1x 2TB HDD, nVidia 8400GS, Delta DPS-650BB 650W PSU, Windows 7 Pro

                                        Comment

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