Checking my PSU's +5VSB rail

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  • flexy123
    Member
    • Dec 2012
    • 34
    • Spain

    #1

    Checking my PSU's +5VSB rail

    Hello,

    Problem:

    I have a ca. 6 year old TT Toughpower 750W. I run into the problem that my PC is not booting up anymore, so now I do testing to find out whether the problem is with the PSU or the mobo. I have limited resources, although I have a DMM.

    The problem seems related to my +5VSB rail and the fact that as soon as the PSU is plugged into the board, nothing works anymore.

    When i "paperclick jump" the PSU unplugged, PSU starts up and I can measure all rails fine and the voltages look allright. (It can also power my fans, drives etc. as long as the 20pin ATX is not plugged into the board and the board is paperclip jumpered).

    Now...for some primitive "load test" I have a 5V light bulb which lights up on the +5V rail

    But when I do this test on the +5VSB (purple wire) of the PSU, the bulb is NOT lighting up and the PSU is not going on either, instead I hear a very faint 50hz (?) ticking inside the PSU.

    This also happens when I plug the PSU in the board.

    Can I assume that if that primive bulb test works on the normal +5V rail, it should also work on the +5VSB....so this is a strong indication that the PSU is defective? (I just opened the PSU as well but dont see anything odd like bulging caps or similar)

    I just need a halfway reliable way to make sure it's really my PSU and not the board.

    ***

    Additional info:

    When I plug in the PSU to the board, PS_ON measures 1.83 (which should be more like 0) and +5VSB measures 2.6V - also, the SB_PWR LED on the board is "flickering" (not blinking!) which looks like 50hz flickering to me. And I also hear that faint 50hz "ticking" inside the PSU.

    Given my rather amateurish knowledge, my current assumption is that the problem is PSU related, eg. +5VSB breaks in as soon as there is some load? (Still puzzled it displays fine in the DMM if nothing is plugged it to the PSU tho).
    Last edited by flexy123; 12-07-2012, 06:30 AM.
  • flexy123
    Member
    • Dec 2012
    • 34
    • Spain

    #2
    Re: Checking my PSU's +5VSB rail

    Edit: When I run my *LED case light* using the +5VSB line, it's fine.

    Now I am all the way back to the beginning with suspecting it's rather a mobo issue than a PSU issue.

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #3
      Re: Checking my PSU's +5VSB rail

      When you use the incadescent lamp for testing, you will have to watch out for the cold resistance of the lamp which will be 10 times less resistance than when it is hot. Your 5V STBY may be rated at 2~3A, so the cold resistance should not be less than 1.7 Ohms (@5V 3A) otherwise it may cause the power suply to go into over current shutdown. Check the resistance of the lamp you are using. You should use 2 Ohms 20W resistor instead
      Never stop learning
      Basic LCD TV and Monitor troubleshooting guides.
      http://www.badcaps.net/forum/showthr...956#post305956

      Voltage Regulator (LDO) testing:
      http://www.badcaps.net/forum/showthr...999#post300999

      Inverter testing using old CFL:
      http://www.badcaps.net/forum/showthr...er+testing+cfl

      Tear down pictures : Hit the ">" Show Albums and stories" on the left side
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      TV Factory reset codes listing:
      http://www.badcaps.net/forum/showthread.php?t=24809

      Comment

      • c_hegge
        Badcaps Legend
        • Sep 2009
        • 5219
        • Australia

        #4
        Re: Checking my PSU's +5VSB rail

        I'll bet that thing as a bad 5vsb input cap. I had one just like it fry the board because if that.
        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

        • flexy123
          Member
          • Dec 2012
          • 34
          • Spain

          #5
          Re: Checking my PSU's +5VSB rail

          I am not having any spare resistors here otherwise I would have long built some simple load tester.

          However, I had the idea to put a loudspeaker across the wire (+5VSB/GND) which is measured at 4 Ohm, assuming it might be "ok" to simulate load due to lack of resistors....

          Anyway, with the 4 Ohm speaker across the wire, the +5VSB *is* breaking down and I can then also hear the 50hz on the +5VSB oscillating from the speaker. (Sounds very much like a lawn mower)

          Preliminary conclusion: PSU can't handle load on +5VSB since it should NOT break in/shut down with the 4 Ohm resistance?

          Comment

          • ben7
            Capaholic
            • Jan 2011
            • 4059
            • USA

            #6
            Re: Checking my PSU's +5VSB rail

            Originally posted by flexy123
            I am not having any spare resistors here otherwise I would have long built some simple load tester.

            However, I had the idea to put a loudspeaker across the wire (+5VSB/GND) which is measured at 4 Ohm, assuming it might be "ok" to simulate load due to lack of resistors....

            Anyway, with the 4 Ohm speaker across the wire, the +5VSB *is* breaking down and I can then also hear the 50hz on the +5VSB oscillating from the speaker. (Sounds very much like a lawn mower)

            Preliminary conclusion: PSU can't handle load on +5VSB since it should NOT break in/shut down with the 4 Ohm resistance?
            The loudspeaker '4ohm' resistance is the IMPEDANCE, NOT the DC resistance!

            Open up the PSU, and take some pictures!
            Muh-soggy-knee

            Comment

            • flexy123
              Member
              • Dec 2012
              • 34
              • Spain

              #7
              Re: Checking my PSU's +5VSB rail

              Ok, I am a fool

              BUT: C_HEGGE is my hero!

              I just found a thread by him in another forum where he had the same PSU as i have, with a bulged cap on the +5VSB.

              http://forums.hardwaresecrets.com/not-so-tough/8805

              So today I took another close look inside my PSU, this *very same* cap is without a question bulged!

              So yes I took some pictures but it's pointless, it is without a doubt bulged, it's the +5VSB line and it would explain everything. Now to get one of those caps!!

              (My mistake was to look for "obvious" signs like busted etc. caps....so I didn't catch that cap at the first glance....but seeing the pics he posted and googling "bulged caps" there is no question that it bulges up).

              Edit: And yes I agree, it's a shame because that PSU was not "cheap" by a long-shot.
              Last edited by flexy123; 12-08-2012, 09:33 AM.

              Comment

              • flexy123
                Member
                • Dec 2012
                • 34
                • Spain

                #8
                Re: Checking my PSU's +5VSB rail

                THANK YOU GUYS!

                Without your forum and in particular C_Hegge's post I would never have found what was wrong with my PC.

                Today, I recapped the PSU (my first recap job, by the way) - I didn't want to wait til Tuesday until I got the right cap in the mail. I took two 1200uF 16V and put them parallel - and the PSU and my comp is working again! Yes it was that darn +5VSB input cap!

                I had another bizarre situation after the cap job, I booted into Win7 fine. Shut down PC and moved the old one back and the fixed one back in place.

                Low and behold, the next time i turn it on:NOTHING. I spent another several hours troubleshooting and got mad because I knew that the comp was just working and the PSU was fixed. UNTIL I found a tiny piece of metal shavings on the board....

                Long story short: PSU working again, PC working again.

                The bulged cap looked pretty bad, and I am lucky it did NOT fry my mobo as in c_hegge's post...

                I am VERY happy since I was about to get a new motherboard - ONLY with the help of you guys in the forum I took a second look at that cap from c_hegge's post and could fix the PSU and everything now!
                Last edited by flexy123; 12-09-2012, 02:03 PM.

                Comment

                • TELVM
                  Badcaps Veteran
                  • Oct 2012
                  • 547
                  • Spain

                  #9
                  Re: Checking my PSU's +5VSB rail

                  ¡Enhorabuena!

                  What was the brand of that busted +5VSB cap?

                  Comment

                  • flexy123
                    Member
                    • Dec 2012
                    • 34
                    • Spain

                    #10
                    Re: Checking my PSU's +5VSB rail

                    Samxon <--

                    Likely some dud series which TT used 5-6 years ago in their PSUs....

                    Comment

                    • c_hegge
                      Badcaps Legend
                      • Sep 2009
                      • 5219
                      • Australia

                      #11
                      Re: Checking my PSU's +5VSB rail

                      Yup. The cap in my one was a GF series
                      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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