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Corsair GS800 Power Supply Problem

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    #21
    Re: Corsair GS800 Power Supply Problem

    Originally posted by R_J View Post
    where do you see voltages on the secondary?
    He is still getting like 0.1v or something, I don't think that would be there with an open gate drive resistor.

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      #22
      Re: Corsair GS800 Power Supply Problem

      Originally posted by CapLeaker View Post
      He is still getting like 0.1v or something, I don't think that would be there with an open gate drive resistor.
      R116 is the source resistor for Q11, I wanted to see if it was open or not, turns out it is good.

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        #23
        Re: Corsair GS800 Power Supply Problem

        I also see Q7 has an insulating kit and Q11 does not, has it been changed to an insulated mosfet? I hope it's drain is not connected to the heatsink. or is Q11 an original and Q7 been replaced with something else?
        Last edited by R_J; 04-04-2020, 07:58 PM.

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          #24
          Re: Corsair GS800 Power Supply Problem

          I just checked the pictures again and you are correct on the resistor, I also did notice that Q7 and Q11 are different, one is a full pack the other isn’t. There is insulating hardware on Q7, but either it is bad, or Q7 is bad. Do Q7 and Q11 have the same part number?

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            #25
            Re: Corsair GS800 Power Supply Problem

            Originally posted by R_J View Post
            If D13 cathode is 377v and D19 cathode is 377v then Q7 is either turned on or shorted.
            D13 cathode connects to Q7 Drain
            D19 cathode connects to Q7 Source
            Q11 original if I remember correctly. Q7 was sourced from another PS
            Removed Q7 and it is not shorted. Yes Q7 does have insulating mounting hardware. I will run an independent bench test on this and see if it is good.

            It does appear .19 volts is making it through the transformer to the secondary side for the 12v rail.

            Q7:


            Q11:
            Attached Files
            Last edited by Per Hansson; 04-10-2020, 03:50 AM. Reason: Offsite image uploaded

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              #26
              Re: Corsair GS800 Power Supply Problem

              I would also check the resistance of the primary of the transformer, If you have +377v on D19 cathode, you should also have that voltage on D13 anode, and you do not.
              Attached Files
              Last edited by R_J; 04-04-2020, 08:29 PM.

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                #27
                Re: Corsair GS800 Power Supply Problem

                Feedback winding continuity.
                Primary open.
                Neg side of primary winding to feedback is 11 megaohm.
                Last edited by ShortCircuited; 04-04-2020, 09:00 PM.

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                  #28
                  Re: Corsair GS800 Power Supply Problem

                  Originally posted by ShortCircuited View Post
                  Feedback winding continuity.
                  Primary open.
                  Neg side of primary winding to feedback is 11 megaohm.
                  That would do it. open primary

                  Comment


                    #29
                    Re: Corsair GS800 Power Supply Problem

                    When the original Q7 shorted it took the primary winding with it? Unfortunately, I don't think these transformers can be sourced reasonably cheap.

                    Here is the suspect as oriented from the board bottom-view:
                    Attached Files
                    Last edited by Per Hansson; 04-10-2020, 03:48 AM. Reason: Offsite image uploaded

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                      #30
                      Re: Corsair GS800 Power Supply Problem

                      Have a close look at the wires that connect to the pins, sometimes it can break right where it connects to the pin.

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                        #31
                        Re: Corsair GS800 Power Supply Problem

                        Solder joints look good. Primary winding is actually two wires whereas the feedback is only one wire.

                        Curious. If I am getting .19 on the secondary side that suggests the primary winding broke early in the wind?

                        Is it possible to fix this transformer? If i could find the opening a small bead of solder would be an acceptable fix? It appears the outside is glued together:
                        Attached Files
                        Last edited by Per Hansson; 04-10-2020, 03:48 AM. Reason: Offsite image uploaded

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                          #32
                          Re: Corsair GS800 Power Supply Problem

                          Check the primary winding to those pins that are cut off, I suspect there might be a thermal fuse in the primary. I marked where it might be, but it could also be between the other cutoff pin. check the resistance between those pins, the transformer might be fixable.
                          You posted a picture of the secondary side, But post a similar picture of the PRIMARY side. I might be able to tell if there is an imbeded fuse
                          Attached Files
                          Last edited by R_J; 04-05-2020, 10:19 AM.

                          Comment


                            #33
                            Re: Corsair GS800 Power Supply Problem

                            Originally posted by R_J View Post
                            Check the primary winding to those pins that are cut off, I suspect there might be a thermal fuse in the primary. I marked where it might be, but it could also be between the other cutoff pin. check the resistance between those pins, the transformer might be fixable.
                            You posted a picture of the secondary side, But post a similar picture of the PRIMARY side. I might be able to tell if there is an imbeded fuse
                            Feedback Yellow: .78
                            Primary Green: 1
                            Thermal Fuse Red: open
                            Might be here Blue: 1

                            Primary Side:
                            Attached Files
                            Last edited by Per Hansson; 04-10-2020, 03:50 AM. Reason: Offsite image uploaded

                            Comment


                              #34
                              Re: Corsair GS800 Power Supply Problem

                              an open primary would do it alright. As RJ already said, check the thermal fuse in the primary, if it has one.

                              Comment


                                #35
                                Re: Corsair GS800 Power Supply Problem

                                BINGO! Pin 5 (per post 33) has two wires and one is cracked/split. Looks like QC issue. The wire was not long enough during the manufacturing process and came up short it appears...so just add a glob of solder? Friday Build. I never would have found that without you guys. OH CANADA...!
                                Attached Files
                                Last edited by Per Hansson; 04-10-2020, 03:49 AM. Reason: Offsite image uploaded

                                Comment


                                  #36
                                  Re: Corsair GS800 Power Supply Problem

                                  Good find, BUT is the power supply going to work? lets hope so.

                                  Comment


                                    #37
                                    Re: Corsair GS800 Power Supply Problem

                                    Originally posted by R_J View Post
                                    Good find, BUT is the power supply going to work? lets hope so.
                                    Stop now while we are ahead...? Will post results in a few hours....

                                    Fixed break and we now have continuity across the primary winding as originally predicted.
                                    Last edited by ShortCircuited; 04-05-2020, 11:37 AM.

                                    Comment


                                      #38
                                      Re: Corsair GS800 Power Supply Problem

                                      very good find! keep my fingers crossed that it works after you reassembled it.

                                      Comment


                                        #39
                                        Re: Corsair GS800 Power Supply Problem

                                        Preliminarily it works!!!!!!!
                                        Tremendous ty


                                        12.2v
                                        5.0v
                                        3.3
                                        Last edited by ShortCircuited; 04-05-2020, 01:15 PM.

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                                          #40
                                          Re: Corsair GS800 Power Supply Problem

                                          awesome!

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