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Power supply build quality pictorial. part 2

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    Re: Power supply build quality pictorial. part 2

    Couldn't get that great of a pic with my phone but you can see where I desoldered the CapXon input caps. I should be able to use the holes right next to them? They're on the same trace, just spaced out farther, it's a perfect width for the OST's. Pretty sure it would work but I just wanna get your guys' input (no pun intended)
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      Re: Power supply build quality pictorial. part 2

      Yeap, I have done that before with success.

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        Re: Power supply build quality pictorial. part 2

        Originally posted by goodpsusearch View Post
        Yeap, I have done that before with success.
        Nice. And the old holes don't need to be filled?

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          Re: Power supply build quality pictorial. part 2

          Originally posted by Pentium4 View Post
          Nice. And the old holes don't need to be filled?
          Not really. You could apply some solder to make them look nice though

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            Re: Power supply build quality pictorial. part 2

            Originally posted by Th3_uN1Qu3 View Post
            YC for me too.
            YC for me three. Of course, if given choice between Ost and YC, I'll definitely take Ost.

            Originally posted by tom66
            CapXon and Teapo are probably honest as they are seen in most consumer stuff too, not cheap power supplies. I don't think you could long get away with lying about capacitance if you were selling to everyone.
            Not quite. It depends.
            In my experience, low-voltage CapXon are indeed honest about their capacitance ratings and like goodpsusearch said, they do meet their specs.
            The high-voltage CapXons aren't as honest, though. I measured a pair of 330uF caps from an old J&C PSU and they both showed 220uF +/- 3uF. IMO, that's too close to 220uF to say that age was the cause for this result.

            And if that's not enough of a reason to avoid CapXon high voltage caps, I have seen at least 3 threads pop up here on badcaps.net where the problem was dried up (and sometimes open-circuited) CapXon high voltage caps. IIRC, those were PSU threads, and in each case the APFC circuit bombarded when the CapXon primary caps died.

            The low-voltage CapXon caps also suck, so I say just avoid CapXon when possible. I only keep a few "good" looking ones for temporarily replacing obviously failed caps.

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              Re: Power supply build quality pictorial. part 2

              Originally posted by momaka View Post
              YC for me three. Of course, if given choice between Ost and YC, I'll definitely take Ost.


              Not quite. It depends.
              In my experience, low-voltage CapXon are indeed honest about their capacitance ratings and like goodpsusearch said, they do meet their specs.
              The high-voltage CapXons aren't as honest, though. I measured a pair of 330uF caps from an old J&C PSU and they both showed 220uF +/- 3uF. IMO, that's too close to 220uF to say that age was the cause for this result.

              And if that's not enough of a reason to avoid CapXon high voltage caps, I have seen at least 3 threads pop up here on badcaps.net where the problem was dried up (and sometimes open-circuited) CapXon high voltage caps. IIRC, those were PSU threads, and in each case the APFC circuit bombarded when the CapXon primary caps died.

              The low-voltage CapXon caps also suck, so I say just avoid CapXon when possible. I only keep a few "good" looking ones for temporarily replacing obviously failed caps.
              Yeah I put the OST in. It says 560uF 200V but was exactly to the MM the same size as the 470uF 200V YC. Recapped the whole thing except less than 10uf caps. I wonder if especially changing the input caps with better ones and the secondary will change the output voltage. Before I recapped it (with 1 bulging cap) it was reading 11.7V on the 12V. What you said about high voltage CapXon's not being honest sounds about right. I have a OCZ GameXstream 700W that a friend gave me that has a bulging CapXon primary cap. Granite, it had APFC but it was powering a low load computer. Core 2 Duo, 9800GT, 2 hard drives. If I recall correctly, it claimed to be a 450uF, 400V cap
              Last edited by Pentium4; 09-26-2012, 07:23 PM.

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                Re: Power supply build quality pictorial. part 2

                ^If anything, PFC puts less stress on primary caps than non-PFC systems. So a CapXon that can't manage a job as a PFC bulk cap is a very poorly made cap.

                I've said it before - I think a lot of these bad cap issues are simply poor quality. Like maybe 5-10% of CapXon fail before their rated lifespan. And the specs are "improved" by the marketing department. It often only takes one bad cap to take a device down.
                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.

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                  Re: Power supply build quality pictorial. part 2

                  Originally posted by tom66 View Post
                  ^If anything, PFC puts less stress on primary caps than non-PFC systems. So a CapXon that can't manage a job as a PFC bulk cap is a very poorly made cap.

                  I've said it before - I think a lot of these bad cap issues are simply poor quality. Like maybe 5-10% of CapXon fail before their rated lifespan. And the specs are "improved" by the marketing department. It often only takes one bad cap to take a device down.
                  Really?? I thought it was the other way around. Yeah, I don't think it matters whether these cheap caps are 105C or 85C rated they're going to fail quickly either way it seems..

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                    Re: Power supply build quality pictorial. part 2

                    Originally posted by tom66 View Post
                    ^If anything, PFC puts less stress on primary caps than non-PFC systems. So a CapXon that can't manage a job as a PFC bulk cap is a very poorly made cap.
                    I was always told that even Passive PFC generates more heat and I've heard of 820uF 200V Teapos dying after 5 years of being in close proximity to a passive PFC - it was suspected that the hot PFC was the reason for their death. Does PFC somehow take stress off primary capacitors even though they're definitely not as stressed as other capacitors in the PSU to begin with? And I would say 105C and 85C capacitors are far and apart in what they can take, all things considered.... (with exception to exceptionally crappy capacitors)

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                      Re: Power supply build quality pictorial. part 2

                      APFC boosts the voltage on the input caps, that's the reason they use lower uF primary caps when there is APFC. This stresses input caps more than PPFC or no PFC at all. PPFC, I don't know, maybe it generates heat.

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                        Re: Power supply build quality pictorial. part 2

                        I always *thought* APFC stresses the input caps the most because of the large voltage spikes generated by the APFC coil and the high frequency of the circuit. But that's only my logic and I may be wrong.

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                          Re: Power supply build quality pictorial. part 2

                          Originally posted by momaka View Post
                          I always *thought* APFC stresses the input caps the most because of the large voltage spikes generated by the APFC coil and the high frequency of the circuit. But that's only my logic and I may be wrong.
                          That's what I thought too, cause even terrible caps seem to last ages on the primary. The only caps where I've had the primaries fail in a non APFC PSU were Fuhjyyu and Teapo, and a Taicon in a gigabit switch.

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                            Re: Power supply build quality pictorial. part 2

                            What were the specs of the Teapos that failed as input capacitors for you? Usually, unless something is stressing them or literally "toasting" them, they do okay as primary capacitors for a while, at least I thought they would.

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                              Re: Power supply build quality pictorial. part 2

                              Teapoo are just lame to begin with.
                              "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                              -David VanHorn

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                                Re: Power supply build quality pictorial. part 2

                                I know this is a topic discussed upon before in this thread, but I was thinking... if the second diode of a bipolar transistor or MOSFET (TO-220/TO-247 respectively) on the secondary is used as a freewheeling (or flyback) diode in single and two-transistor forward topology (thus not sharing the load evenly and contributing less, hence the lower output rating than the full one of the rectifier), and if it has nothing to do with duty cycle (thus not contributing 30-40% less as those on Hardware Secrets say), how much less would it be than the full rating (or rather, how much percent does the flyback diode contribute, or does it vary drastically)?

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                                  Re: Power supply build quality pictorial. part 2

                                  Going off the top of my head, the typical usage of a double diode in SMPSs with half-wave rectified output is 70%.
                                  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!

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                                    Re: Power supply build quality pictorial. part 2

                                    Is that 70% of the whole rectifier or 70% of one of the two diodes?

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                                      Re: Power supply build quality pictorial. part 2

                                      70% of the whole.
                                      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!

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                                        Re: Power supply build quality pictorial. part 2

                                        So then, if you tried to pull the whole rating of the rectifier in forward topology, would it work (in a stressed manner) or would the unit theoretically shut down since it thinks it exceeded its maximum on whatever rail (if there was OCP/OVP/OPP)?
                                        Last edited by Wester547; 09-29-2012, 04:13 PM.

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                                          Re: Power supply build quality pictorial. part 2

                                          Well the rectifier doesn't have a current rating, it would just run hotter and have a shorter lifespan. I imagine if you run a rectifier in excess of its current rating for too long it will simply fail.
                                          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.

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