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    COMPUSA 250 watt ATX power supply

    If my power supply goes bad, is it a good idea to go down to my local CompUSA store and buy a replacement? Here is a "used" CompUSA 250 watt ATX power supply which I have recently acquired.

    Looks like lots of bulging capacitors. So I applied power to see what the 5vsb was doing. It came up a little over 5 volts. Good start, but thought I would change the bulging output capacitors before proceeding. All were Rulycon brand. Here is what I found:

    2200 uF/10V 1.5 (esr)
    2200 uF/10V 2.0
    2200 uF/10V 1.7
    1000 uF/16V 2.8
    1000 uF/16V 3.5
    470 uF/16V 8.6

    1000 uF/10V 4.4 (5vsb filter)

    Since ALL of these output capacitors were obviously bad, do you think the non-bulging smaller caps are bad (same brand)? I thought Fuhjyyu were the worst brand of capacitors, but I have never seen a psu where ALL of the capacitors were bad.

    Main pwm chip is AP3843B and supervisor chip is marked Bestec B850. 5vsb switching transistors are K3067 and C945, common 2 transistor 5vsb circuit. Marking on 5vsb transformer is LP6100D. With no model number or OEM label, I wonder who made this psu....L&C, Bestec, or .........???

    With output caps replaced, power came up fine as follows:
    12V 12.03V
    5V 5.25V
    3.3V 3.38V
    5vsb 5.02V

    However, as I was monitoring and watching the 12 volt rail, the voltage varied from 12.02V to 12.73V, back and forth for a while. Finally seems to have settled at 12.03V. Maybe those little caps need replacement too!

    The 12V and 5V output rails have PI filters, but the 3.3V looks somewhat lacking.

    The QC label indicates this psu was manufactured July 2001. Overall, I would not have trusted it as a replacement. Would you?
    Attached Files
    Old proverb say.........If you shoot at nothing, you will hit nothing (George Henry 10-14-11)

    #2
    Re: COMPUSA 250 watt ATX power supply

    It's a leadman LP6100, the old version.

    Looks like there is room on the 3.3v for another cap, pi coil, and a choke.

    Comment


      #3
      Re: COMPUSA 250 watt ATX power supply

      Replace all caps on this unit. Rulycon is a Rubycon knock-off brand so I wouldn't trust any of those caps, not even the smallest ones.
      As far as the voltage fluctuation, check the primaries. Mine had JEEs and after they bulged, the voltages started to fluctuate a lot too.
      It might also be a good idea to put a heatsink on the main 5vsb transistor - it really does get hot, along with few resistors around it. That 5vsb critical cap (25v 47uF) probably gets cooked pretty well because it's positioned right in that area.
      There's a few other odd things I noticed about the 5vsb as well and this is consistent with my LP6100 - 5vsb circuit is missing components ZD1, R50, C34, and R35. Also look at the glass diode next to J13 - doesn't really correspond to what's written on the PCB. Any idea why? To me it looks like this was originally some kind of dedicated circuit for powering the supervisory chip, but I guess they removed it to save valuable cents.
      I say this one is a good candidate for the 5vsb mod .

      Other than that, this PSU is okay. It doesn't seem overrated either. I had mine (CompUSA, '500w' model) for close to 5 years (was used only 4-6 hours a day, though) and didn't have a problem until the capacitors bulged.

      By the way, what's that burn mark in the first picture? It looks like something arced.

      Comment


        #4
        Re: COMPUSA 250 watt ATX power supply

        I don't trusted it as a replacement too, even replaced all caps with good brand.
        too risky to my whole system, because 2 transistors 5Vsb.
        | AMD Phenom II X2 550BE | GIGABYTE GA-MA790FXT-UD5P | GeIL DDR3 Ultra 2x2GB 1600C7 |
        | XFX GTS250 DDR3 512MB | Dell H525EF-00 | Lancool PC-K62 Black | Samsung 2232GW |
        | 2xWD7500AYYS | 2xHD322GJ Raid0 |

        Comment


          #5
          Re: COMPUSA 250 watt ATX power supply

          Good ol' CompUSA.

          *sniffs* I planned (when I was like 14) to go work there as my first job. Then they closed.

          Comment


            #6
            Re: COMPUSA 250 watt ATX power supply

            I used a Compusa PSU on my old HP 300mhz PC in my basement once. One of those SFX form factor PSUs. Well long story short the fan died and all the caps bloated.

            However the PSU didn't die so I recapped it and replaced the fan with a Silenx fan. The Panaflo ball bearing ones were just too noisy for me.

            It was very quiet and the PC performed well for awhile then the Silenx fan died and so did the PSU. The caps didn't bloat this time though proving how crappy the old ones were.

            Rather than fix this piece of crap again I finally junked it.

            Good riddance Compusa!!! I hope you died a slow and painful death.

            Does anyone remember Computer City? I loved that store years ago.

            Nowadays the only computer specialty store that comes close is Microcenter. I can't get OEM HDDs locally anywhere else.
            Last edited by Krankshaft; 11-28-2009, 01:46 AM.
            Elements of the past and the future combining to make something not quite as good as either.

            Comment


              #7
              Re: COMPUSA 250 watt ATX power supply

              oh god that is a POS powersupply! rulycon neds to be made rulyGONE! add chockes, etc.
              sigpic

              (Insert witty quote here)

              Comment


                #8
                Re: COMPUSA 250 watt ATX power supply

                >Would you?

                nope.

                Comment


                  #9
                  Re: COMPUSA 250 watt ATX power supply

                  I usually try to find something good to say about even the worst power supply. For this one, I am in agreement with ratdude747, it is a POS. As somewhat of a joke, I replaced those Rulycon capacitors with pullout Fuhjjyu capacitors, ones that tested good on Blue ESR meter. The power supply works so much better now! I doubt this power supply will ever again provide power to a computer - at least not one of mine!!!

                  I4004 - I totally agree with your opinion - totally untrustworthy power supply. I enjoyed your opinion - the shortest response I have ever seen you make.....just one word. I'm sure pcbones will be proud of you.

                  On to more serious stuff - I have a Antec Smart Power SP400 that I am recapping. It had lots of Fuhjjyu caps. Most disappointing, the primary caps are 820 uF/200 volt Fuhjjyu caps. It also has the 5vsb two transistor circuit ... will have to do my special add on DM311 board.

                  As for the CompUSA 250 watt psu, there is NOTHING in it I can see as having any value, even for parts.
                  Old proverb say.........If you shoot at nothing, you will hit nothing (George Henry 10-14-11)

                  Comment


                    #10
                    Re: COMPUSA 250 watt ATX power supply

                    Originally posted by everell
                    As for the CompUSA 250 watt psu, there is NOTHING in it I can see as having any value, even for parts.
                    The heatsinks are alright - about as thick as any other decent PSU in that watt range. They're held with screws too so they can be removed pretty easily. I've seen better-built PSUs with crappier heatsinks, and this could definitely be an upgrade for one of them.
                    But you're right, there's not much other than that.

                    Comment


                      #11
                      Re: COMPUSA 250 watt ATX power supply

                      CompUSA used to get PSUs from everybody, one time even from Win-tact, a supplier to PCP&C.

                      Comment


                        #12
                        Re: COMPUSA 250 watt ATX power supply

                        btw. what's this
                        http://pdf1.alldatasheet.com/datashe...IP/AP3843.html
                        doing there?
                        amplifying the feedback from the secondary?

                        >I'm sure pcbones will be proud of you.

                        anything for him!
                        <wink>

                        Comment


                          #13
                          Re: COMPUSA 250 watt ATX power supply

                          The AP3843 is the main pwm chip - different manufacturer from the usual U3843 pwm chip. The pwm is on the primary side driving the main switchers. Notice that there is not a third transformer. Just one transformer for switcher output and one transformer for the 5vsb. The supervisory chip is the one marked "Bestec" probably same as the TPS3510 family. One of the isolator chips couples the feedback signal to the AP3843 chip. Not a bad design concept, just cheaply built from start to finish, especially with choice of capacitors.

                          Both transformers are very small. Even the Bestec series are better......larger transformers and better built. The Bestec can be improved upon.......but this one only has decent heat sinks. That just isn't enough to start with.
                          Old proverb say.........If you shoot at nothing, you will hit nothing (George Henry 10-14-11)

                          Comment


                            #14
                            Re: COMPUSA 250 watt ATX power supply

                            Originally posted by everell
                            I usually try to find something good to say about even the worst power supply. For this one, I am in agreement with ratdude747, it is a POS. As somewhat of a joke, I replaced those Rulycon capacitors with pullout Fuhjjyu capacitors, ones that tested good on Blue ESR meter. The power supply works so much better now! I doubt this power supply will ever again provide power to a computer - at least not one of mine!!!

                            I4004 - I totally agree with your opinion - totally untrustworthy power supply. I enjoyed your opinion - the shortest response I have ever seen you make.....just one word. I'm sure pcbones will be proud of you.

                            On to more serious stuff - I have a Antec Smart Power SP400 that I am recapping. It had lots of Fuhjjyu caps. Most disappointing, the primary caps are 820 uF/200 volt Fuhjjyu caps. It also has the 5vsb two transistor circuit ... will have to do my special add on DM311 board.

                            As for the CompUSA 250 watt psu, there is NOTHING in it I can see as having any value, even for parts.
                            scrap wire and plugs perhaps.

                            or maybe even a DOORSTOP!

                            as for the antec, dang, talk about ritzy shit. people that use it think they are so great but really are not. at least with a-power/powmax, the people know they are cheapskates.

                            Abominable
                            Nasty
                            Terrible
                            Expensive
                            Crappy

                            ANTEC!
                            sigpic

                            (Insert witty quote here)

                            Comment


                              #15
                              Re: COMPUSA 250 watt ATX power supply

                              Originally posted by ratdude747
                              scrap wire and plugs perhaps.

                              or maybe even a DOORSTOP!

                              as for the antec, dang, talk about ritzy shit. people that use it think they are so great but really are not. at least with a-power/powmax, the people know they are cheapskates.

                              Abominable
                              Nasty
                              Terrible
                              Expensive
                              Crappy

                              ANTEC!
                              Dude, some Antecs aren't half bad. As with almost every other retail brand, the quality varies wildly from one product to the next. Yeah they had their Fuhjyuu fuckup. Nichicon had their HN/HM fiasco, UCC has KZGs popping left and right, etc., etc.. You can't dismiss an entire brand from one bad series of products.

                              Comment


                                #16
                                Re: COMPUSA 250 watt ATX power supply

                                >Notice that there is not a third transformer.

                                yes, in such cases usually 3 optocouplers appear instead...
                                if one is for +5vstby feedback, the other for "usual" feedback, i thought 3rd one is redundancy for 2nd one(?)
                                i don't have such psu handy to inspect....and i'm too lazy to inspect pcb traces from your pics...hehe....

                                Comment


                                  #17
                                  Re: COMPUSA 250 watt ATX power supply

                                  Optocouplers:
                                  One normally used for voltage regulation of output rails (+5v, +12V, +3.3v)
                                  One normally used for voltage regulation of 5vsb
                                  One used for power fault protection (FPO signal from supervisory chip, sometimes PGO signal), it shuts down the pwm chip
                                  On some Bestec models, a fourth optoisolator used to control SCR crowbar circuit to shut down 5vsb from overvoltage if all else fails
                                  Old proverb say.........If you shoot at nothing, you will hit nothing (George Henry 10-14-11)

                                  Comment


                                    #18
                                    Re: COMPUSA 250 watt ATX power supply

                                    excellent, thanks.

                                    Comment


                                      #19
                                      Re: COMPUSA 250 watt ATX power supply

                                      Originally posted by weirdlookinguy
                                      Dude, some Antecs aren't half bad. As with almost every other retail brand, the quality varies wildly from one product to the next. Yeah they had their Fuhjyuu fuckup. Nichicon had their HN/HM fiasco, UCC has KZGs popping left and right, etc., etc.. You can't dismiss an entire brand from one bad series of products.
                                      'Dude'
                                      Antec has had FAR FAR more than 'one bad product' and the difference is they do it deliberately in aid of penny pinching and then falsely advertise it as a premium product.
                                      - They've been pulling that crap for almost 10 years now.
                                      My own personal reviews of some 2008 & 2009 built Earthwatts PSU's indicates they haven't changed one bit. Also looking at published reviews of the same models it appears they wait until enough reviews hit the web for the model THEN 'cost it down' further in main stream production.

                                      Antec is an unscrupulous untrustworthy company. - End of story.

                                      Now, if you are willing to recap them then Antec PSUs are usually very good.
                                      - But that doesn't mitigate the fact that, as a company, Antec is a Shit-bag with absolutely no Integrity.
                                      .
                                      Mann-Made Global Warming.
                                      - We should be more concerned about the Intellectual Climate.

                                      -
                                      Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

                                      - Dr Seuss
                                      -
                                      You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                                      -

                                      Comment


                                        #20
                                        Re: COMPUSA 250 watt ATX power supply

                                        Originally posted by PCBONEZ
                                        Also looking at published reviews of the same models it appears they wait until enough reviews hit the web for the model THEN 'cost it down' further in main stream production.
                                        .
                                        Can you explain that?

                                        thnx

                                        Comment

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