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Power Mac G4 MDD "Mirror-Door" won't power up

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    Power Mac G4 MDD "Mirror-Door" won't power up

    I have a second G4 that has decided not to power up. The fuse is NOT blown. When you press the power button, the power button's light turns on for as long as it is pressed, but from there, nothing happens. I have checked and I do get 25V on the 25V "trickle" line.

    This happened after a power outage. I have already tried pulling the NVRAM battery and pressing the CUDA switch. No difference. I therefore assume it's the power supply.

    This is the Apple P/N: 614-0224, Samsung PSCF401601.

    Any suggestions on where to go from here?

    #2
    Re: Power Mac G4 MDD "Mirror-Door" won't power up

    Measure the voltage on the battery, try unplugging the monitor. If it powers up with the monitor unplugged, plug it back in once it's on and see if it keeps running.

    Comment


      #3
      Re: Power Mac G4 MDD "Mirror-Door" won't power up

      Originally posted by cyclones
      I have a second G4 that has decided not to power up. The fuse is NOT blown. When you press the power button, the power button's light turns on for as long as it is pressed, but from there, nothing happens. I have checked and I do get 25V on the 25V "trickle" line.

      This happened after a power outage. I have already tried pulling the NVRAM battery and pressing the CUDA switch. No difference. I therefore assume it's the power supply.

      This is the Apple P/N: 614-0224, Samsung PSCF401601.

      Any suggestions on where to go from here?
      It's the PSU. MDDs had notoriously bad ones. Open it up and see if it had simultaneously thrown every cap like my Samsung one had, or if it's got a scorch on the back of the circuit board like another one I saw.

      Comment


        #4
        Re: Power Mac G4 MDD "Mirror-Door" won't power up

        Battery is 3.6V. I was already trying w/ monitor unplugged.
        Last edited by cyclones; 06-24-2010, 03:32 PM.

        Comment


          #5
          Re: Power Mac G4 MDD "Mirror-Door" won't power up

          Originally posted by iKitsune
          It's the PSU. MDDs had notoriously bad ones. Open it up and see if it had simultaneously thrown every cap like my Samsung one had, or if it's got a scorch on the back of the circuit board like another one I saw.
          It appears normal. Didn't notice anything odd when I had it open the other day. But I'm pretty sure you're right about it being bad.

          Comment


            #6
            Re: Power Mac G4 MDD "Mirror-Door" won't power up

            Samsung's on no-start are a few small caps down behind the PWM board next to the center/larger heatsink with the primary switchers on it. The little board is mounted upright next to the heatsink and the caps to be replaced require you to remove the entire heatsink and components. MIND THE THERMISTOR!!! Desoldering station makes it a 5 minute job. Wick and iron, 10 minutes.

            Again, check the primary cap as you have on the other G4. If it's CapXon HP, replace it. These can go "weak" and not blow the fuse or switchers.

            Toast
            veritas odium parit

            Comment


              #7
              Re: Power Mac G4 MDD "Mirror-Door" won't power up

              Is this panasonic a good model to replace the cRapXon cap?

              Manufacturer:
              PANASONIC
              Order Code:
              1198628
              Manufacturer Part No:
              EETED2G471EA
              RoHS : Yes
              Description
              CAPACITOR, 470UF, 400V
              Capacitor Dielectric Type:Aluminium Electrolytic
              Capacitance:470uF
              Capacitance Tolerance:± 20%
              Voltage Rating:400V dc
              Effective Series Resistance:282mohm
              Series:TSED
              Height:40mm
              Outside Diameter:35mm
              Capacitor Case Style:Radial Leaded
              No. of Pins:2
              Mounting Type:Snap-In
              Lead Spacing:10mm
              Operating Temperature Range:-25°C to +105°C
              AC Ripple Current:2.01A
              AC Ripple Current @ 120Hz:2.01A
              Application:High Temperature
              Body Diameter:35mm
              Case Style:Radial
              ESR Frequency:120Hz
              External Length / Height:40mm
              Max Operating Temperature:105°C
              Min Temperature Operating:-25°C
              Operating Lifetime:3000h
              PCB Hole Diameter:2mm
              Ripple Current Frequency:120Hz
              Ripple Current Temperature:105°C
              Terminal Type:Snap-In
              Tolerance, +:20%
              Tolerance, -:20%
              Voltage Rating DC:400V

              Thanks Toasty!

              Comment


                #8
                Re: Power Mac G4 MDD "Mirror-Door" won't power up

                [QUOTE=cyclones]Is this panasonic a good model to replace the cRapXon cap?

                Manufacturer:
                PANASONIC
                Order Code:
                1198628
                Manufacturer Part No:
                EETED2G471EA
                RoHS : Yes
                Description
                CAPACITOR, 470UF, 400V
                ------------
                Turns out I need 420V, but other than that is it OK?

                Comment


                  #9
                  Re: Power Mac G4 MDD "Mirror-Door" won't power up

                  why 420v?
                  rectified 240v - the highest you ever need is about 360vdc
                  a lot of mains caps are only rated at 380v

                  Comment


                    #10
                    Re: Power Mac G4 MDD "Mirror-Door" won't power up

                    Originally posted by stj
                    why 420v?
                    rectified 240v - the highest you ever need is about 360vdc
                    a lot of mains caps are only rated at 380v
                    420v is the rating on the original cap.

                    Comment


                      #11
                      Re: Power Mac G4 MDD "Mirror-Door" won't power up

                      Cyclones - Where are you located. Please fill out the location in your profile. Since that cap info seems to be a direct copy from Farnell....., Europe?


                      My choices have been Panasonic HB, HC; CDE 381L*; UCC KMQ (390uF/450v).

                      Toast
                      veritas odium parit

                      Comment


                        #12
                        Re: Power Mac G4 MDD "Mirror-Door" won't power up

                        Not in Europe; farnell was the first result that came up which had ripple current listed.
                        updated profile.

                        Comment


                          #13
                          Re: Power Mac G4 MDD "Mirror-Door" won't power up

                          Ooooo.....!

                          Tornado Alley!

                          Auntie Em!, Auntie Em!

                          veritas odium parit

                          Comment


                            #14
                            Re: Power Mac G4 MDD "Mirror-Door" won't power up

                            OK, so toasty are these the ones you speak of?
                            Attached Files

                            Comment


                              #15
                              Re: Power Mac G4 MDD "Mirror-Door" won't power up

                              Yes
                              veritas odium parit

                              Comment


                                #16
                                Re: Power Mac G4 MDD "Mirror-Door" won't power up

                                How the hell do you guys get those heatsinks out. There must be a way to pull the caps without taking it off. I can't see myself desoldering all that. what if you just unscrew the components and pull away the heatsink.

                                Comment


                                  #17
                                  Re: Power Mac G4 MDD "Mirror-Door" won't power up

                                  You are welcome to try, liebchen.
                                  Attached Files
                                  Last edited by Toasty; 06-28-2010, 11:52 PM.
                                  veritas odium parit

                                  Comment


                                    #18
                                    Re: Power Mac G4 MDD "Mirror-Door" won't power up

                                    Originally posted by JOHNBOY
                                    How the hell do you guys get those heatsinks out. There must be a way to pull the caps without taking it off. I can't see myself desoldering all that. what if you just unscrew the components and pull away the heatsink.
                                    You need a good desoldering iron. If you don't have one, it's a great investment. Without one, you might as well not even try. You want a vacuum one. A decent one (non-motor) is in the $50 range I think. The one I have was given to me as a gift. DON'T mess with the crappy bulb-type ones at radio shack. They're just above worthless.

                                    I'll post pictures of the board shortly that show which you need to desolder in order to get it out.

                                    The thermistor is a real b*tch. That is the only issue. So you must have everything desoldered fully and then SLOWLY work the heat sink up EVENLY.


                                    Also, here's an update. I replaced those three caps with new Panasonics and now the G4 powers up every time. THANKS TOASTY!!!!

                                    Comment


                                      #19
                                      Re: Power Mac G4 MDD "Mirror-Door" won't power up

                                      Excellent work! Thanks for posting the results & glad you got it fixed!

                                      Hint on the thermistor: Unsoldering it first relieves the tension on its legs. Make sure its wires are *completely free* in the holes. Then proceed to unsolder the rest of the components.

                                      Toast
                                      veritas odium parit

                                      Comment


                                        #20
                                        Re: Power Mac G4 MDD "Mirror-Door" won't power up

                                        Here are the photos as promised. Hopefully this will be helpful in the future.
                                        Attached Files

                                        Comment

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