iMac G5 gurus - Please help - C903 keeps bulging

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • Player2
    Senior Member
    • Aug 2009
    • 98
    • USA
    #1

    iMac G5 gurus - Please help - C903 keeps bulging

    Hello all,

    I've been reading the forums here for some time, and I've acquired a great deal of knowledge here. This is my first time posting though.

    I've got here two iMac G5 motherboards, with ambient light sensor, no iSight. Part no. 820-1747-A. I recapped both of them with Nichicon HZ caps. After running each of them in a test computer for 24 hours, both of them are bulging the same cap. The location in question is C903, in the grouping below the RAM slots. Value is 1800 uF @ 6.3v. I replaced the cap again on the first board, tested again, bulged again.

    Is this a common problem? Is the silk screen on the board wrong? I am positive that I installed the cap correctly, according to the board. Any help is greatly appreciated!
    Tags: None
    • kc8adu
      Super Moderator
      • Nov 2003
      • 8829
      • U.S.A!
      #2
      Re: iMac G5 gurus - Please help - C903 keeps bulging

      fire it up and check voltage at these caps.check polarity too.

        Comment

        • Toasty
          Badcaps Legend
          • Jul 2007
          • 4171
          #3
          Re: iMac G5 gurus - Please help - C903 keeps bulging

          Pictures of the failing caps area please. Pull the cap(s) and get a clear pic of the board silkscreen also.

          There should be plus(+) signs on the board. The stripe on caps is the negative(-).

          Looking at the board with the RAM to the right with the caps below, if this is the version with the coil to the left of the caps, then both those caps should have the striped side pointed towards the RAM slots.

          Check your power supply also. If it's from the same pre-2006 batch, it will probably have blown caps also.

          Toast
          veritas odium parit

            Comment

            • Player2
              Senior Member
              • Aug 2009
              • 98
              • USA
              #4
              Re: iMac G5 gurus - Please help - C903 keeps bulging

              Thank you both for your replies. It turned out I did reverse the polarity (three times! ) There is a + symbol on the - side of the cap, however it was for the small cap immediately adjacent which I did no replace. It's working fine now. If only all manufacturers would just shade in the negative side of the pad...

              I did replace all of the caps in the PSU as well and it's working great.

                Comment

                • ratdude747
                  Black Sheep
                  • Nov 2008
                  • 17136
                  • USA
                  #5
                  Re: iMac G5 gurus - Please help - C903 keeps bulging

                  Good job! imacs are not cheap... drop some cash on caps and you have a better imac than a brand new stock one could ever be. should be just like you first got it.
                  sigpic

                  (Insert witty quote here)

                    Comment

                    Previous template Next

                    Related Topics

                    Collapse
                    • ryogadan78
                      iMac A1418 - No LED, no power after overvoltage on Ethernet port
                      by ryogadan78
                      Hi guys, I need your help again.
                      I have this iMac from a customer that shut down during a storm along with all the other devices in the house. In particular, the router, connected via Ethernet to the iMac, caught fire.
                      When I removed the screen from the iMac to check the status of the LEDs, I noticed that none of them were lit. I had a perfectly compatible and working power supply, so I tried it right away, but the problem remained the same (no LEDs). With the thermal camera, I noticed only a slight warming (32 degrees) of the NCP1605BG chip on the power supply. The rest was completely...
                      06-10-2025, 03:49 AM
                    • Stephen
                      iMac M1 DFU restore issue
                      by Stephen
                      iMac turns on no drops no cracks, tried to DFU Restore the iMac, logo turns on great! however iMac turns itself off and then restarts to the (!) icon and won't post the restore. Tried thunderbolt 3 cable, tried regular USB C cable and nothing.

                      this is the message it gives me with the error

                      Unexpected device state 'DFU' expected 'RestoreOS' (Probably forced into DFU mode externally) [com.apple.MobileDevice.MobileRestore – 0xFAE (4014)].


                      Any thoughts what this could be? I will open it up and repair it but I am not 100% sure since this iMac doesn't...
                      03-07-2025, 12:19 PM
                    • Stephen
                      iMac 27” 2020 Boot issue
                      by Stephen
                      Customer came in for data recovery, came to find out data is soldered on to this iMac (learn something new everyday) this is a 2020 T2 iMac so I was surprised because the iMac Pro has a T2 chip and it isn’t soldered on. Anyways, the iMac boots to Apple logo and then restarts, before it turns off you hear a quarter fan spin then it repeats itself. I decided to do a DFU revive to restore any hardware firmware issues and it was successful in reviving the device however the issue persists in boot looping. It shows the Apple logo for like 40 seconds then turns off and fan spin rinse repeat. I...
                      08-16-2024, 09:32 AM
                    • tommy97
                      iMac Pro 2017 A1862 SSD Upgrade & Recovery mode
                      by tommy97
                      Hi,

                      we've got iMac Pro 2017 which having a problem with SSD, iMac come with 2 SSD's 1TB, it was having a problem with the SSD so we get the replacement, installed in and iMac is stuck in recovery mode, tried to restore it & revive, nothing worked - error 4010. After installing old drives now we're having the same problem that the device is in recovery mode. Previously after swap of the SSD iMac worked on the old SSD however after attempt of revive on the new SSD machine stuck in recovery mode, I can go to DFU but the same result with error 4010.

                      Any ideas what might've...
                      04-20-2024, 04:48 AM
                    • howardc64
                      A1312 (27” iMac 2009-2011) A1407 (Thunderbolt Display) A1316 (Cinema Display) Display Black Screen Repair
                      by howardc64
                      Problem

                      This is an LG edge LED lit LCD Display. The LEDs are on the bottom edge of the display. There are 2 bars (left and right) Each bar has many LEDs and a 6 pin connector. Each pin drive several LEDs thus is the highest current flow / heat junction. The weak lead free solder gradually fails with thermal expansion/contraction cycling and increases resistance. PSU will compensate up to a point, then when the current is too high, PSU just shut down the backlight causing a dark display. I have even seen one which the connector just fell off as solder points became completely detached....
                      08-04-2024, 10:36 PM
                    • Loading...
                    • No more items.
                    Working...