Someone gave me this thing and it actually worked for a couple of days just fine and I was actually a bit impressed. A bad neutral connection in the local ac mains ckt in the apartment (which has since been repaired) was causing intermittent problems and I suspect contributed to the death of the PSU, with the ac mains cutting in and out several times. Even with the computer off there are active standby things alive (or rather, WERE alive) and it obviously didn't live through the ordeal, but perhaps was gonna blow anyway. Whatever. Doesn't matter at this point, it is dead now.
Mains fuse (10A/250V) is open. It's on a small board where what looks like a dual rectifier is, as well as two toroid coils and a few small caps and resistors, perhaps an MOV in there as well (there is so much damn glue all over things that are crammed into sardine can conditions that it's hard to tell). I checked the primary e-caps (820uF/200VDC/105c) and they seem fine but there is a dead short across the solder points/traces for one of the big caps with the cap removed. I traced it back up to the dual rectifier which appears to be a dead short on one side. I have been unable to find a schematic for the PSU. I have not removed the dual rectifier yet or checked any other components and I don't know the pinout on the rectifier.
I must say I really don't care for how Macs are put together. They have got to be the most difficult computer types I have ever worked on, and I have worked on literally TONS of computers as a tech for 30ish years. I'm retired and have forgotten more than I've learned. I am not a Mac hater though, a working computer is a working computer to me and if it is useful and/or fun it's fine by me. It was incredibly stupid to have to remove everything from inside the top half of the case just to get the PSU out though, and getting the boards out of the PSU was even more "fun". I swear that Apple purposefully made their stuff to be difficult to repair.
BTW, I need the 28Vdc output to power up the Studio Display that came with it. Also the onboard USB ports are physically broken so I need to use the USB ports on the Studio Display, so using a standard ATX PSU re-pinned is not going to cut it with this one.
Okay, lay the advice on me folks. Should I be looking at additional suspect parts or could it be just a case of a primary rectifier shorting out under dirty/intermittent power main conditions?
Apologies for the crappy pics. My wife keeps taking the camera from me before I can figure out how to get a good shot. LOL!
Mains fuse (10A/250V) is open. It's on a small board where what looks like a dual rectifier is, as well as two toroid coils and a few small caps and resistors, perhaps an MOV in there as well (there is so much damn glue all over things that are crammed into sardine can conditions that it's hard to tell). I checked the primary e-caps (820uF/200VDC/105c) and they seem fine but there is a dead short across the solder points/traces for one of the big caps with the cap removed. I traced it back up to the dual rectifier which appears to be a dead short on one side. I have been unable to find a schematic for the PSU. I have not removed the dual rectifier yet or checked any other components and I don't know the pinout on the rectifier.
I must say I really don't care for how Macs are put together. They have got to be the most difficult computer types I have ever worked on, and I have worked on literally TONS of computers as a tech for 30ish years. I'm retired and have forgotten more than I've learned. I am not a Mac hater though, a working computer is a working computer to me and if it is useful and/or fun it's fine by me. It was incredibly stupid to have to remove everything from inside the top half of the case just to get the PSU out though, and getting the boards out of the PSU was even more "fun". I swear that Apple purposefully made their stuff to be difficult to repair.
BTW, I need the 28Vdc output to power up the Studio Display that came with it. Also the onboard USB ports are physically broken so I need to use the USB ports on the Studio Display, so using a standard ATX PSU re-pinned is not going to cut it with this one.
Okay, lay the advice on me folks. Should I be looking at additional suspect parts or could it be just a case of a primary rectifier shorting out under dirty/intermittent power main conditions?
Apologies for the crappy pics. My wife keeps taking the camera from me before I can figure out how to get a good shot. LOL!
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