As I said, the PMU from 01041 board worked for me.
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820-01700 (A2141) R7900 failed, power cycling after R7900 bridged
- Thread starter cchamberlain
- Start date
cchamberlain
New member
Hi, I just wanted to provide a final update and to say that unfortunately I'm going to have to abandon the repair.
I reballed the chip I bought from see-ic which is supposedly compatible with the 01041 board, and this time the reball was good. However, after installing it on the board I went back to the same pulsing PPBUS which I had last time this chip was fitted and a short from L7810 to ground. At that time I postulated that maybe I had a short between the BGA solder balls but this time the soldering went really well with leaded solder so I think maybe the chip itself is faulty. That could have been caused by my original attempt at installing it where I didn't use a high enough temperature to melt the lead-free solder but probably applied the heat for too long.
As a last ditch attempt, I decided to try to reball the PMU chip I recovered from the 01814 board but the solder mask was starting to break down due to repeated repair attempts and it was just bridging all over the place. There was no way I could apply solder balls again because the balls were just flowing into what should have been masked. I hate to give up on anything but sometimes you just have to call it a day! I've got too many other demands on my time to keep going.
I've learned a lot and I want to thank you for your help and patience. I have no doubt that the fault was with U7800 which subsequently blew R7900, but I took too many attempts to gain the skill required to complete the repair successfully.
Plan B is unfortunately to get Apple to replace the logic board and after that I'll probably sell the machine and buy a MacBook Air instead. I don't really want to continue to be the owner of a 01700 board now that I know how many issues they have!
Kind regards,
Craig.
I reballed the chip I bought from see-ic which is supposedly compatible with the 01041 board, and this time the reball was good. However, after installing it on the board I went back to the same pulsing PPBUS which I had last time this chip was fitted and a short from L7810 to ground. At that time I postulated that maybe I had a short between the BGA solder balls but this time the soldering went really well with leaded solder so I think maybe the chip itself is faulty. That could have been caused by my original attempt at installing it where I didn't use a high enough temperature to melt the lead-free solder but probably applied the heat for too long.
As a last ditch attempt, I decided to try to reball the PMU chip I recovered from the 01814 board but the solder mask was starting to break down due to repeated repair attempts and it was just bridging all over the place. There was no way I could apply solder balls again because the balls were just flowing into what should have been masked. I hate to give up on anything but sometimes you just have to call it a day! I've got too many other demands on my time to keep going.
I've learned a lot and I want to thank you for your help and patience. I have no doubt that the fault was with U7800 which subsequently blew R7900, but I took too many attempts to gain the skill required to complete the repair successfully.
Plan B is unfortunately to get Apple to replace the logic board and after that I'll probably sell the machine and buy a MacBook Air instead. I don't really want to continue to be the owner of a 01700 board now that I know how many issues they have!
Kind regards,
Craig.