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somehow my replacement R7121/22 were bad... replaced them now I get 20.8 ohms.

I replaced R7121/22 earlier and checked the traces between the ISL and R7121/22

U7100, C7121/22

Checked/replaced C7121/22, no change.

Don't give me answer, I will try to solve myself.

i did remove and check R7120, as mentioned above

No, getting 17.7K

and I meant I checked R7120

never mind about caps, was looking at a different board view

I checked R7020 off board and is still 0.2Ohms

Replaced R7021 and R7022 and resistance between pins 27 & 28 is 17.4K ohms

Did you mean C7021 and C7022?

Got it, will change other components first

I forgot to conform they were ok after I changed the ISL. SO be 20.2 Ohms, Won't forget this time. I just hope nothing else is blown. I may use a donor ISL this time to test.

I took them off the board to confirm. R7121 is "Open" and R7122 is 9.2K, so I would say they are bad as well

oops, yeah. R7121 is reading 625M and R7122 is 9.2K Will replace all three and report back. Weird thing happened too, when I turned it on something "popped" on the other side of the board.

So I replaced U7100 and it sounds like it blew again. The computer now turns on, but the resistance between 27 & 28 is .5M Ohms.

So I have on the bench an 820-00138, and the customer stated their customer used a knock off charger. The charger melted and now machine is dead. I have it on the bench and it is drawing 20mA, PP3V42 is preset but PPBUS is 4.2V. I measured pins 27 & 28 on U7100 and have 30K ohms, with pin 28...

Thank you for your reply. I ended up giving back to client as is was not worth the risk. They said they will send to Apple. Appreciate the help

as soon as it cools off back to blinking ? folder