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820-3209 no VCore

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TheoGa

New member
Hello guys,

I have no ppvcore signal on my 820-3209 board. I replaced U7400 and also Q7510, Q7520 and Q7550 but I had no luck. There is still no VCore signal (on L7510) and I can't figure out why.
I also replaced R7402 but still no luck (Pin1 of R7402 8.4V - Pin2 350mV).
When I plug the power cable in, I get a green light, orange light and also the fan spins.

I hope you can help me out!
Thanks a lot!!!
 
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TheoGa

New member
Yes, the Macbook officially doesn't run of the battery and the user just worked with it by using the power cord. Then the fans started to get louder and louder and finally, after 15 minutes the screen went black and the problem I mentioned above occurred.
 
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dukefawks

Administrator
Still I suspect the SMC. The fans running high indicated a sensor issue so could be SMC. Not running off battery is usually SMC.
The no Vcore is because the CPU is not talking to U7400 to set the output voltage. There are 100 reasons for the CPU not to run of course. Is ALL_SYS_PWRGD present?
 
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TheoGa

New member
Hello,
yes I have 3.3V on ALL_SYS_PWRGD!
Do you thing replacing the SMC from a donor board would fix that issue?
 
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dukefawks

Administrator
Cannot say anything for sure. No Vcore can have 100 different causes. I base my SMC diagnoses on the fact that it also did not work from battery. But it could easily be anything else.
 
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TheoGa

New member
So, I now replaced the SMC and the board start working again, thanks a lot dukefawks.

The thing which is suspicious to me is that after I put the logicboard in my ultrasonic cleaner like every other board, I had no green light (no onewire) anymore.
When I check the onewire circuit with U7000, I have these values:

- pin 19 & 20 (VCC) = present
- pin 3 (ACIN) = 4.4V
- pin 13 (CHGR_RST_L) = 0V
- pin 14 (CHGR_ACOK) = 0V

for testing purposes, I replaced U7000 but nothing changed.

Does someone have an idea what could be bad?

Thank you!
 
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dukefawks

Administrator
CHGR_RST_L is low so probably SMC_RESET is low too. Remove J5100 for a start, then check corrosion around U5010 and value of R5000.
Of course disconnect trackpad cable first to rule that out!
 
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TheoGa

New member
Hello,

yes SMC_RESET is low.

I now removed J5100 and replaced U6990 because I thought that this chip could be bad because I get only 1V on the boost pin. (nothing changed)
Why do I only get 1V boost with a new chip? Would it be possible that my replaced SMC went bad during the ultrasonic cleaning?

Then I replaced U5010 as well as R5000 and C6998. (nothing changed)
 
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TheoGa

New member
Yes, I measure a short to GND too (on 3V42), but I can´t figure out where. Would it be possible that there is corrosion under my newly soldered SMC after ultrasonic cleaning?
 
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