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Old 09-22-2021, 04:55 PM   #1
marce002
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Default a1286 Dead CPU ? No PPVCORE / No PP0V75_S0_DDRVTT

Hi

2011 a1286 820 2915-B , no water damage.

Turns fans on with keyboard attached (but reach max rpm after minute progressively), NO CHIME, USB mouse light up, removing memory no white led blinks nor beeps, onewire is fine green led then amber and charges ok.... but

Power Aliases manually checked all one by one and all in range!!

All present and in range except for:

PP1V5_S0 = Missing
PP0V75_S0_DDRVTT = Missing

CPU

PPVCORE_S0_CPU = Missing
PPVCORE_S0_AXG = Missing

I want someone to give me a way to determine if dead CPU here, not a clear and easy procedure to diagnose NO BRAIN/PCH.

I would like to start at PP0V75_S0_DDRVTT because U7300 is clean but PIN 3 is 0v (PP0V75_S0_DDRVTT) , but
PPVTTDDR_S3 is 0,75V

Last edited by marce002; 09-22-2021 at 05:43 PM..
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Old 09-22-2021, 06:51 PM   #2
marce002
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Default Re: a1286 Dead CPU ? No PPVCORE / No PP0V75_S0_DDRVTT

forgot to mention that GPU was disabled through jumpers, so not gpu at all in this board... previous owner was using fine with no gpu
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Old 09-23-2021, 10:21 AM   #3
marce002
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Default Re: a1286 Dead CPU ? No PPVCORE / No PP0V75_S0_DDRVTT

u7400 is not activating the gates, why? what can i have wrong? (need help troubleshooting u7400), of course R7402 is fine 90.9k and saw all videos related to this.. (larossmann)

Last edited by marce002; 09-23-2021 at 10:25 AM..
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Old 09-23-2021, 05:54 PM   #4
reformatt
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Default Re: a1286 Dead CPU ? No PPVCORE / No PP0V75_S0_DDRVTT

I'd be troubleshooting why PP1V5_S0 is missing first before anything else.
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Old 09-24-2021, 05:12 AM   #5
marce002
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Default Re: a1286 Dead CPU ? No PPVCORE / No PP0V75_S0_DDRVTT

Ok reformatt! now PP1V5_S0 is present i cant determine why was not yesterday. Rest is the same no vcore...and no PP0V75_S0_DDRVTT I just want to understand a method to conclude a bad CPU here in casi that is the issue.... u7400 is not activating gates because load is bad o because is malfunctioning?
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Old 09-24-2021, 10:26 AM   #6
marce002
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Default Re: a1286 Dead CPU ? No PPVCORE / No PP0V75_S0_DDRVTT

ok I can hear the chime... did not much ... just reheated SMC and cpu just a little... activity usb is also present.... im going to test further, who knows.... cpu is often not died.. was consuming 340mah aprox, now stabilized at 650mah aprox, but reached 1A at initial starting up no battery no screen just motherboard and gpu is disabled.
It was giving NO VIDEO despite of its chime, but was because came with U9000 missing, as it is just a mosfet IN-OUT jumpered to test , and it gives normal VIDEO thanks!

Last edited by marce002; 09-24-2021 at 11:17 AM..
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