First Board Repair 820-2936 - quater fan spin.

[2informaticos]

First of all, welcome to the forum!

Do not bother more with U7000, as you have correct PPBUS_G3H voltage.

"PPVCCSA_S0_CPU - Dead "
This is a problem, if you don't get pulse at least, like in other points.
It is required before VCORE appears.
Check diode mode to ground at L7100 and some voltages at U7100; pins 7, 15, 19, 20.
Try to catch any pulse, if possible...

 

[2informaticos]

Surelly no pulse at all at VCORE?
Check R7402 ohm value.

 

[DataQueue]

This is the screen, a trophy in my work space.

 

[2informaticos]

Test the board aione on the desk; nothing connected, apart of Magsafe and fan.
Check fot pulse at coils; pages 67, 70/71.
Also check for pulse all the power rails at pages 71/72.
Check for short, where no pulse detected.

Did you try to start in SMC bypass mode?

Inspect all SPI Bus Series Termination resistors and their traces.
Try known good BIOS too...

 

[DataQueue]

Hi,

Yeah it was already out. I'll do all of this tonight.

I'll have to google the SMC bypass mode etc whilst I am at it. I am new to Macbooks.

Thanks again. for all your help.

 

[DataQueue]

Hi , not finished yet, just keeping a log.

If I am reading right the output voltages from page 71
PP1v8_S0 - pulses
PP1V2_S3_ENET_INTREG - pulses
PP1V05_SUS - a nice and good 1.06v steady
PP1V05_S0_PCH_VCCSADPLL - pulses
PP1V5_S0 - Pulses

From Page 72
PP3V3_S4 - solid 3.33v
PP3V3_S3 - pulses
PP1V5_S3RS0 - pulses
PP3V3_S0 - a bit sus, it wiggles and pulses a bit but not high. I either can't get a reading on it at multiple points... OR..... something is wrong. not pulsing very high at all (90mv), and showing Open Line briefly.
I went to q7830/c7830 same result. I am getting 10k at c7830 for PP3V3_S0
PP3V3_SUS - 3.3v
PP5V_SUS - 5.00v

At this point going to call it a night as it's late. Will pick it up tomorrow and continue. Am I onto something with PP3V3_S0? Feel like such a noob with this stuff.