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I figured that be it too but i noticed on other machines when its a bios issue the machine will do quarter fan spins not constantly fan spin. I will try replacing tho.

The macbook turns on cpu heats up and fan spins but no chime no image nothing on external monitor. I use a backlit keyboard to test machines to see if theyre at least booting on these ocassions but it doesnt even light up. My guess is that its brain dead but cpu is present at 1.8v so not sure...

Macbook had water damage retraced some areas reflowed smc and got it working but had no backlight. After working in backlight for a bit i realized the machine stopped posting. ppvcore cpu is 1.1v not sure what happened but last thing i did was replace the led driver thats when it stopped...

Ran board through ultra sonic and replaced some suspicious resistors and retraced line but still no luck. Any other ideas?

Switched out u6620 changed u6201 checked traces for c6620/21 and r6622 even changed out c6620/21. Still no luck but i did notice that u6880 and sorrounding resistors had water damage as well.

Yes tried another and even tried a known good board and it gives out a chime

l6620/21 start at 2.5ohm and drop pram has been done multiple times.

already tried a known good speaker and i get no sound from it. no chime. j6703 does get voltages under 1v each pin gets. but on a known good board those pins get no voltage at all tried swapping out u6620 and u6610 no luck. machine produces sound from the small speaker but not sub

ok well i had the max voltage too high o-scope showing 3.60v on those pins now. when i trigger smc_onoff_l i get a pulse but voltage stays the same. i do see a slight fluctuation of 3.60v to 3.80v on u6100. does this mean the pch is not reading the bios then?

pin 2,5 and 6 do show activity o-scope says 36v seems odd but multimeter shows 3.3v on those pins rest of the pins are 3.3v according to multimeter except pin 4 of course

i get pulses on l7520 and PM_SLP_S3_L and checked other coils before i got pulses on all of them except the backlight coil

figured out the oscope a bit and going back to the question "PM_SLP_S5/4_L no reaction at R5115/16? Use an o-scope to catch any rapid pulse there..." i do get rapid pulse on PM_SLP_S5/S4_L Not sure if that helps any tho..

Just got a rigol Ds1102e have no idea how to use it or what to look for but maybe you can give me some type of guidance on what to look for to hopefully get this going?

Changed some caps still same issue im just gonna move on.

Before measuring i had replaced y2805 and associated caps i guess maybe 3rd times the charm?

Y2805 pin 1 - pulses up to 0.014v pin 3 - fluctuates from 0.328v to 0.700v u2800 pin 1 - 3.3v pin 2 - 3.3v pin 3 - pulses up to 0.023v pin 4 - fluctuates 0.647v to 0.743v pin 5 - pulses 1v pin 6 - 1v pin 8 -0.065v and drops to 0.055v pin 9 - 0v pin 11 - pulses 1.7v pin 12 - 0.396v pin 13 -...

Traces are good even replaced again and nothing

I changed both those and still same issue ill try n change it one more time

All coild except the vcore ones pulse. L7520, L7510, L7550 dont pulse. R7402 is fine ALL_SYS_PWRGD pulses Cant check with an o-scope but i get a straight 0v no pulsing on SYSCLK_CLK25M_SB

checked all spi termination reistors and traces all is good even reprogrammed bios with no luck. board had prior water damage it did at one point keep fan spinning but got no cpu checked the cpu ton resistors for u7400 even replaced u7400 still no luck and board is back to quarter fan spinning...