2015 a1502 820-4924 ASD ERROR PFF004 "there may be an issue with the fan"

[roy.ruan]

hi guys,
having a a1502 board, 820-4924.

machine can't boot into any OS, kind of like the sensing circuit issue slow.
option+D to run ASD and had a result PFF004"there may be an issue with the fan"

I replaced the fan and have the same result.
thought can be the issue with the fan circuit,so replaced Q6060 , and check resistors values on R6061 R6065 R6060,all match the values on schematics.

dont see any spills around the board, doubting if its' a bad SMC now?

any suggestion please?

thank you!

 

[dukefawks]

Was the ROM chip touched?

 

[roy.ruan]

yes of course, the machine can power on ,posts without problems,you can hear chime, see logo, then loading and stuck there.

 

[dukefawks]

I dont understand the answer to my question. Yes of course the ROM was messed with?

 

[roy.ruan]

I meant the rom was there and never touched. looks very fine to me

 

[roy.ruan]

sorry about the confusion,thought you said if it was installed

 

[dukefawks]

Is the fan spinning up during the hardware test? Is there liquid damage?

 

[roy.ruan]

it doesn't spin all the time, but when the test goes like 60% , it spins full speed then slow down later on.
don't see any liquid damage,checked couple times already.

 

[dukefawks]

So it it is able to control the fan. So probably it is not seeing the tacho signal.

Again, was there liquid?? Is it power on from the battery?

 

[roy.ruan]

i double check couple times already. all those cycle water testing stickers are all white,not red.
and don't see any red point and corrosion as well. and yes, it does power on from the battery.

 

[dukefawks]

Honestly I have no idea what is wrong. A bad fan would not cause it to not boot an OS. This is one of those machines that you need to take to an AASP and have them run AST/MRI on and see which sensor(s) are failing. Apple sucks for not providing stand alone ASD anymore, RIGHT TO REPAIR!

 

[roy.ruan]

Exactly!! if we have ASD for this model, way much easier and big chance it can be fixed.
and yes, right to repair man!! THEY SUCK, wanna monopolize the after sale repair, and make the most profit out of people who buy their products.

but people who have the skills should have the right to do it! we should have those info,just like the schematics, I don't mind even paying at a reasonable price.

anyway, I don't think AASP can be an option for me, last step i would take probably will be the SMC, what do you think about that?

 

[dukefawks]

I doubt the SMC is the issue, it does not just die. I really have no idea on this besides that you need to run AST on it. Randomly replacing stuff will only make things worse.

 

[roy.ruan]

alright got you man. thanks anyway!