MacBook Pro Retina Late 2013 shows light, fan spin but no chime

[Gigabit2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

Hi mon2,



Here is chip you said for reflow. Do I remove this rubber stuff or I can just go straight with hot air?

[mon2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

Yes - with hot air - this stuff becomes brittle and you can gently scrape it away. That is what we have found. It is much like a glue and also will give out a bit of an odor so have a ventilation fan running to avoid the fumes.

Just do not scrape away any PCB parts.

Reference (same fault - different board - same part):

https://www.youtube.com/watch?v=BYLuJBNLHSU

[mon2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

WAIT !! Why do you have underfill and is a BGA device ?

What are the markings on your IC ?

[Gigabit2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

Oh I did it now anyway

[mon2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

Ok - no worries if you have made it dance with flux - no harm but what are the markings on the IC ?

Let me check my schematic again.

[mon2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

On logic board # 820-3787-A; U9300 = QFN package like Louis is showing in his video but he is fixing a different A1398 logic board with the same fault.

Your U9300 = BGA ??

never mind - false alarm - the picture is blurry from my side - it is a QFN but still with underfill. interesting.

Proceed - this single device is a root cause and is mentioned on numerous forum chats.

without this buck regulator; the GPU is no longer powered !

[Gigabit2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

I did it, laptop now stays on and fan spins full speed like jet engine. But no chime or screen.

[Gigabit2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

No was false alarm, system still turning off

[Gigabit2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

No was another false alarm sorry. System IS staying on and fan spinning at max speed but no chime or screen

[mon2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

Interesting. Can you confirm the GPU voltage rail created by this IC ? What is the voltage?

[Gigabit2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

Can you tell me what to check precisely?

[mon2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

Voltage @ L9330, pin # 2 = PPVCORE_S0_GFX_REG

[Gigabit2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

00.0 on 200m mode

[mon2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

Locate and reflow the following 'thermal sensors' for the GPU.

Flux and reflow each. Test again.

Need to make a Costco run..will check back later.

reference:
https://www.youtube.com/watch?v=o94idr9SW-w

[mon2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

00.0 on 200m mode

hmm.. not like Louis' video. Check the thermal sensor post above.

[mon2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

Each of the GPU mosfets must be inspected for shorts using RESISTANCE mode checks.

Note that some of these mosfets are 2 inside a single package. Remove all power -> check the mosfet resistance readings.

Will review later..

PS: Watch the video from Louis - he references these mosfets and they also die often but may also kill the GPU..TBD.

[Gigabit2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

GPUVCORE_PGOOD showing as .027 on 2V mode, ok reading?

[Gigabit2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

FYI here is the area around U9300 under the microscope:

[mon2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

Hi. See attached.

See many parts surrounding the GPU buck convertor that have been displaced.

It is vital to review the boardview files -> locate this IC -> locate each and every part around the perimeter of this component and carefully correct their placements. Without the correction, the board does not stand a chance to function properly.

Have highlighted what I believe are parts that must have been moved by the reflow process. There may be others. This is just a cursory review.

Ok to use high heat but lower the air pressure so that the parts do not fly away.

[Gigabit2]

Re: MacBook Pro Retina Late 2013 shows light, fan spin but no chime

Hi mon2,

Yes I will correct it. How does IC look to you? With reflow it came off so I put it back on.

What heat are you advising, was using up to 450 to get IC off with Quick station