820-2915-B Chime, Boot to OS, Hear sounds, but No Video

[MasterChief2]

Hello to all. This is my first thread, and I hope someone will help me with this board. I would like to say that I'm new to logic board repairs, but I know how to measure voltage, resistance, know what is diode mode and things like that. Let's start.

I have MacBook Pro 15" 2011 without VIDEO. So it's not problem with backlight because I dont have video signal at all. PPVCORE_GPU is 0V, and it should be as I understand 1.10V when laptop is off, and 0.9V when GPU is initializied. I know it's not problem with GPU because MacBook chimes, boots to OS X, keyboard backlight is working and I can change brightness of keyboard, and also I can hear sound when pressing volume up/down on keyboard. So problem is definitely with PPVCORE_GPU.

So as I said earlier PPVCORE_GPU is 0V, PPVCORE_GPU_REG_R is also 0V. Watching on schematic I'm thinking problem may be with U8900 or GPU VCORE Regulator (if I'm right?) Also I suspect on Q8950 or Q8951 but I dont know how to check them with multimeter, and also I dont understand how can I check does this two MOSFETS are getting signals on GATE from U8900 regulator?

I would apprecieted any help on this. Thanks in advance!

[piernov]

Re: 820-2915-B Chime, Boot to OS, Hear sounds, but No Video

820-2915 will of course have a dead GPU in any case.

[MasterChief2]

Re: 820-2915-B Chime, Boot to OS, Hear sounds, but No Video

I don't think GPU is bad because it's booting to OS X. And if it's bad I would disable it and use it with only integrated graphics. I also tried to disable GPU and use only Intel but than backlight doesnt work. So there is definitely some other problems. If anyone have any ideas, please say. Thanks!

[piernov]

Re: 820-2915-B Chime, Boot to OS, Hear sounds, but No Video

Dead dGPU doesn't necessarily prevent from booting into macOS. Sometimes yes, sometimes no.
If you have image but not backlight when forcing iGPU, then at least the issue with dGPU has been taken care of.
At least with High Sierra, you have to pull the backlight PWM signal to 3.3V.

[MasterChief2]

Re: 820-2915-B Chime, Boot to OS, Hear sounds, but No Video

Thanks. I managed to disable AMD GPU on blind, and now it's works only with iGPU. Problam was probably with GPUVCORE chip regulator or with GPU.

[dellxps15]

Re: 820-2915-B Chime, Boot to OS, Hear sounds, but No Video

today i replaced the gpu bga with a new one from goldenchipset. whole process was fine. gpu soldered ok after 20 min to allign it without markers onboard, but now i have black screen when powering on the macbook. i ear chime and so on, but no video, and on C8943 i have 1.1 1-13 volt but on a working one it goes to 0.9 when monitor turn on, so something is wrong with the gpu, but gpu should be a good one since it was looking in perfect new condition. original gpu was 2015 ( maybe a refurbished board from apple) and the new one is 2017.

[piernov]

Re: 820-2915-B Chime, Boot to OS, Hear sounds, but No Video

goldenchipset is known for selling garbage GPUs, especially for this series. Finding good new GPUs for MBP 2011 is very hard. see-ic may have some good ones but they also send garbage sometimes.
Could always be an issue during soldering though.

[MasterChief2]

Re: 820-2915-B Chime, Boot to OS, Hear sounds, but No Video

today i replaced the gpu bga with a new one from goldenchipset. whole process was fine. gpu soldered ok after 20 min to allign it without markers onboard, but now i have black screen when powering on the macbook. i ear chime and so on, but no video, and on C8943 i have 1.1 1-13 volt but on a working one it goes to 0.9 when monitor turn on, so something is wrong with the gpu, but gpu should be a good one since it was looking in perfect new condition. original gpu was 2015 ( maybe a refurbished board from apple) and the new one is 2017.

When GPU is powered on, PPVCORE_GPU should drop from 1.1V to 0.9V. That is probably bad GPU.

[dellxps15]

Re: 820-2915-B Chime, Boot to OS, Hear sounds, but No Video

yes i have measured that on a booting board. now i have another bga, same model same datacode as i ordered 2 from goldenchipset. the first one got reballed with leaded balls ands soldered on it without backing the bga.

now i dunno if try the other chip on a second board, solder it with its original lead free balls or reball it, or try that chip on the first non booting board to see if it was really the bga itself . in both case this time im gonna backing the board at 98° celsius for 4-6 hours before solder the chip in it.

i attached picture. on the old soldered 2015 bga u can see solder on top 4 pins, while on 2017 bga from gc u can see those 4 pads have no solder, like 100% new...

i also used a permanent marker before remove old gpu, but when i was desoldering it, flux make the marker liquid and useless

[tata123]

Re: 820-2915-B Chime, Boot to OS, Hear sounds, but No Video

yes i have measured that on a booting board. now i have another bga, same model same datacode as i ordered 2 from goldenchipset. the first one got reballed with leaded balls ands soldered on it without backing the bga.

now i dunno if try the other chip on a second board, solder it with its original lead free balls or reball it, or try that chip on the first non booting board to see if it was really the bga itself . in both case this time im gonna backing the board at 98° celsius for 4-6 hours before solder the chip in it.

i attached picture. on the old soldered 2015 bga u can see solder on top 4 pins, while on 2017 bga from gc u can see those 4 pads have no solder, like 100% new...

i also used a permanent marker before remove old gpu, but when i was desoldering it, flux make the marker liquid and useless

Hey nice idee with the marker, but i think this is not necessary because you cant do much failure putting the chip back to the board, if you have good BGA Flux!!

These Chips are all garbage, its a shame from ATI, because in my eyes these Macs are damn good, if they wont have these shitty ATI Chips...