[help] 820-00840 “seems to boot”

[phantom]

i'm pretty sure that usb ports were changed....so i would like to check in diode mode each pin of both usb soldered on the mothgerboard...but i have not other motherboard to compare

 

[phantom]

Sorry, my mistake about Medusa.

I will try to clean your dump later.

Could you help me please?

 

[richilg1]

Was the bios issue resolved, does it boot to recovery again, or still no startup sound? If it boots and you're having port issues, check that all the pins are seated well, if someone changed the USB ports. Also, you could remove or replace thunderbolt controller (U2800). That chip can cause issues if it's bad, and it can be absent to use the computer normally. Also, are you trying known good SSDs? SSD failure will cause hangs in recovery or OS, or won't show. When you tried a new SSD, did it have an OS or was it blank?

 

[2informaticos]

Sorry for delay, I was 2 days in hospital.

Did you try PRAM reset?
Also test starting in safe mode.

Starting in diagnostic mode, brings any information?

 

[phantom]

2informaticos, how are you?? all ok?

i try to summarise

i have activy led for both usb

i can't boot any os from both usb

ssd not seen (even with another ssd)

if i go in recovery, as soon as i insert wifi passord, mac hangs and reboot

ic camera was 100% resoldered (i don't know why)

usb ports were 100% resoldered (i don't know why)

i'm pretty sure that cd3215 were changed (they have different serials)


i think i can't boot in safe mode because ssd is not seen


i'm pretty sure that usb and ssd not seen is the same problem

u8640 not present...i don't know if it is normal...

i've another identical motherboard and it hasn't u8640 too

 

[2informaticos]

If R8641/2 are soldered, then no need to use U8640.

This board is probably time wasting; you can't be sure what components have been removed by previous workshop.
Missing one resisotr, or cap, can make the board trash.

You can try known good BIOS, just in case.

 

[phantom]

Bios already Tried…you gave me it some days before…

 

[phantom]

edit

 

[phantom]

so i have bought a fully working motherboard..

all ok except sound...i can't hear sound from speakers!

i can hear sounds from headphone...

no problems found in diagnostic mode

in settings, i can see "internal speaker" like output..

tried smc reset no luck

 

[2informaticos]

You may have problems with audio flex, or small audio board; where the audio jack is placed.

 

[phantom]

What do you mean with AUDIO FLEX??? Or small audio board????? It is a MacBook Pro….

 

[2informaticos]

It connects to J6600...

 

[phantom]

with the old board i have audio...

 

[phantom]

I have sound from headphones… I can set volume from button, but no audio from speakers…how is it possible? I’m going crazy!!!!

 

[2informaticos]

So you've located the problem on the MLB for sure.

Check diode mode readings around audio amplifiers.
You may need to change them all.

 

[phantom]

Diode mode for shorts?
Could you show me where are the audio amplifiers? Are the 4 chip on the other side of the motherboard?

 

[2informaticos]

The chips from page 50.

Probably no short, but compare readings with other board.

 

[phantom]

solved changing 2 amplifiers