Wifi problem MacBook Pro unibody mid 2012

[davg]

I need help with a MacBook Pro mid 2015 with liquid damage. I cleaned the board and put in back in and started it up but it would only go so far into the boot than shut down? I than disconnected all components and reconnected them one by one and found that the wifi cable was the problem, boot so far and shut down. disconnect the wifi cable and it will boot no problem?? Ethernet works fine. Wifi and Bluetooth is on the same cable. Has anyone experienced this problem? any ideas where to look for a salutation?

[polytek]

Re: Wifi problem MacBook Pro unibody mid 2012

please post the motherboard code

[davg]

Re: Wifi problem MacBook Pro unibody mid 2012

please post the motherboard code

Thanks for your reply it is a 820-3115-B

[polytek]

Re: Wifi problem MacBook Pro unibody mid 2012

see page 32 air port
check the coil if shorted to gnd, check the power PP3V3_S3_WLAN if exist
check Q3550 if shorted

[davg]

Re: Wifi problem MacBook Pro unibody mid 2012

see page 32 air port
check the coil if shorted to gnd, check the power PP3V3_S3_WLAN if exist
check Q3550 if shorted

Thanks again. and please excuse my limited knowledge in some of these areas but Just to be sure when you say coil are we talking L3504? I'am away for a couple of days and unable to take these measurements till I get back.

[polytek]

Re: Wifi problem MacBook Pro unibody mid 2012

Thanks again. and please excuse my limited knowledge in some of these areas but Just to be sure when you say coil are we talking L3504? I'am away for a couple of days and unable to take these measurements till I get back.

check the 4 coil on the picture attached:
l3504, l3505, l3506,l3501

[davg]

Re: Wifi problem MacBook Pro unibody mid 2012

check the 4 coil on the picture attached:
l3504, l3505, l3506,l3501

Thanks will report back after the weekend.

[davg]

Re: Wifi problem MacBook Pro unibody mid 2012

Thanks polytek I am getting 3.3volts on pin 1 c3550,c3521 c3520 & pin 1&2 l3504
I am not sure how to check q3550 to gnd? Q3550 on the board has 6 contacts and the schematic and bview it is showing only 4 contacts?

[polytek]

Re: Wifi problem MacBook Pro unibody mid 2012

post you schematic and bdv and logic board code;

[polytek]

Re: Wifi problem MacBook Pro unibody mid 2012

please , post your schematic and bdv and logic board code;

[davg]

Re: Wifi problem MacBook Pro unibody mid 2012

please , post your schematic and bdv and logic board code;

The logic board is a 820-3115-B (HF/e1) the schematic and boardview is the attachment from post 4

[polytek]

Re: Wifi problem MacBook Pro unibody mid 2012

can you post a photo of the mosfet on the board,
here the datasheet of the mosfet you need to check D-S; G-S,G-D for short or low resistance.

[davg]

Re: Wifi problem MacBook Pro unibody mid 2012

can you post a photo of the mosfet on the board,
here the datasheet of the mosfet you need to check D-S; G-S,G-D for short or low resistance.

Thanks the data sheet makes more sense. with diode mode
bk on pin 1 (S)
rd on pin 3 (G) no reading

bk on pin 1
rd on pin 4,5,6 (D) no reading

rd pin 1
bk pin 3 no reading

rd pin 1
bk 456 no reading

bk on 3
rd on 456 no reading
Sorry have no means of taking a picture of the board

[n0by1]

Re: Wifi problem MacBook Pro unibody mid 2012

Hello everybody. I have the same problem.
820-3115-b
Wai-fi changed.
The hub changed.
The train was changing.
Tell me = (
And forgive my English. I'm with Russia =)

[avlcat]

Re: Wifi problem MacBook Pro unibody mid 2012

Yet another 3115 board with the same problem. Did anyone fix this?

My board had L3508 (camera 5V coil) burned which caused a bit of burn damage to the board surface. I cleaned the damage and replaced the coil. The board boots now and camera is working fine.

However it only boots fine if wifi cable is disconnected. When cable is connected it boots but shuts down on the Mac OS login screen. If I try to boot from USB (holding Option key after post) it shuts down too; I guess because it activates wifi card immediately.

EFI ASD does not find any issues (I can only run ASD if wifi board disconnected, so it did not test airport board). Same with OS ASD - no issues, but wifi/BT not tested as it had to be disconnected.

One thing I noticed is that when it shuts down, the green light on MagSafe starts blinking and there is a "ticking" sound coming from the board, like tick-tick-tick...

Last observation - if I connect wifi card but disconnect all four wifi/bluetooth antenna wires, it may even boot into OS and not shut down. I am not sure how stable it will be in that condtion though.

Once I removed L3504 (wifi 3.3V power) it will also boot fine; obviously WiFi would not work here but at least it does not shut down.

It all looks like overloading on 3V3 rail, but I cannot find what causes it. The resistance to ground / diode mode on 3V3 rails:

- PP3V3_S5: 200K / 0.152
- PP3V3_S4: 0.384 in diode mode (cannot measure RTG as it fluctuates because of lot of capacitors)
- PP3V3_S3: 6K / 0.356
- PP3V3_S0: 4K / 0.354

Unfortunately I don't have known good 3115 board now so I can't compare the values.

Appreciate any hint or help.

[avlcat]

Re: Wifi problem MacBook Pro unibody mid 2012

Finally found and fixed. It was bad U7200 (TPS51125).

[kingskie]

Re: Wifi problem MacBook Pro unibody mid 2012

Finally found and fixed. It was bad U7200 (TPS51125).

this one work for me for wifi..but the camera stil not detected. thanks @alvcat