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820-3662-A - No Chime, No Screen

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fredddd

New member
Hi all, I have an 820-3662-A board from a 2013 Macbook Pro Retina. It has a light on the charger and fan spin, however I get no chime and no image or backlight on the screen. The board was water damaged but there is very little corrosion, most of it on the I/O board. I have tested the 5V, 3V and 1V power rails listed on the power aliases page of the schematic, all of which are fine. I have 1.76v for CPU VCore and the CPU warms up as would be expected.

Out of respect for the forum, I will be honest and admit that I am new to component level repair. I don't have a huge amount of experience but I'm here to learn, not just free load off the experts who reside here! Any help would be much appreciated!
 
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fredddd

New member
A glass of water was spilled over the keyboard whilst the computer was open apparently. I've tested with just the screen nothing else, screen and keyboard and then screen with everything plugged in.
 
J

JohnB8812

New member
Ok next step would be to check if you get USB activity on a USB mouse/pen drive. If yes, image is the issue. If no, either corrosion somewhere, bad BIOS, bad CPU, corrosion by/bad SMC etc and this will suck.
 
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fredddd

New member
Yeah sounds like it! As far as troubleshooting goes, have I got any options for getting closer to the problem or is it just a case of trial and error?

EDIT - Sorry, this was a really poorly worded question. I don't know where to start looking, could you suggest a starting point that I can look into? I don't really want to go down the classic newbie route of "replace it until you fix it".
 
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J

JohnB8812

New member
Inspect the board very closely for any hints of corrosion. There has to be SOMETHING if this was water damaged....if nothing is found this is a time waster....
 
2informaticos

2informaticos

Administrator
Staff member
Disconnect any peripheral, like TP/KB, camera, LCD, etc.
Keep only DCIN board and connect USB mouse on the MLB port; disconnect RIO board completely.
Better to use an USB pendrive/HDD with Link LED.
If no USB activity, very likely bad CPU.

Power supply of this board is a nightmare.
F***g FDMF6808N chips kill the CPU most of the time; even without apparent reason...
 
F

fredddd

New member
I disconnected everything, leaving just the fans and tried a usb drive. Still nothing!
Am I looking at replacing the whole board to get this thing working? Do people replace CPUs in Mac boards or is it generally a lost cause at that point?
 
2informaticos

2informaticos

Administrator
Staff member
If you really have time to waste, checnge all (3) FDMF6808 with new FDMF6708 from Mouser, not from China.
I doubt this will help in this case, as no previous issue reported about randomly freeze, or shutdown.
 
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