1337GameDev
New member
I currently bought a broken macbook (A2141), that was water damaged, and want to repair it. I have the necessary tools I've amassed over time, but want to begin. I have decent understanding of electronics and the like (I have watched a bunch of videos of repairs, as well as am a professional programmer as my career). I have the board out of the machine, and have organized the screws based on location they came out of and other covers / pieces.
The board has some obvious water damage. I know i'll likely need to source a donor board (i know that can be tricky to source, but i'll worry about that a bit later), but the first part is identifying the damaged components, organizing them / their location on the patient board and ensuring the board doesn't have an "unfixible" component (cpu, ram, ssd, gpu, t2, etc). I have removed the covers on top of these chips, and do not see corrosion near / on these chips. I do not see damage to the LCD connecter, so no 50v should be sent to the cpu / cpu mux. I will likely need to verify this however. I know i'll likely apply conformal coating to this area/other areas for future durability if I fix the board.
My questions are these:
1. What's the first steps to verify the CPU, gpu, ssd, t2, etc aren't going to be damaged if I connect this board to power? I know i should look for obv shorts, but what about verifying that power regulation systems for these won't generate too much voltage? Do I "isolate" these systems by removing caps / chips to ensure any generated voltage won't go to the chips in question and then add back the chips/components once they are checked?
2. What can be done to use a usbc amp-meter to current limit to ensure the board won't short and push a bunch of amps to a valuable chip? I do have a bench current limiting power supply, so i know i can inject voltage and bypass the usage of the amp-meter, just curious on thoughts.
3. On the board view, I tried finding and noting areas of water damage and understanding the circuits impacted, but the board view doesn't line up exactly with the board. I see corrosion around the L7660 area it seems (lower left of the board with the orientation it came out of the machine with the fans up at the top), to the left (close to C6566) on the board view, but there's also a connecter here (my best guess is J6500), that doesn't show up on the board view. So I'm having a hard time identifying components exactly to know if I'm getting a proper ID of components. Is there sub-variants of this board? What are tricks to "orient" or identify components that might be tricky to find on the board vs board view? Are the prefix letters indicative of the component type? (c= capacitor, r = resistor, I = inductor, U = chip, J = connector, etc). I do see an "L" prefix, but not sure what that corresponds to. Ideas / info?
4. What's the best surface to use a hot air station on (well what the motherboard will be sitting on when heating)? I wanted to do this in my living room (and put down a silicon mat to protect the wooden coffee table that states it can handle 400c) and have the fume extractor / camera there. I know not the "best" but i've done work like that before with little issue (i've taken apart hundreds of devices like that). I've heard people say silicon mats, as well as tile, and then things like specializes welder mats or the like.
5. I don't have a sonic cleaner ($1200+ for a basic one). I plan to clean using a toothbrush + alcohol (i know this will take awhile and be annoying / not as good as a sonic clean -- but it's what i have right now). Any ideas / tips / info I need to know when doing this to improve success / durability?
I sourced my board view online, from the "badcaps" forum (has filename of "LB_820-01700_BoardView_file_LO25.brd".) Is this incorrect or for a different variant? The macbook I have is an i7 configured 2019 16inch model ().
Is there any ideas / steps / info I need to know about this board specifically, and is there public collections of diode mode readings to help not needing a donor for comparison (while I look around to source one for a reasonable price)?
Sorry if this info can be googled, I figured i'd ask here to see what info you guys trust and what info you all have to share / help if possible, as there can be conflicting info out there. If you have links you know are good / trust, you can share those too versus just explaining (I understand I'm asking a lot). Thanks for helping! Much appreciated, and hopefully these questions help out others too who are working on their first board.
UPDATE:
On #3, I found a table for schematic prefixes:
L is inductor, and J is a connecter / jack.
I is not used afaik.
The board has some obvious water damage. I know i'll likely need to source a donor board (i know that can be tricky to source, but i'll worry about that a bit later), but the first part is identifying the damaged components, organizing them / their location on the patient board and ensuring the board doesn't have an "unfixible" component (cpu, ram, ssd, gpu, t2, etc). I have removed the covers on top of these chips, and do not see corrosion near / on these chips. I do not see damage to the LCD connecter, so no 50v should be sent to the cpu / cpu mux. I will likely need to verify this however. I know i'll likely apply conformal coating to this area/other areas for future durability if I fix the board.
My questions are these:
1. What's the first steps to verify the CPU, gpu, ssd, t2, etc aren't going to be damaged if I connect this board to power? I know i should look for obv shorts, but what about verifying that power regulation systems for these won't generate too much voltage? Do I "isolate" these systems by removing caps / chips to ensure any generated voltage won't go to the chips in question and then add back the chips/components once they are checked?
2. What can be done to use a usbc amp-meter to current limit to ensure the board won't short and push a bunch of amps to a valuable chip? I do have a bench current limiting power supply, so i know i can inject voltage and bypass the usage of the amp-meter, just curious on thoughts.
3. On the board view, I tried finding and noting areas of water damage and understanding the circuits impacted, but the board view doesn't line up exactly with the board. I see corrosion around the L7660 area it seems (lower left of the board with the orientation it came out of the machine with the fans up at the top), to the left (close to C6566) on the board view, but there's also a connecter here (my best guess is J6500), that doesn't show up on the board view. So I'm having a hard time identifying components exactly to know if I'm getting a proper ID of components. Is there sub-variants of this board? What are tricks to "orient" or identify components that might be tricky to find on the board vs board view? Are the prefix letters indicative of the component type? (c= capacitor, r = resistor, I = inductor, U = chip, J = connector, etc). I do see an "L" prefix, but not sure what that corresponds to. Ideas / info?
4. What's the best surface to use a hot air station on (well what the motherboard will be sitting on when heating)? I wanted to do this in my living room (and put down a silicon mat to protect the wooden coffee table that states it can handle 400c) and have the fume extractor / camera there. I know not the "best" but i've done work like that before with little issue (i've taken apart hundreds of devices like that). I've heard people say silicon mats, as well as tile, and then things like specializes welder mats or the like.
5. I don't have a sonic cleaner ($1200+ for a basic one). I plan to clean using a toothbrush + alcohol (i know this will take awhile and be annoying / not as good as a sonic clean -- but it's what i have right now). Any ideas / tips / info I need to know when doing this to improve success / durability?
I sourced my board view online, from the "badcaps" forum (has filename of "LB_820-01700_BoardView_file_LO25.brd".) Is this incorrect or for a different variant? The macbook I have is an i7 configured 2019 16inch model ().
Is there any ideas / steps / info I need to know about this board specifically, and is there public collections of diode mode readings to help not needing a donor for comparison (while I look around to source one for a reasonable price)?
Sorry if this info can be googled, I figured i'd ask here to see what info you guys trust and what info you all have to share / help if possible, as there can be conflicting info out there. If you have links you know are good / trust, you can share those too versus just explaining (I understand I'm asking a lot). Thanks for helping! Much appreciated, and hopefully these questions help out others too who are working on their first board.
UPDATE:
On #3, I found a table for schematic prefixes:
AutoTRAX PCB Designer > Designs > Projects > Schematics > Standard Reference Designators
A reference designator unambiguously identifies a component in an electrical schematic or on a printed circuit board. The reference designator usually consists of one or two...
dexpcb.com
L is inductor, and J is a connecter / jack.
I is not used afaik.
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