820-01987-A Macbook Pro A2289

[jimanez11]

Have a Macbook Pro A2289 that I bought off of ebay with cited "Juice Damage". The damage didnt look too bad on the site, and honestly doesnt look that bad in actuality. But alas, it is indeed fairly bad (at least to my incredibly limited knowledge). Armed with a silk-screen image of the board layout, multi meter, schematic, and a very limited understanding of how logic boards function, I remain (unsurprisingly) vexed by the situation. The current status of the machine is as follows:

- USB C volt tester indicates the board is pulling a steady 20.1v

• amperage bounces up to sometimes 400mA, sometimes 380mA for a split second before going to 0, then back up to around 200mA, and then staying at a constant 20mA until restarted.

- PPBUS_G3H is a steady 12.61 throughout the board
- PP3V3_G3H is steady 3.3 throughout the board
- PPVCC_S0_CPU is .84v for about 10 or so seconds (until the board only takes .2amps) and then drops (measured on both L7210 and L7220)
- PPVCCGT_S0_CPU is completely non-existent when measured on L7410 and L7420 (which made me trace this back to U7400)
- U7400 is getting required 5v on VCC and 12.61v (from PPBUS_HS_CPU).

Then I traced this back to U7100 and pulled the following from the test pads:
- CPUCORE_PWM1 (PP7100) - quick flash to 2.3v when power applied, then to around .6v for a few seconds before dropping and holding at .038v
- CPUSA_PWM (PP7102) - gets up to .47v and then switches to low
- CPUGT_PWM2 (PP7104) 2.55v for 10 seconds, then low
- CPUGT_PWM1 (PP7103) 2.55v for 10 seconds, then low

It looks like there is some gunk under Q7660 and under C8412 has a solder tail, so it may have been replaced? Not sure though.

When everything is hooked up and plugged in:
- power button responds when pressed to power on and held to turn it off
- fan spins for a second or two, then stops
- Keyboard backlight is very dim
- Able to get into DFU Mode with another macbook, so USB is sending / receiving info.
- Trackpad will also click until powered off
- No image or backlight and screen is broken

I reached out to the person I purchased the machine from and he didnt try any repairs, just "scrubbed the juice off with alcohol and a stiff brush". The "stiff brush" part may explain why I found a .01uF capacitor stuck to the adhesive around the trackpad (still no idea where it came from).

Appreciate the advice and any knowledge / guidance / next steps you all are willing to share.

[piernov]

Re: 820-01987-A Macbook Pro A2289

No idea why would you buy a very difficult board to repair when you have not much experience, especially from eBay and with a broken screen (second most expensive part after logic board and extremely difficult to find a good quality one), on top of that it'll probably be iCloud locked…

In any case the board turns on so next step is getting a known good screen.

[jimanez11]

Re: 820-01987-A Macbook Pro A2289

Thanks for the response Piernov - understand that the screen is an expensive part, but got a decent deal on the machine itself. Purchase mechanism and associated decisions aside, its good to know that the board is turning on. I was under the impression that it required 600ma to get to S0, and never saw that come up so wasn't sure. It will likely be a while before a new screen comes in - will post back if any other issues are noted.

[Stephen]

Re: 820-01987-A Macbook Pro A2289

I bought a new oem screen for $315 and worked perfectly. Don’t know if that price is still normal or not today...but careful on the prices.

[jimanez11]

Re: 820-01987-A Macbook Pro A2289

So now have a known good screen and still no image internally or externally. Machine pulls 20v and looks like its booting - gets up to roughly 600ma without battery connected and then goes down and holds steady at ~470 ma. All power rails appear to be turned on and all big coils appear to have the correct voltages. The capslock button does not toggle when pressed and there is still no image. I cant see an LCD enable signal being sent out by the CPU either. Is this a "no brain" case, or would it potentially be a bios issue or something else? Have read a few posts where a reflow of the CPU could possibly remove any gunk from underneath it, but would want that to be a last ditch effort I think. I am able to enter DFU mode and successfully run through the revive process, but there is still no USB activity (led on thumb drive does not blink at all) when plugged in or image on screen afterwards. Any advice on where to go next would be greatly appreciated.

[jimanez11]

Re: 820-01987-A Macbook Pro A2289

Any guidance or next steps, or is there anything else I should be looking at? Am still trying to learn correct methodology for troubleshooting logic board repair, so any guidance is appreciated!