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The macbook works very slowly and the fans rotate very loudly! I put the board in another case but the problem remained! I tried to restore it through DFU but it didn't help. Resetting the smc and pram doesn't give any results! Diagnostics shows problems with the smc. Please help me solve the problem.
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SMC communicates using the SMBUS interface. Measure the voltage to ground on each and every SMBUS line (SCL / SDA) to see if any of them are stuck. You may have to flux and reflow the SMC to fix up any dirty contacts but first review the SMBUS lines. -
I checked the whole board and it looks perfect, no signs of corrosion, SMBUS_3V3_BATT_SCL and
SMBUS_3V3_BATT_SDA = 3.3v
! Tell me where is the smс?Comment
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the problem was in the bad u5860. replacing it fixed the problem.Comment
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Hey guys,
I got a MacBook Pro a1989 820-00850-A dead for repair. The MacBook itself was off for a month or so and it didn't power on. I tested using ammeter and it was stuck on 5v. Opened the machine and found a short on ppbus_g3h, corrosion near the right spkr_amp. removed the spkr_amp and saw short on ppbus_g3h. plugged in to power, boosted to 20v .600A and then back down to .300A. Trackpad was clicking when on .600A but no image etc.
Later, I tried again but it dropped down to 5v and never boosted back to 20V. checked board again and found ppbus_g3h shorted again....10-06-2025, 08:45 AM -
Hey everyone!
I have a MacBook Pro A1989 with a 820-00850-A board that recently stopped working. I used it overnight to charge my phone, in the morning it didn't turn on, I assumed flat battery but now won't charge and doesn't start at all.
I have fully dissassembled it, when disconnected the battery reads at 0.012V. Even with the battery disconnected the laptop doesn't boot.
The diode voltages around all 4 CD3215's seem fine.
For all CD3215 (UB300, UB400, U3100 and U3200) I read just above 5V on PP20V_USBC_TA_VBUS, 3.3V on PP3V3UPC_TA_LDO, 1.8V... -
Hi everyone,
I have a MacBook Pro A1989 that was likely exposed to liquid. It doesn't display an image on the built-in screen, but the screen is backlit (you can't see the Apple logo or any other elements when held up to light). The laptop provides 20V and 1.5-2A, and it works fine when I use it with an external monitor. Currently, the connector for the display (J8500) is disconnected. I'm writing to ask for help in diagnosing the issue. I've heard that when the J8500 is exposed to liquid, the processor pin responsible for the display might short-circuit, and I'd like to know... -
Hi,
I’m having an issue with an A1989 board after water damage, it’s stuck at 5V 0.20A. I’ve checked the measurements, and all readings are the same across all four CD3215 chips. I replaced them one by one (using chips from a donor board), but nothing has changed.
I don’t need a fully functional board, as the repair is only for data recovery purposes.- PP3V3_G3H: 3.3V
- PPBUS_G3H: 12.26V
- PP20V_USBC_XB_VBUS 5V
- PP3V3_UPC_XB_LDO 3.3v
- PP1V8_UPC_XB_LDOA 1.8V
- PP1V8_UPC_XB_LDOD 1.8V
- PP1V1_UPC_XB_LDO_BMC 1.1V
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Today I have a MacBook A1989 at work 820-00850. When assembled, the laptop switches to 20 volts but the consumption is 0.00 ampere. if the motherboard is on the table then the consumption of all ports is 5 volts and0.35 amperes and does not go to 20 volts only if you assemble a MacBook.
Here are some measurements, maybe someone can tell what the problem is.
The initial problem was a burnt out induction coil L8504 (replaced).
When connected to another MacBook, it constantly hangs in dfu and cannot install updates, something is wrong.
here are some measurements
motherboard...
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