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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 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... -
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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Hello everyone.
I have recently obtained a MacBook Pro A1989 model with a touch bar and Apple ID. Unfortunately, it does not want to start up.
No CPU Voltage.
U7800 Does produce voltages.
T2 Chip warming up very very little.
I do have voltages like 1.8, 0.9, 3.3, 2.5 volts, etc., present. I did not find any short circuits. Unfortunately, the device has no touch ID/start button. So, I have used the debug jumper to put the device into DFU mode. - It is getting recognized as a Macintosh while not in DFU mode and as Apple (DFU) while in DFU mode....11-24-2023, 11:55 PM -
Hi guys.
I Just replaced battery on my MacBook Pro A1989. Unfortunately doing that, I’ve broken the trackpad flex cable (821-01701-a), and I’ve already ordered a spare one. At the same moment I’ve noticed that also the keyboard it’s not working anymore and I’ve found an SMD chip unsoldered and moving freely inside the backplate. I can read L20L on the chip. Is something could explain the keyboard not working or the keyboard doesn’t work due the unconnected trackpad?
thanks...04-17-2025, 09:42 AM
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