MacBook A2289 820-01987

[Zparts01]

Hi mon2! The voltage on the usb C meter is 20v and 0.01a, then climes to 0.11a for a sec, then loops back to 0.01a. The reading is the same for both usb C ports on both sides. I am using the 61W USB-C Power Adapter and cable that came with the MacBook, but I have also tried another 96w Apple Charger as well with the same results. Also, might be worth nothing that it's the exact same readings even if the battery is connected or not.

[mon2]

Check the resistance to ground of each inductor onboard. Searching for any improper loads on the rail. A low resistance reading is a suspect.

Check resistance to ground on PP2v5_NAND_SSD_0.

[Zparts01]

Thanks mon2 I will have to check it and get back to you!

[Zparts01]

Resistance to ground on PP2v5_NAND_SSD_0 is .427

[mon2]

That is a diode mode voltage reading which looks ok.

Meter in lowest resistance scale. Then measure the resistance to ground of this same voltage rail in ohms.

[Zparts01]

31.32 ohms.

[Zparts01]

That's with red on ground and black on component. Other way around it starts at 11.1 and starts to drop.

[Zparts01]

Does that number look correct?

[Zparts01]

Anyone?

[Stephen]

Source a good known battery like mon2 stated. Whoever said you don’t need a battery to DFU is some what correct and incorrect. But most likely you will need a good known battery to DFU correctly. Try that first then proceed further

[Zparts01]

Thanks Stephen, but you may have missed that I have already tried a brand new known working battery. That was not the issue. I was trying to find out what the resistance to ground on PP2v5_NAND_SSD_0 should be.

[Zparts01]

I guess no one has any idea's what I might try next?

[mon2]

What is the voltage to ground of the following?

I2C_PWR_SDA_R2
I2C_PWR_SCL_R2

I2C_THMSNS_SCL_R0
I2C_THMSNS_SDA_R0

I2C_SENSE_SCL
I2C_SENSE_SDA

[Zparts01]

Hi mon2! Thanks for your reply. The readings for I2C_PWR_SDA_R2 and I2C_PWR_SCL_R2 are looping from 0v - 1.8v over and over again. The other areas you mentioned have zero voltage.

I2C_THMSNS_SCL_R0 = 0v
I2C_THMSNS_SDA_R0 = 0v

I2C_SENSE_SCL = 0v
I2C_SENSE_SDA = 0v

[mon2]

For each of these i2c lines that are at 0 volts, check them in diode mode.

Remove all power, meter in diode mode. Red meter probe to ground. Black meter probe to point to test.

Post each diode mode measurement.

[Zparts01]

Thanks mon2! I will do this for sure and post the readings once I have them. I'm off for a week so can't get at it right now! Cheers!

[Zparts01]

Hi mon2! The readings are ...

I2C_THMSNS_SCL_R0 = 0.489
I2C_THMSNS_SDA_R0 = 0.488

I2C_SENSE_SCL = 0.519
I2C_SENSE_SDA = 0.519

[mon2]

These are good diode mode readings. With the posted values, these lines are not shorted.

What are the voltage readings to ground for the following points?

SMBUS_3V3_BATT_SCL ; expecting each to be @ 3v3 but confirm
SMBUS_3V3_BATT_SDA

See attached. Check the voltage to ground of PP1V8_G3S. What is the measurement?

[Zparts01]

The readings are ...

SMBUS_3V3_BATT_SCL ; Cycling back and forth between 3v3 and 2.75
SMBUS_3V3_BATT_SDA ; Cycling back and forth between 3v3 and 2.75

Zero voltage to ground on PP1V8_G3S

[Zparts01]

Does that give you any idea what it could be?