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Update: I finally figured this one out. For haptic feedback and the keyboard to work, the interrupt signal IPD_MCU_INT_CONN_L must be fully functional, in addition to the 4 SPI bus lines. The interrupt signal from the CPU (IPD_MCU_INT_L ) was there, but the level shifter UT340 was not correctly...

Because that's where the original liquid damage occurred, I already replaced all small chips near the connector (level shifters and load switches) from a donor board. So you're saying that at this point nobody understands the trackpad/keyboard/haptic circuitry and bus signals enough to...

I have performed this test many times (for my own sanity), as recently as yesterday. All 3 trackpads I'm using for testing work perfectly fine on a known good A3114 machine: they track, click, and the keyboard works. Flex cable also works fine on good machine.

Regarding the missing keyboard functionality: I have verified that the keyboard bus signals (I2C_KBD_SDA and I2C_KBD_SCL) arrive intact at the trackpad itself (pulses on oscilloscope when I press a key). Something is telling the trackpad to ignore the keyboard data and not integrate them into...

On the good machine the trackpads works fully normally when the daughter board flex cable is removed (no keyboard function, obviously).

Here are my oscilloscope observations of the SPI bus: Known good machine (A3113): CLK line: 32Hz pulses, reacts to tracking, clicking, key press MISO line: 32Hz pulses, reacts to tracking, clicking, key press MOSI line: 3.3V, reacts to clicking, key press CS line: 3.3V, reacts to clicking, key...

Update: when I connected a good battery, the power cycling behavior stopped and all 3 USB ports started working normally. Strange, but the machine is back to working.

After replacing the SPMU (U7100) the machine gets 20V and chimes. However, it is stuck in a boot loop and never fully starts up. DFU Revive fails with error 21 and sometimes 9. DFU Restore fails with unknown error 4042. Am I correct assuming that the NANDs are likely bad and need to be replaced?

I see activity on the I2C_KBD_SDA bus when I press a key on the keyboard. I2C_KBD_SDA data runs through the trackpad, but what is the main data output line from the trackpad? The I2C_SMC_IPD or the SPI_IPD bus?

This 820-02890-A board has seen liquid damage at various locations. I replaced several corroded components (UD600, Q5300, UN400, others) and fixed a short to ground on PP2V5_NAND0. I also replaced one of the CD3217s (UG400) with a location-matched chip from a donor board since it was getting...

Good call. I got an IR camera and found U7100 warmer in one corner by a few degrees °C. Removed it and the low resistance on PP3V8_AON is gone.

After removal of U8100 I noticed that PP3V8_AON is 50Ω to ground. Enough resistance to produce 3.8V but probably not enough to power either PMU. I'm assuming that without a good thermal camera, this short will be impossible to find?

No shorts on the LDO lines. U8100 gets 3.8V inputs but lines like PP1V2_AON_MPM or PP1V8_AON_MPM are 0V.

PP1V5_LDOINT_MPMU is 2.0V. Nothing else.

What's the best way to test the interface busses (I2C_KBD, I2C_SMC_IPD) for full functionality?

The machine has no signs of liquid damage. USB meter shows 5V 0.16A. PPBUS is 12.3V. PP3V8_AON is present. The main PMU (U8100) does not produce any power rails, it appears to be off despite good input power. What signals are required to turn it on?

Any help?

As a workaround, I shorted the two lid position sensors together with a jumper wire. Now when the lid is closed, the input from the LAS brings both inputs to UR300 to ground.

Ah, yes. Mystery solved. I had replaced the display with a A2681 screen since they are otherwise fully compatible. But it's missing the embedded magnet to trigger the open/close sensor (AMR_1V8 stays at 1.8V).

Hold on, is there one or are there two sensors for lid position? I see that this model has an AMR_1V8 line and iI think it's connected to an older-style magnetic Hall effect sensor. A2681 (2022) did away with this sensor in favor of LAS, but in this model A3113 (2024) both sensors are present...