MacBook A2337 Touchpad und Tastatur Funktionsstörung Reparatur

MacBook A2337 Touchpad und Tastatur Funktionsstörung Reparatur

Defekt-Phänomen

The MacBook Air 2020 A2337 works normally, but on the second day, the touch bar and home button functions both failed.

Fehlersuche

Disassemble the phone and we find the flex cable connector of the touch bar with some problems

A part of the buckle on the connector is missing

Put back a buckle under the microscope carefully

After that, test again. The touch bar and keyboard functions are still not working. The issue should come from the motherboard

Take out the motherboard, and measure the diode value on the IPD B2B connector JT400#

All the diode values are OK. 

Then connect with the DC power supply and measure the voltage values. After measuring, we find that pin 29# (PP5V_S2_IPD_F) voltage value is abnormal. 

Keep tracking the schematic, and we find the 5V voltage is provided by the UC840.

The basic working conditions for the UC840 including power and enable

• PP5V_S2
• P5V_S2SW_IPD_EN

So we should keep tracking the enable signal, after searching the schematic. The signal is outputted from the chip UC870

Measure the basic working conditions of the UC870,

• P5VS2_PWR_EN
• IPD_PWR_EN 

All values are OK.

So there is a high chance, that the touchpad and keyboard issue should be caused by the UC870 being damaged.

Find this chip on the motherboard and replace it with a new one

After replacing, and measuring the voltage value on the chip UC840 again, the voltage value on the ENABLE signal (P5V_S2SW_IPD_EN) is back to normal.

Then assemble the MacBook and test again, both the touch bar and keyboard function back to normal.

Zusammenfassung

The A2337 touchpad and keyboard function failure issue get fixed by UC870 (IPD_PWR_EN Gating Logic) replacement.

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