A1706 820-00239 Looping on all ports

[Markus Plutka]

Hi,
bought a liquid damaged device and am trying to get it fixed as a hobby.
U7600 was shorted and got replaced. Now all ports power cycle after 2 seconds and none negotiates 20 Volts. Ldo bmc reaches 1.1 v on all before the cycle begins again. PP3v3_G3H is at 3.3v.
i checked this sequence https://logi.wiki/index.php/CD3215_Bootup_Sequence and get the correct voltages for step 10 (SMBUS_SMC_4_G3H_SCL and SMBUS_SMC_4_G3H_SDA) with 3.4 v each. I don’t use an original charger but one from my Huawey notebook with 65 w. Could this be the cause? Thanks a lot.

[Markus Plutka]

Doesn’t work even with an original charger. What is curios, one port only draws current if the cable is plugged in in a certain way. If I turn it around , the port is dead. This isn’t like this with the other 3 ports

[mon2]

Inspect the paddle board with the USB connector for possible damage.

Suggest to use a USB-C meter or the 'Tail tester' by Qianli which is also able to offer diode mode readings of the same batch of signals.

If you see the port going dark with the meter then there is a short on that side of the USB-C blade. That PD controller is also a suspect. As per the CD3215 articles on logiwiki- check each and every LDO rail on the PD controller.

What is the voltage of PPBUS_G3H to ground? Remove the fuse on that rail and measure again if out of spec here.