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[SOLVED] 820-02098 M1 Pro 14" PPBUS partial short

I

iMuhtaseb

Member
Hi,

board came with no signs of life whatsoever, taking only 5V.. measured PPBUS and it was partially shorted (I kinda know this is not an easy one when it's a partial short) around 9 ohms in resistance and 0.012 in diode mode.

Injected 2 volts since 1v was not enough and my initial suspicion was correct it was the haunted TPS62180.. and on board it looked little discolored to my on the visual inspection..
Removed and replaced successfully now left ports take 20V for 2 seconds then switch to 5v and cycle.. on the right side it does not even power on the amp meter.. I replaced the CD3217B12 and it did not resolve the issue..

I measured the diode mode on the LDOs of CD3127 and it seemed OK according to OBD. Where do I look next?
 
I

iMuhtaseb

Member
Yesterday port was not even turning on now the port turns on, on 5V without power draw whatsoever.. I measured;

CC line present 1.6v
PPVBUS_USBC2 5.1v
UPC2_SS not present
PP1V5_UPC2_LDO_CORE present
PP3V3_UPC2_LDO present
PP3V3_S2 not present

although PP3v3_S2 on another USB-C port it is present
 
I

iMuhtaseb

Member
Thinking I may have rushed swapping CD3217s I returned the original one and now CC1/CC2 lines are not present.
I believe it's a CD3217 issue but the one I put is not compatible maybe? I took it from A2338 board..
 
I

iMuhtaseb

Member
I have returned the A2338 CD3217 with ROM chip.. still same thing 5V and CC line 1.6v went back..
I have measured PP5V_S2SW_USBC23 in diode mode and it was very low around 0.108.. I measured both coils and they were still low up until I started to measure PPVIN_5VUSBC23_ISNS my multimeter got stuck and then diode mode reading went up as I watch up to 0.480
IDK what is going on? Is CD3217 pulling it down?
 
2informaticos

2informaticos

Administrator
Staff member
CC1/2 lines must have complementary voltage; depends how the power cable is connected.
Keep in mind, you can connect the cable in two ways on each port.
CC1/2 lines are used to determine if cable is flipped.

People on Internet claims that may be differences between CD3217 chips with small, or big dot marking.
Be sure first to use chips with same termination code.
 
I

iMuhtaseb

Member
B12 on both.. but I've encountered late 2020 MacBooks refusing to some B12s with similar dot size.. they accept certain CDs with the exact board or smilier codes..
What do you suggest?
 
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