820-01949 after replacing CD32 no usb-c communication

[meineiid]

Hi I got a MacBook A2251 2020 with only 5volt on usb-c. Replaced both CD32 on the right side and got 20 volts back on all ports and Macbook starts normally. But USB devices don't work no usb3 or thunderbolt ist working. My external SSD gets Power but no blinking...
Any ideas?

[PITERPENY]

cd3217 from a similar donor board or from Aliexpress?

[meineiid]

i think i took it from 820-01700.
Oh no do i need it from same board? tought only the "new" 14 and 16 inch need from same Board/Position

[PITERPENY]

Each 3217 has an installation order according to the diagram. 1/2/3/4 on boards with four ports and 1/2 with two-port. In no case should they be swapped, incorrect operation is possible! But in no case should you install 3217 with two ports on a four-port board and vice versa. This will not work. Before removing, number the CD.

[meineiid]

wanted to let you know I got the right CD32 for A2251 and now everything is working fine. Thanks!

[PITERPENY]

wanted to let you know I got the right CD32 for A2251 and now everything is working fine. Thanks!

[Oranium 2015]

🧩 MacBook Pro A2251 (820-01949) – Finding correct OTP CD3217 placement for 20V negotiation
Hello,
I’m repairing a MacBook Pro A2251, board 820-01949, and I’m currently stuck at the USB-C power negotiation step. The board pulls 5V / 0.15A, but never requests 20V from the USB-C charger.

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🧠 Context:
All four CD3217 chips (U3100_W, X, R, T) were previously desoldered. I kept the four original chips (all labeled CD3217B12 13POVCS) but did not note their original positions.
I have now resoldered only two CD3217s:

• U3100_W
• U3100_R

U3100_X and U3100_T are empty (X pads are damaged).

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🔍 My current goal is NOT to boot the system.
Instead, I want to:

• Identify the correct original CD3217 for W and R (since these use OTP I²C addresses).
• Find out if correctly matching OTP chips at W and R is enough to trigger 20V PD negotiation, using a USB-C power meter.

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📌 Understanding of board design:
According to LogiWiki CD3217 OTP diagram:

Position	Label	I²C Address Type	Swap Possible
U3100_W	OTP	❌ Hardcoded	❌ Not interchangeable
U3100_X	Strap	✅ Configurable	✅ Interchangeable with any strap
U3100_R	OTP	❌ Hardcoded	❌ Not interchangeable
U3100_T	Strap	✅ Configurable	✅ Interchangeable with any strap

From what I’ve learned, all 4 CD3217s must be detected properly via I²C for any of them to request 20V from the charger. But...

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❓ Main question:
If I populate only U3100_W and U3100_R with the original CD3217s (OTP),
and leave U3100_X and T empty,
can the board still request 20V — but only if W and R are in the correct positions?
If yes, I’ll try all combinations of the two OTPs to see when 20V appears (12 total combinations).
If no — I’ll know the system requires a complete I²C chain (all 4 chips) for USB PD to reach 20V.

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🛠️ Bonus question:
If I cannot identify the original OTP chips or they are damaged:
Is there any known method to populate all 4 ports with new CD3217s (strap-based or otherwise), and bypass the OTP address lock for proper I²C communication?
Or is the OTP limitation hardwired and non-replaceable?