A2251 820-01949-A no power

[hgoncalves]

Hi,

I have an A2251 820-01949-A with no power.

It had water contact on the USB-C conector, and stoped working.

All USB-C ports were consuming 5.26V and 0.25A, with exception of U3100_X, that was pulling 0A. After replaceing U3100_X, now that port also pulls 0.25A, but all ports only have 5.26V

Can you help?

 

[2informaticos]

Did you check CD3217 LDOs?
Post U7000 basic voltages; P_IN, AUX_DET, SMC_RST_IN, VDDA/P, EN_MVR, CBC_ON, A/BMON.

 

[hgoncalves]

U3100_X diode readings:

PP3V3_UPC_X_LDO = 0.510
PP1V5_UPC_LDO_CORE_X = 0.523
USBC_X_CC1 = 0.590
USBC_X_CC2 = 0.590

U3100_T diode readings:

PP3V3_UPC_T_LDO = 0.511
PP1V5_UPC_LDO_CORE_T = 0.525
USBC_T_CC1 = 0.590
USBC_T_CC2 = 0.591

U3100_R diode readings:

PP3V3_UPC_R_LDO = 0.515
PP1V5_UPC_LDO_CORE_R = 0.527
USBC_R_CC1 = 0.588
USBC_R_CC2 = 0.586

U3100_W diode readings:

PP3V3_UPC_W_LDO = 0.507
PP1V5_UPC_LDO_CORE_W = 0.529
USBC_W_CC1 = 0.597
USBC_W_CC2 = 0.597

U7000 basic voltages:

AUX_DET = 1.282V
SMC_RST_IN = 0V
VDDA = 5.150V
VDDP = 5.140V
EN_MVR = 5.150V
AMON = 0.050V
BMON = 0V
CBC_ON = couldn't find where to measure it. Can you help?
P_IN = couldn't find where to measure it. Can you help?

 

[2informaticos]

"P_IN = couldn't find where to measure it."
Use the logic when you work; can't find R7020?
How did you find other signals?
Don't bother with it now; P_IN is good, if get VDDA/P.

I was expecting voltage readings for CD3217 LDOs.
Do you get PPBUS_G3H at least?

Check diode mode to ground on J3300_CXT/CWR pins and compare with good board.
Or compare at least left/right sides.

 

[tcampbell34]

U2800 could also cause the this board to be stuck at 5v. I had one with the same issue as you, and did not get 20v until I replaced U2800_X and U2800_T.

 

[hgoncalves]

" Use the logic when you work; can't find R7020? "
Sorry, my bad.

All CD3217 LDO´s have the right voltages (1.5V and 3.3V)
PPBUS_G3H = 12.29V

I don't have a good board to compare diode readings, but comparing connectors on both conectors, all readings are identical

 

[2informaticos]

Try DFU.
Lets see if is recognized in AC2 at least.
AWAKE and SLPS2R voltages must come on.

 

[hgoncalves]

Hi,

The DFU revive worked. It boots again. However, it is not charging the battery. It pulls 20V but 0A from ampmeter.

 

[2informaticos]

Does it work with charger alone (without battery)?

 

[hgoncalves]

No it doesn't. With the battery disconected it only pulls 5.16V.

Now that the battery went gone, it don't power on.

With the battery conected it puls 20V, 0A from ampmeter but no power on.

 

[2informaticos]

Check UPC_I2C_INT_L.
If low, you have a problem on USB-C area.

 

[hgoncalves]

Hi,

R3208/9 had normal resistance values (1M ohm) but had small bit of corrosion, and after replace them, the mac started to work normnally.

TKS!