A1708 820-00875 5V 0.02A after replaced blown CD3215

[it-solve]

Seems like this had a bad charger as U3200 had a burn mark on the dye.


Replaced U3200 with a "new" one I had, still not powering on, then noticed having short on C3108 - PP3V3_UPC_XA_LDO

I replaced U3100 twice with reballed ones I pulled from another board. Now is stuck on 5V 0.02A with no heat signature. Not sure what is the best way to test the used CD3215 I pulled from donor boards apart than short on LDO lines once I solder them.

PP3V3_UPC_XA/B_LDO - 3.3V
PP1V1_UPC_XA/B_LDO_BMC - 0V - cross-checked on both ports
PP1V8_UPC_XA/B_LDOD - 1.8V
SMC_USBC_INIT_L - 3.41V
SMC_RESET_L - 3.41V

 

[it-solve]

Seems like R3205 was shorting to 0 Ohms. Replaced and still not getting PP1V1_UPC_XA/B_LDO_BMC stuck at 5.2V 0.02A


Diode mode measurements are quite close to these of an A1708 820-00840 I use as a donor.

 

[2informaticos]

"Seems like R3205 was shorting to 0 Ohms"
I never ever saw a resistor shorted.
Do you still have short on UPC_XA_UART_TX.
If yes, change U3100.

Be aware, when you find CD32xx chip with burn mark, the board may be trash.
It suppose die chip was melt and PPBUS_G3H could affected data lines.
These chips are directly connected with PCH/CPU and SMC.
U2890 is also connected with U3200.

 

[it-solve]

No more short on UPC_XA_UART_TX after I replaced it with the expected 1M.
I was just reading about some CD3215C compatibility issues with CD3215B and how TBT ROM could be reprogrammed. I do not have B ones in stock. Could this be something causing it?

 

[2informaticos]

B version doesn't work in place of C; nor viceversa.

Check R3205 value in similar board.
Some Apple schematics show 100K in several resistors from USB-C areas and you will find 0 ohm in real board!

 

[it-solve]

I don't have this exact board for donors, but the two 00840 I have show as 1M.

Perhaps the only option now is to source the B03 version. 00840 and 01041 donors I have are using the C version.

It is a long shot but I do have two TPS65982DA

 

[2informaticos]

The firmware is what import here.
And the end code string specifies firmware version.

 

[it-solve]

Replaced the charging chip with the B version. It worked fine and passed all tests. Left on the shelf, and the customer came to pick it up. Not turning on

Back to the repair bench. I am getting 20V 0.02A. No short circuit on coils, and no heat signature.

PPBUS_G3H - 13.05V
PP5V_S5 - 5.1V
PP3v3_S5 - 3.3V
PP5V_S4 - 0V

 

[2informaticos]

Tried with battery connected?
Check if SMC reset helps.

I suspect bad solders; reflow the area.

 

[it-solve]

Reflowed, it seems to be the same. 20V 0.20A Initially, after a couple of seconds drops and stays at 20V 0.02A board only. 20V 0.5A with battery.
Tried a different case 20V 1.2A seems to be charging. But not turning on

SMC reset didn't work

 

[2informaticos]

Was the machine still used with the same charger which damaged it?

 

[it-solve]

Oh no, the customer didn't have a chance to pick it up. was staying on the shelf charged.

 

[2informaticos]

Bad solders, broken traces, internal board damage...

 

[it-solve]

Would we get 20V and these readings if the 3215's are malfunctioning?

PPBUS_G3H - 13.05V
PP5V_S5 - 5.1V
PP3v3_S5 - 3.3V
PP5V_S4 - 0V

 

[2informaticos]

USB-C area may be good.
Something else has been affected by heat.

Check diode mode to ground on big coils; compare with good board.
Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L.

 

[it-solve]

Reflowed the area on both sides to see if any change, but the same.
I get a drop pulse on PM_PWRBTN_L when SMC_ONOFF_L 3.3V is triggered.

 

[2informaticos]

Check for pulse at PM_SLP_S4_L, at same time.
If present, some pulse must be detected on big coils too.

 

[it-solve]

No PM_SLP_S4_L pulse when SMC_ONOFF_L is triggered

 

[2informaticos]

Then you have PCH related issue.
Check its basic power on and RTC signals.

 

[it-solve]

PP3V3_S5 - 3.3V
PP1V_S5G - 1V
PP1V8_S5G - 1.8V
PP3V3_S4 - 0V
PP3V1_RTC - 3.08V
RTC_RESET_L - 3.07V

Thanks for your help