MacBook A2338 - no power, 5V 0A

[survivalbloke]

This macbook came in for a no power complaint. It is stuck on 5V 0A. Serial is FVFDQ2A9Q05F, board is 820-02020-A. I've been trying to check if it is DFU, but I can't get it to come up in Apple Configurator. There is some voltage present on the board, for example CR850:1 has 12.32V. I do not appear to have PP1V_25_S2 anywhere. Any ideas?

[Stephen]

Have you checked PPBUS_AON. 12 Volts seems that it is present however you need 12.60Volts for a normal voltage reading on these boards. Anything less means communication with the SOC or more issues. I would check PPBUS_AON and let us know the readings.

[survivalbloke]

12.32V on PPBUS_AON.

[1centchips]

12.32V on PPBUS_AON.

Have you checked the three caps on the CD chips on the other side of the motherboard?

[Stephen]

12.32V on PPBUS_AON.

You are not getting the correct voltage for PPBUS_AON. You need 12.60 (12.6-13.1v is fine). anything less then read below.

• If the voltage is approximately 12.28-12.35V, it may indicate a communication issue between the SOC and PMICs, or corrupt firmware.

Since it will not DFU restore or revive, you need to resort to looking at the SOC and PMIC's. once you find that short it should boot or DFU restore with ease.

[survivalbloke]

Have you checked the three caps on the CD chips on the other side of the motherboard?

_
Just did that. Odd that I'm not getting the same numbers on both sets of caps. I also have a dead short to ground at PBUS_SPKRAMP_RIGHT_ISNS but it draws no current with voltage injection.

[survivalbloke]

You are not getting the correct voltage for PPBUS_AON. You need 12.60 (12.6-13.1v is fine). anything less then read below.

• If the voltage is approximately 12.28-12.35V, it may indicate a communication issue between the SOC and PMICs, or corrupt firmware.

Since it will not DFU restore or revive, you need to resort to looking at the SOC and PMIC's. once you find that short it should boot or DFU restore with ease.

Any chance of a quick lesson on how to locate the SOC and Power manage ICs? Basically, my skill level is great in soldering, but finding board faults(unless there's a dead short and I use thermal) is not great. Also, my ability to interpret schematics is lacking

[1centchips]

Any chance of a quick lesson on how to locate the SOC and Power manage ICs? Basically, my skill level is great in soldering, but finding board faults(unless there's a dead short and I use thermal) is not great. Also, my ability to interpret schematics is lacking

I am on the same page in terms of reading and predicting the schematics. Take the CD's off and see if you get same diode reading and resistance. I just had a similar a2337 with one overheating bad CD under the thermal camera. It also had very low resistance (ohms) and not kilo ohms/ Mega ohms on the three caps. Took the Cd and put a new one in, still no dice. So, I went ahead and removed the second CD. It worked after that 5V to 20V on the usb c meter. The diode mode readings were in the 0.4 range on the three caps.

[1centchips]

_
Just did that. Odd that I'm not getting the same numbers on both sets of caps. I also have a dead short to ground at PBUS_SPKRAMP_RIGHT_ISNS but it draws no current with voltage injection.

I forgot you had the A2338 lol. But yes both CD's need to work for it to work.

[Stephen]

_
Just did that. Odd that I'm not getting the same numbers on both sets of caps. I also have a dead short to ground at PBUS_SPKRAMP_RIGHT_ISNS but it draws no current with voltage injection.

Oh I had a repair like this. If the speaker Amp is failed this will result in the board not turning on. You should check the speaker area and see if there are any shorted caps. If there are start there and see if it boots.