A1708 820-00840-A 5V 80-100mA

[Aitorflores7]

Hi all!
I´m new troubleshooting MacBooks and I need a little help. I have A1708 13" Macbook Pro stuck in 5v 27-33mA. Sometimes go up to 50mA and then back to 30mA. Also sometimes go down to 0mA and restart the cycle again(27-33mA). I have checked all the voltages in U3200 (https://logi.wiki/index.php/CD3215_Bootup_Sequence) and the only one that is missing is PP1V1_UPC_XB_LDO_BMC. The G3H rails that I have are cycling. No PPBUS_G3H. What should I do next? THANK YOU FOR HELPING ME!

[Win Me]

Re: A1708 820-00840-A 5V 80-100mA

Hello, do you have PP3v3 G3Hot?

[Aitorflores7]

Re: A1708 820-00840-A 5V 80-100mA

Hello! Yes, I have pp3v3_g3h

[Aitorflores7]

Re: A1708 820-00840-A 5V 80-100mA

pp3v3_g3h rail and other g3h rails are cycling

[Win Me]

Re: A1708 820-00840-A 5V 80-100mA

Interesting! Is PM_EN_P3V3_G3H_R cycling too?

[Win Me]

Re: A1708 820-00840-A 5V 80-100mA

And check PPDCIN_G3H_CHGR if it is cycling too. Try to test on the two USB-C ports and see if on both you have 5V and the same amp draw

[Aitorflores7]

Re: A1708 820-00840-A 5V 80-100mA

Yes, PM_EN_P3V3_G3H_R and PPDCIN_G3H_CHGR are cycling too. I compare the 2 usb-c ports and the amp draw is the same, they are doing the same cycle i mentioned in the first post

[Win Me]

Re: A1708 820-00840-A 5V 80-100mA

I think there might be a problem on a G3H rail, test ALL the G3H rails and check for shorts (I had a similar amp draw one time on this board it was a short on a G3Hot rail). It coulmd also be a sensor issue around the ISL, so check resistors around the ISL9239 and also caps for shorts.

[mon2]

Re: A1708 820-00840-A 5V 80-100mA

Place your meter in resistance mode (2k). Remove all power. Check for any low resistance to ground on each and every coil on the logic board. Looking for any low resistance reading which may indicate a shorting cap = excessive current draw = power cycling to make it safe (chirp mode).

[Aitorflores7]

Re: A1708 820-00840-A 5V 80-100mA

I think there might be a problem on a G3H rail, test ALL the G3H rails and check for shorts (I had a similar amp draw one time on this board it was a short on a G3Hot rail). It coulmd also be a sensor issue around the ISL, so check resistors around the ISL9239 and also caps for shorts.

Could you tell me what g3h rails do i have to check? maybe im missing someone. I chech everything around isl9239 and no shorts found. Also the resistors i think they are reading ok. Do i have to post any readings?

[Aitorflores7]

Re: A1708 820-00840-A 5V 80-100mA

Place your meter in resistance mode (2k). Remove all power. Check for any low resistance to ground on each and every coil on the logic board. Looking for any low resistance reading which may indicate a shorting cap = excessive current draw = power cycling to make it safe (chirp mode).

I think i have check all coils of the board, but im not sure. Some coils have low ohm readng due to are connected to the cpu, am i right?

[Win Me]

Re: A1708 820-00840-A 5V 80-100mA

On the schematic you have a list of all the power rails, if there is G3Hot in the name of the rail test it. Yes Coils around the CPU have a low resistance to ground. Place a probe point on PPBUS_G3_HOT and the other on coils around the CPU, if you see no resistance it is probably a dead CPU

[Win Me]

Re: A1708 820-00840-A 5V 80-100mA

You said some rails are cycling, does the amp meter is cycling too?

[Aitorflores7]

Re: A1708 820-00840-A 5V 80-100mA

On the schematic you have a list of all the power rails, if there is G3Hot in the name of the rail test it. Yes Coils around the CPU have a low resistance to ground. Place a probe point on PPBUS_G3_HOT and the other on coils around the CPU, if you see no resistance it is probably a dead CPU

I have tested now all the G3Hot rails and no shorts. Between ppbus and cpu coils 1,2Mohms

[Aitorflores7]

Re: A1708 820-00840-A 5V 80-100mA

You said some rails are cycling, does the amp meter is cycling too?

No, is what surprises me. The amp meter stays on and only changes the amp draw.

[Win Me]

Re: A1708 820-00840-A 5V 80-100mA

Well, I would most likely think of a CD3215 issue or an ISL9239 issue. It could be a Thunderbolt ROM issue, but with a 50 amp draw I doubt. If only one of the two CD3215 fail then the other one will not work

[Win Me]

Re: A1708 820-00840-A 5V 80-100mA

Have you also check the board visualy, Try to see if there are not any corrosion, cracks on capacitors, burn marks, etc

[Aitorflores7]

Re: A1708 820-00840-A 5V 80-100mA

Have you also check the board visualy, Try to see if there are not any corrosion, cracks on capacitors, burn marks, etc

The board is super clean. No dust,no corrosion...

[Aitorflores7]

Re: A1708 820-00840-A 5V 80-100mA

Well, I would most likely think of a CD3215 issue or an ISL9239 issue. It could be a Thunderbolt ROM issue, but with a 50 amp draw I doubt. If only one of the two CD3215 fail then the other one will not work

So im going to buy some cd3215 and check if that solve the problem. If i remove the two cd3215, rails should stop cycling?

[Win Me]

Re: A1708 820-00840-A 5V 80-100mA

If you remove them you will get nothing, maybe try to remove R7020 and D6905 first and see if it is still cycling. If still most likely the CD3215, if not the probably an ISL related issue