Macbook Pro 2017 15" 820 - 00138 - A Not powering on, Voltages pulsing, 30mA to 200mA

[worldofskin]

Hi guys ! Hope you are having a lovely day. This macbook pro came to the shop not powering on. Board is 820 - 00138. Its a macbook pro 2017 15". After disconnecting everything from the board and puting it on a charger i got 25-30mA. Right when i connect the charger i hear a click on the board. when i disconnect the cable i need to wait like for 5-10sec so the click happens again.If i put it back right away no click can be heard. I thought there may be a short somewhere but i cannot find it. so i checked power rails from the schematic. All the S5 rails were there. I think when i cleaned the area around clock generating circuit the board started pulling more current. When i plug it in its taking more like 30mA but it jumps every like 5sec to 200-250mA current draw. When it does all of the power rails pulse. Even PPVCC_S0_CPU is at 1,7V. So i thought okay it looks like a bad bios chip. I pulled it off. The chip was - 25Q64FVSIG . without the bios chip the board jumped to around 200mA and stayed. All the powerrails with the voltage they are supposed to. After trying to read the chip i got a full FF file. The chip was dead. I replaced it with a different chip MX25L1006E whitch is a 64Mbit chip too. and i am back at the pulsing and current draw 30mA to 200mA. This is my first post so if you see any mistakes please comment it i will improve. Thanks in advance have a nice day )

[kurland]

Re: Macbook Pro 2017 15" 820 - 00138 - A Not powering on, Voltages pulsing, 30mA to 2

Use procedure described here to check your pwr signals. It's for 820-00165, which is mostly the same as your 00138, chip references etc.

https://www.it-tech.com.au/mac-q-a/c...0_cpu-voltage/

[ACS-Repair]

Re: Macbook Pro 2017 15" 820 - 00138 - A Not powering on, Voltages pulsing, 30mA to 2

The 820-00138 board is a 2015 model MacBook Pro, not 2017. It could have been manufactured in 2017.
With your EFI chip, it is more likely that you had a read error rather than the EFI was blank (all FF). It is a good idea to get a good read on those chips before doing swapping.
Pulsing voltages usually means you have a short somewhere. keep looking. I'm sure you'll find it.

[worldofskin]

Re: Macbook Pro 2017 15" 820 - 00138 - A Not powering on, Voltages pulsing, 30mA to 2

Use procedure described here to check your pwr signals. It's for 820-00165, which is mostly the same as your 00138, chip references etc.

https://www.it-tech.com.au/mac-q-a/c...0_cpu-voltage/

Thanks for your reply, i did indeed try to use this procedure but only thing i got to is that i've got all of those power rails. i just cannot get to why it is powercycling.

[worldofskin]

Re: Macbook Pro 2017 15" 820 - 00138 - A Not powering on, Voltages pulsing, 30mA to 2

The 820-00138 board is a 2015 model MacBook Pro, not 2017. It could have been manufactured in 2017.
With your EFI chip, it is more likely that you had a read error rather than the EFI was blank (all FF). It is a good idea to get a good read on those chips before doing swapping.
Pulsing voltages usually means you have a short somewhere. keep looking. I'm sure you'll find it.

You are totally right, the bios was alright and it was not blank. I backed up the dump. i am really trying to find the short but no luck so far. Actually in the end i found a short on clock circuit so i changed the crystal and the chip too. No short anymore, the 33kHz rtc and 25MHZ clocks are there. Still no luck. I found a broken corroded cap C7150 between trace chgr_cso_n and chgr_cso_P, repaired the broken trace under it. then i found a short (1ohm) between gate and source of Q7130(PPBUS_G3H mosfet). so i changed both mosfets and the chip with them to be sure. Still no change and the short between G and S is there again. Dont know if its normal i think not. But you may be more experienced then i am. Please any of your ideas will be very helpfull i am sure. Have a great day guys )

[reformatt]

Re: Macbook Pro 2017 15" 820 - 00138 - A Not powering on, Voltages pulsing, 30mA to 2

If you are getting all rails up to CPU Vcore, why are you mucking around in the PBUS Supply? Replacing components for the sake of it only introduces more potential issues, especially if you don't know the voracity of the parts.

Power cycling means you either have a short somewhere (use a thermal camera) or it's not able to read the BIOS.

[worldofskin]

Re: Macbook Pro 2017 15" 820 - 00138 - A Not powering on, Voltages pulsing, 30mA to 2

You are right, actually i got a little frustrated and i just started to repair the PBUS supply. nevermind lesson learned. i will try to reflash the bios. If it wont change i will leave the mb without bios and turn it on becouse thats only time it consumes 200mA all the time.(But what does it say? i dont understand why it would be at 200mA all thetime without a bios :/) i dont have a thermal camera. i will keep looking thanks for the advice.

If you are getting all rails up to CPU Vcore, why are you mucking around in the PBUS Supply? Replacing components for the sake of it only introduces more potential issues, especially if you don't know the voracity of the parts.

Power cycling means you either have a short somewhere (use a thermal camera) or it's not able to read the BIOS.

[reformatt]

Re: Macbook Pro 2017 15" 820 - 00138 - A Not powering on, Voltages pulsing, 30mA to 2

Try a good donor clean ME BIOS, then check your SPI Bus termination resistors for corrosion, bad test points etc.

You might also want to check U1100 (PCH) and it's resistance to ground on L7630. Seen these just go short for no reason.

[worldofskin]

Re: Macbook Pro 2017 15" 820 - 00138 - A Not powering on, Voltages pulsing, 30mA to 2

I tried a new bios, in the process i overheated a 3.3 G3H supply. it started generating 7V i did not respond as quick as i should. It killed smc it seems like. The board draws now 235mA all the time and the only thing that goes hot is smc. Nevermind i will give it to a good known technician. Thanks so much for the replyes again. I am smarter going out off this problem. I will post after the technician will repair it ) good luck guys.