A1534 No power

[mon2]

Hi. Troubleshooting a macbook A1534 that will not power on. Computer appears to have some liquid (thin line) around the perimeter of the logic board and suspecting it is from the topside keyboard / trackpad area. No wet tag color sensors were triggered. Will review to clean it with an ultrasonic cleaner.

So far, applied an external Apple type C power adapter which emits 14.5v (approx.) after USB negotiations.

The current draw on the unit itself is oscillating between 30 mA and 0.6A.

The CPU shield area is warm to the touch. Some of the tantalum caps are @ 52 C after a few minutes of on time using an IR thermometer gun. The rails related to these caps are operating fine @ 8.6 volts (C1031 & C1032).

PP1V1_S0SW_SSD = 0 volts

PPBUS_G3H @ 8.6 volts which matches the value on sheet 60 of 75 PDF.

PPVIN_G3H_P3V3G3H @ 14.5 volts (same as input supplied by external power adapter) - but should be 8.6 volts (according to sheet 60).

Confused as to the start / end of this PPVIN_G3H_P3V3G3H rail.

From which feed does PPVIN_G3H_P3V3G3H get the 8.6 volts?

If PPVIN_G3H_P3V3G3H = 14.5 rather than 8.6 volts, does this imply that U7100 (ISL95530HIZ) is damaged? From my understanding, U7100 is to use the PPVIN_G3H_P3V3G3H as a Vcc so is an input to this switcher?

Please confirm. U7100 is quite expensive and may just conclude this motherboard to be not worth repairing.

Welcome any suggestions on this repair.

reference - downloaded the schematics & boardview brd file from this forum:

macbook-pro-a1534-82000045a-j92-schematics

Thanks!

[piernov]

Re: A1534 No power

Don't trust the voltage indications on the schematics, lots of them are wrong. If you get PP3V3_G3H, there's no reason to suspect having an issue on PPVIN_G3H_P3V3G3H.
Additionally, if PPBUS_G3H is good (it is) and SMC_RESET_L is present, there's no reason to suspect U7100 at this point.

As always, start by going down the list of power rails.

This will probably end up having a dead CPU anyway.

[mon2]

Re: A1534 No power

Thank you.

Will continue to check the rest of the voltages today and post the details.

At which stage can we confirm the CPU is dead?

Would the USB type c contract negotiations still function without the CPU? Or the texas instruments type c controllers are autonomous?

Thought that the CPU is the i2c bus master and then configures the type c slaves. Meaning the cpu is still alive.

We are in talks but cannot justify the expense of a bga rework station yet from Seamark that could potentially remove and replace the cpu. Not an easy chore with just got air tools considering the high density of small parts near and underside of the cpu.

Thanks so much for your advice!!

[Der Schwede]

I have same board and similar problem. Just that the rails has power just on PP5V_S4 the voltage is fluktuating.

PPBUS_G3H Has 8,58v

PP3V3_G3H Has 3,29v

PPVRTC_G3H Has 3,,28v

PP5V_G3H_LDO Has 4,98v

P5VS4_PHASE 200 kohm 0v

PP5V_S0 20 mohm 0,1v

SMC_RESET_L Is not present

PP1V1_S0SW_SSD 1,113v

TP(1)PPIN_G3H_P3V3G3H 14,75v

From where does PP5V_S4 Get voltage from

What could make PP5V_S4 Fluktuating?

Thanks in advance.

[mon2]

What is the 820-**** number of your logic board? Is it 820-00045 or 820-00244 ?

See attached. This rail is enabled by the signal P5V_S4_EN. Check its voltage to ground to see if it is cycling or not. Note that PP5V_S4 may be fluctuating if it believes there is an excessive load on this rail. Your resistance to ground is OK and is not a short BUT the current sense circuit could be providing for the incorrect current or FB measurements. For this reason, remove all power -> meter in the lowest resistance scale -> measure the resistance of the current sense path or FB voltage leg. One meter lead @ L7510, pin # 1 and other meter lead @ R7510, pin # 2 - to confirm that the FB resistor @ R7510 is of the correct value and is not defective.

P5V_S4_EN will be difficult to probe since this signal STARTS under a BGA and ends under a BGA. Review the resistance of R7510 first.

Update - sorry - meant R7510 = should be 10 ohms and is the FB resistor.

[Der Schwede]

Hello Mon2 The number is 820-00045

[mon2]

Ok - we are referencing the same schematic. Personally this is one of the boards I hate as the parts are incredibly small. Ironically, we are shifting to build products using 0201 with our machinery but it is different when you have the joy to service a finished product with such tiny parts. Hope your eyes are better than mine or at least have a good microscope.

[Der Schwede]

Yes, microskope i just got one crapy electronic which connects to latop. But i dont use it now.. :/

L7510 pin 1 to R7510 in2 10ohms

PP5V_S4_EN 0.2mv

[mon2]

Great. Carefully check if this enable pin (P5V_S4_EN) with the power adapter connected is pulsing or not. Measure the voltage to ground of the same test point that you have found.

[Der Schwede]

No, not fluktuating but only 0,2mv

Is that mean that i have a problem in u7400? I Have an sparearts board due i bought 2 same A1534 with about same issue. But i dont know if the u7400 chip is good from the another board.. And i dont have bga balling equippment, so i hope its not an issue with the u7400 chip.

[mon2]

Not at my desk but this is an active high enable pin. If a logic ‘1' then the mentioned missing power rail will enable. On this note, the missing power rail should be 0 volts or very close to it and not turning on / off. Since the enable is a logic ‘0', this local power rail should be off.

wait on other comments but the fault may be a corrupt bios. Bios reflashing may be required but do check if the bios has a voltage that is stable to boot the board. Would you have flash programming tools? You must back up the current flash first. Check its power rails and also the Spi lines for a voltage.

[Der Schwede]

Yes, I got progrmming tools. And board was booting untill Apple logo ant then went off.

SPI_MLBROM_CS_L 0V
SPI_MLB_IO<3> 2mv
SPI_MLB_MISO unstable 4,6-6mv
SPI_MLB_CLK 0,2mv
SPI_MLB_IO<2> 0,7mv
SPI_MLB_MOSI 1,6mv

[Der Schwede]

PP3v3_S5 Have 3.3v

I have been looking around how to connect the bios chip. The chip is very small and they use a connector to the board and with the connector they read/programm the bios chip.

I dont have this connector, can it be soldered of the board and read it or do I need to solder kables to the board?

But i dont think my programmers support this efi/bios chip from the A1534 board.. I got the CH341A with 1,8v modd and an EZP2023+. The EZP2023+ suport 24/25/26/93/95 series chips and i dont know which type chip the EFI/Bios chip is from the A1534 board.

EDIT.....

I read on the net that its possible to read but there is an write protection on the chip. And i read It could get rid of the protecton with some efipassword eliminator! Im little stuck right now.

If i somehow manage to read the chip i will not be able to write on it anyhow.

EDIT 2....

I found a connector which fits on the CH341A programmer and others also. I need to buy one of those. SPI Rom EFI Ribbon Cable Hirose 12 Connector Service A1534