MacBook A1706 No Power; 20v present on board

[ResoluteHawk]

I have a Macbook A1706 that won't turn on. It did have signs of liquid damage under U7650 so I replaced the chip. No changes.

I then went to measure a see if PP3V3_G3H is present on R7009. It is indeed present at 3.4v.

However, PPBUS_G3H on F7000 measures 1.1v without the battery installed.

A USB-C amp meter initially shows 5v in but then goes up to 20v. 0 amps are present as the board is not turning on. No fan spin either.

[mon2]

Re: MacBook A1706 No Power; 20v present on board

Remove the fuse @ F7000. Power up again and test if the PPBUS_G3H voltage returns on the ISL side of this power rail.

What is the voltage to ground without the fuse and load applied ?

Next, remove all power -> measure the RESISTANCE to ground of the consumer (downstream) side of this removed fuse (F7000).

What is the resistance to ground reading ?

[ResoluteHawk]

Re: MacBook A1706 No Power; 20v present on board

Still no PPBUS_G3H. Voltage on ISL side is 0.064v.

Resistance to ground on downstream side with fuse removed => 4.7k Ohms.

EDIT: The above measurements were with the battery installed.

[mon2]

Re: MacBook A1706 No Power; 20v present on board

What is the 820-**** number of your logic board ?

Remove all power. Measure the resistance to ground of the ISL side (F7000, pin # 1).

What is the reading ?

[ResoluteHawk]

Re: MacBook A1706 No Power; 20v present on board

820-00923a

Without the battery and no charger plugged in, voltage on ISL side is .08v and resistance to ground is north of 2M Ohms.

My mistake. I thought by downstream you meant pin #2 of F7000.

[mon2]

Re: MacBook A1706 No Power; 20v present on board

Plug in the Type C adapter -> confirm you have 20 volts being selected.

Then measure the voltage to ground on the ISL side.

With a 20 volts as the input, the ISL device will enter BUCK regulator mode (high input voltage -> lower output voltage).

If the input is 5 volts on the adapter, ISL device will enter BOOST regulator mode (low input voltage -> high output voltage).

What is the voltage to ground with the power adapter plugged in on the ISL output ?

[ResoluteHawk]

Re: MacBook A1706 No Power; 20v present on board

Wit the type-C plugged into the amp meter and then into the laptop, the amp meter shows 5v for maybe 1 second, then it goes up to 20v.

At Pin 1 of F7000 (removed from board), measurement in voltage mode is 0.13v.

[mon2]

Re: MacBook A1706 No Power; 20v present on board

Power up with the same adapter. The selection of 20V is good and confirms that the CD3215 ACE controllers are working.

Measure the voltage to ground (with the power adapter connected) for:

SMBUS_SMC_5_G3_SCL
SMBUS_SMC_5_G3_SDA

Red meter probe to one of the above points; black meter probe to ground.

Post each measurement.

[ResoluteHawk]

Re: MacBook A1706 No Power; 20v present on board

Smbus_smc_5_g3_scl => 0v
smbus_smc_5_g3_sda => 0v

Seriously starting to wonder if our ISL chip (U7000) is bad.

[mon2]

Re: MacBook A1706 No Power; 20v present on board

That is not good.

Remove all power. Meter in DIODE mode.

Red meter probe, yes RED to ground .
Black meter probe to one of the same test points as above.

What is the measurement? Then repeat for the other test point.

We are checking if this open-drain interface pin is being shunted to ground.

Moving forward, suggest to flux + low air pressure -> remove the dual ESD device @ D6950. This is a tiny tiny bugger so proceed with patience.

Then power up again and check the VOLTAGE to ground of these pins again.

[mon2]

Re: MacBook A1706 No Power; 20v present on board

ISL chip (U7000) is bad

Not yet - review my last post. Repeating again that I killed 3 days to locate this nasty fault on a macbook about to be dumped in the garbage bin. D6950 was to blame.

[ResoluteHawk]

Re: MacBook A1706 No Power; 20v present on board

So I made a pretty rookie mistake; I actually measured the wrong location.

Pin 2 is 0V; Diode mode shows 0 Ohms to ground.
Pin 3 alternates between 3.3v and 2.6 and in between the two. 0.45 voltage drop in Diode mode.

Woops.

[mon2]

Re: MacBook A1706 No Power; 20v present on board

Do confirm that R5381 is present.

Remove D6950 and test again.

[ResoluteHawk]

Re: MacBook A1706 No Power; 20v present on board

With D6950 removed, voltage measurement at pins 2 and 3 are the same.

[mon2]

Re: MacBook A1706 No Power; 20v present on board

Ok. Now check PPBUS_G3H at the ISL side.

[ResoluteHawk]

Re: MacBook A1706 No Power; 20v present on board

R5381 is present at 3.4v on pin 1 and 3.3v on pin 2.

[ResoluteHawk]

Re: MacBook A1706 No Power; 20v present on board

Still getting 0.13v at ISL side on F7000.

[ResoluteHawk]

Re: MacBook A1706 No Power; 20v present on board

So I went ahead and replaced the ISL 9239 chip, and tested again without the fuse on the board.

We had PPBUS_G3H and the amp meter read that current was actually being drawn by the board.

However, when I went to put the fuse back (F7000), the heat from the heatgun must have loosened the ISL chip because I noticed that it was raised slightly on the left side and the amp meter was reading 5v after putting the fuse back on. I then tried to put the ISL chip back down on the side that was raised but it moved just a little too much and the chip is just shot at this point and I don't have a stencil to reball it. Luckily those 9239 chips are not expensive.

So to make a long story short, the board worked after replacing the ISL 9239 chip, but I botched the repair shortly after and I'm mad at myself.

Going to get another ISL 9239 chip but this time I'll do it with the fuse already on the board.

[ResoluteHawk]

Re: MacBook A1706 No Power; 20v present on board

Replaced the ISL 9239 chip and we have PPBUS_G3H, power on, and successful boot!