MacBook Pro A1706 820-00239 no power

[mon2]

Re: MacBook Pro A1706 820-00239 no power

Remove all power. Meter in resistance mode.

What is the resistance to ground of PICCOLO_VEN1 ?

We want to confirm that an excessive load on this signal line is not pulling down the enable voltage.

After this check, consider to remove with care, the 0 ohm resistor @ R9420.

Then power up again and check the voltage @ R9420, pin # 2 to ground.

Do you have a valid EN voltage now ?

Use ample flux + low air pressure and enough hot air temp to remove the part. Do not lose the part but if lost, you can bridge it later with a blob of solder.

[Xenoaeuriix]

Re: MacBook Pro A1706 820-00239 no power

PICCOLO_VEN1 to GND = 1.680M oHms

Then power up again and check the voltage @ R9420, pin # 2 to ground. = 0.020

Do you have a valid EN voltage now ? = I am not sure what is the valid voltage but I got 0.020

Use ample flux + low air pressure and enough hot air temp to remove the part. Do not lose the part but if lost, you can bridge it later with a blob of solder. = I manage to remove it without losing it. Max temp @ lowest air.

[mon2]

Re: MacBook Pro A1706 820-00239 no power

With care, remove R9401 and R9406.

These resistors are in series to power this regulator.

Place them aside for use after this repair.

After the parts are removed, check if the short is still present on PPBUS_G3H.

[mon2]

Re: MacBook Pro A1706 820-00239 no power

Wish to stress to NOT power up with these resistors removed.

Only check the resistance to ground of PPBUS_G3H after the last step.

Do you still have the hard short?

[Xenoaeuriix]

Re: MacBook Pro A1706 820-00239 no power

With care, remove R9401 and R9406. = Successfully removed.

After the parts are removed, check if the short is still present on PPBUS_G3H.
= Yes the short is still present ( I have already re-attached the F7000 and have accidentally knocked out the C7054 I hope that it is not an important capacitor.

[mon2]

Re: MacBook Pro A1706 820-00239 no power

Remove F7000 again.

Inject 1 volt (not higher) again onto the fuse pad that shows the short. Increase the current a bit if required.

Monitor who heats up. Does the regulator you have worked on heat up? Do also monitor the output side mosfets present on the same voltage rail.

If still not found, check the resistance to ground of each large coil / inductor. Note any very low resistance readings.

[Xenoaeuriix]

Re: MacBook Pro A1706 820-00239 no power

Remove F7000 again.

Inject 1 volt (not higher) again onto the fuse pad that shows the short. Increase the current a bit if required.

Monitor who heats up. Does the regulator you have worked on heat up? Do also monitor the output side mosfets present on the same voltage rail.

If still not found, check the resistance to ground of each large coil / inductor. Note any very low resistance readings.

I found five more components heating up on the same setup. Aside from the U9400 which was initially detected heating up during voltage injection, there are five more parts that are heating up as well not that hot but the alcohol on top of them dried faster than other components and it is warm to the touch.

Components are : FL6500, FL6501, C6506, C6507 and U6500
Please see following image.

[Xenoaeuriix]

Re: MacBook Pro A1706 820-00239 no power

Here it is

[Xenoaeuriix]

Re: MacBook Pro A1706 820-00239 no power

Monitor who heats up. Does the regulator you have worked on heat up? Do also monitor the output side mosfets present on the same voltage rail.

Yes the U9400 still heats up, I am really sorry I don't know which of them is the mosfet nor how to do this "monitor the output side mosfets present on the same voltage rail."

[Xenoaeuriix]

Re: MacBook Pro A1706 820-00239 no power

I switch from using alcohol to rosin it clearly shows what is heating up. It is one of the capacitors near U9400 the C5910

[Xenoaeuriix]

Re: MacBook Pro A1706 820-00239 no power

Sorry the capacitor is C9401

[Xenoaeuriix]

Re: MacBook Pro A1706 820-00239 no power

I see that this is connected in parallel to the other capacitor that I knock out while trying to re-attach the fuse F7000

The red circle is what's heating up while the yellow is the one I knocked out.

[mon2]

Re: MacBook Pro A1706 820-00239 no power

Good. With flux and low air pressure, carefully remove this capacitor. After the part is off the board, allow it to cool and measure the resistance of this removed capacitor.

One meter lead on each side of the cap while it is on your work table.

Confirm again the resistance to ground of PPBUS_G3H with this cap off the logic board.

Do you still have a short?

The lost cap will not be missed. It is not critical to the operation of this logic board. Different cap values filter out different noise.

[Xenoaeuriix]

Re: MacBook Pro A1706 820-00239 no power

Doing it now, by the way U9400 is not actually heating ut at all, I just thought it is because I got burnt while touching it but it is because the capacitor that is heating up is too close to it.

[Xenoaeuriix]

Re: MacBook Pro A1706 820-00239 no power

One meter lead on each side of the cap while it is on your work table.
= The reading is 000.0 ohms

Confirm again the resistance to the ground of PPBUS_G3H with this cap off the logic board.
= short now is gone for the ppbus_g3h value keeps on changing start with 1.000M oHms and keeps going down to 0.786M oHms so I stop there. Should I wait for the reading to stop?

[mon2]

Re: MacBook Pro A1706 820-00239 no power

Very good.

In order,

1) apply back the resistors removed from the regulator. Check the resistance to ground again.

2) after all of the removed resistor parts are back on the logic board, check the resistance to ground again. It should remain high resistance.

3) if good, inject 1 volt again onto the downstream side of F7000 pcb pad. The current draw should not be peaking like before when you had a hard short. Confirm it.

4) if good, apply the fuse F7000 back onto the logic board. Measure the resistance to ground again. If not low, continue to power up with the known good power adapter. If all is well, you should have a valid PPBUS_G3H voltage at F7000.

Post your updates.

[Xenoaeuriix]

Re: MacBook Pro A1706 820-00239 no power

Thank you for the response. My shift already started almost an hour ago. I will be doing this later during my break which will be in 30 mins. I will keep you posted. Thanks!

[Xenoaeuriix]

Re: MacBook Pro A1706 820-00239 no power

Very good.

In order,

1) apply back the resistors removed from the regulator. Check the resistance to ground again.

2) after all of the removed resistor parts are back on the logic board, check the resistance to ground again. It should remain high resistance.

3) if good, inject 1 volt again onto the downstream side of F7000 pcb pad. The current draw should not be peaking like before when you had a hard short. Confirm it.

4) if good, apply the fuse F7000 back onto the logic board. Measure the resistance to ground again. If not low, continue to power up with the known good power adapter. If all is well, you should have a valid PPBUS_G3H voltage at F7000.

Post your updates.

1) Good resistance after adding back removed resistors.
2) Yes it is still showing high resistance.
3) Did the voltage inject, it is not drawing any current at all.
4) Fuse has been re-attached back. Measured resistance and it still showed high resistance like there was no short, to begin with. Powered up the board
PPBUS_G3H showing voltage now 13.X v looks running well now and the USB meter is showing good Amp reading. It looks like it is booting up now. Should I go ahead and put the board back in to test?

[mon2]

Re: MacBook Pro A1706 820-00239 no power

Excellent. Yes, proceed to place back into the enclosure for testing. Crossing fingers and other body parts.

[Xenoaeuriix]

Re: MacBook Pro A1706 820-00239 no power

It did boot up but instead of the usual welcome screen what I saw is a flashing folder with a question mark in it as if the disk cannot be detected by the laptop. I then run online recovery downloaded it and run reinstall macOS online. But then during the process, it cannot find the disk where it can be installed to. Also, I did try to run the disk utility and still cannot find the disk from there. I will try to boot my external disk to see if it can find the disk do you have any suggestions to fix it?

PS: Thank you so much for your patience and awesome guidance to help me get it fixed. I really appreciate it so much. This is the first ever laptop that I manage to revive after being dead for so long.