A1706 no power

[2informaticos]

So USB-C meter switches to 20V on all ports (w/ and w/o battery connected)?

Be sure to use 87/96W charger.
This board may not start with 61W charger.
Just in case, try starting in SMC bypass mode.

 

[students_t]

With no battery, all ports show same value; images for other three ports are attached.

 

[students_t]

When I connect the battery (assuming I have adequately reconnected the board, which is not certain), I get the same value on all four ports, but this is with the charger plugged in (not sure if that's correct or not). When the charger is not plugged in, meter does not turn on.

 

[students_t]

Here is the board partly back in the case. Non-reconnected things are circled; is it in an adequate state for doing the "with battery" checks you asked for?

 

[2informaticos]

Connected battery means tighten screw and also battery data cable.
And of course charger connected.

 

[students_t]

Ok, I made sure that the screw for the battery contact was tight and that the battery data cable was correctly connected. I think they were in an appropriate state when I check the "with battery" conditions before; when I check the meter again in this latest state I get all the same readings. Where to from here?

 

[2informaticos]

Do you get 3V3_S5 (L7660)?

 

[students_t]

With battery and charger connected, I get 3.36 V for 3V3_S5 measured at L7660. EDIT: Actually, possible correction (?) - I get the 3.36 V reading with red probe touching "North side" (relative to orientation in attached image from board viewer) but 0 V when touching the "South side" of the "box" on the board. So maybe the correct answer is 0 V. EDIT2: Just realized when I went back to check the "South side" voltage" I did not have the charger plugged in. It gives 3.36 V there, too.

 

[students_t]

Here's an image clarifying what I mean.

 

[2informaticos]

Please, do NOT use use cardinal signs here.
I hope the motherboard ground is clear for you.
No matter where to ground connect the black probe; there are thousand (igual) points, or more.
But ALWAYS connect red probe on the power rail, or signal, where you need to check; there are also many test points to use.
I said L7660, but you can connect to any other 3V3_S5 point...

Do you get voltage on any other big coil?

 

[2informaticos]

You picture has wrong notations.
You can't get different voltage to ground on the pins of the coil!

 

[students_t]

You picture has wrong notations.
You can't get different voltage to ground on the pins of the coil!

Yes, I forgot I had unplugged the charger when I went to check the other side; I made an edit but you were very quick in responding, which I appreciate, but I'm sorry I wasn't quite fast enough to save you some trouble!

Re: Cardinal directions. Understood. Sorry about that.

 

[students_t]

Do you get voltage on any other big coil?

Yes, for example I get 13.11 V at L7030. Should I check and report the voltage of all inductors, or was this just a spot check to set me straight when I was incorrectly claiming 0 V in once place?

 

[2informaticos]

L7030 was the less expected to check.
Try checking other coils...

 

[students_t]

Doing a check of voltages at all inductors of at least the size of L7660 on the same face of the board, I only get readings at L7030 (13.11 V).

Although a reading of 3.36 V was previously observed at L7660, now I am getting 0 V. One measurement made sometime after getting the initial 3.36 V value, I observed a seemingly consistent 0.22 V value at L7660 (I got this reading on both sides of the unit—just changing sides to make sure I had made good contact). But now I just get 0 V at L7660. I still get 3.44 V at L6900, 13.12 V at F7000 (PPBUS_G3H), and 13.11 V at L7030, so the change of L7660 to 0 V is not a consequence of something dumb like no power cord or bad ground contact (well, maybe a consequence of something dumb I am unaware of currently...).

 

[2informaticos]

Do you work with the board alone on the desk?
Are you using 87W charger?

Now post diode mode readings on all big coils.

 

[students_t]

Do you work with the board alone on the desk?

Ever since you asked for checks with the battery connected, I have had the board partially back in the case. For the diode tests you just requested I will take the board back out of the case. Basically all I am doing at this desk/workspace is working on the computer, so I think the answer is "yes, I work with the board alone on the desk"... is there something you think I might have here that I shouldn't?

Are you using 87W charger?

Yes, I am using the one that came with the laptop, and I was using it at the moment that the laptop died, BUT I think it is possibly noteworthy that within, say, 48 hours before the laptop died I was using two different chargers: (1) one was a colleagues charger for a (I think) comparable macbook that had a terribly frayed cord (so much so that after trying to use it for a little bit I gave up and went to get mine from a somewhat remote location); (2) another was a charger I had gotten off Amazon that I basically never use (outside the 48 h period there have been maybe one or two other times that I have used it).

Now post diode mode readings on all big coils.

Working on that right now.

 

[students_t]

COIL	DIODE MODE READING (in dV I guess)
L3500	0.172
L8410	1.036
L7030	0.269
L6900	0.334
L7600	0.392
L7660	0.325
L7700	0.241
L7430	0.005 (and my particular multimeter beeps—I'm sorry, I'm pretty new to this...)
L7420	0.005 (also beeps)
L7410	0.005 (beeps)
L7210	0.012 (beeps)
L7220	0.012 (beeps)
L7270	0.018 (beeps)
L8050	0.272
L7900	0.204
L8000	0.231
L7960	0.120
LB700	0.158
L9400	0.329

 

[2informaticos]

You should check the charger power.
Chinese chargers may trick you; marking power may be not true.
Checking the power reported by another machine into system report is the best way.
And I recommend to use ALWAYS original Apple chargers.

This board should turn on automatically, out of case (alone on the desk), with 61/87W charger.
Don't put the MLB back in the case, until is repaired; unless you give up.

The diode mode values listed look good.

Are you sure no voltage at L7660?

Check PMIC LDOs at page 74; U7800 (7 OF 10).

 

[students_t]

Are you sure no voltage at L7660?

Correct, still no voltage at L7660—I have just now checked again; the board is out of the case, connected to the charger, and not connected to the battery; when I check voltage at other locations in this current configuration I do get readings (e.g., L7030 is still giving 13.11 V).

Check PMIC LDOs at page 74; U7800 (7 OF 10).

Position	Voltage (V)
C7833 (LDO3V, PP3V_PMICLDO)	3.32
C7836 (LDO5V, PP5V_PMICLDO)	0.08
C7837 (VINLDO3, PPBUS_PMIC)	13.10
R7866 (VDD5_VPROGOTP, PP5V_PMICLDO_R), C7831 (VDD5_VPROGOTP, PP5V_PMICLDO)	0.08
C7830 (VDDIO0, PP3V3_PMICLDO)	3.31