820-00281 Won't turn on

punkieftw

New member
Hi, i have a Macbook Pro Retina Touchbar 15" , No water damage, No corrosion visible, board looks pretty well, but not turning on.

On the USB-C measure tool, gets 5v - 0.0 amps for a second, them try to get some more power and up to 0.03 and the USB-C PowerMeter get off and on again on a infinite loop.

I measure this:

PPBUS_G3H - 0.0017v
PP3V3_G3H - 3.34v (For a 3-4 secs and them gets down for a sec or less and gets again up)
PPDCIN_G3H_CHGR 5.21v (For a 5-6 Secs and them gets down around 1.2v for a sec or less and gets again 5.21v)

I really don't know where looks first, so many rails and signals are new in this boards and i don't know who must be present first.

Any help?

Thanks in advance.
 

2informaticos

Administrator
Staff member
USB-C controllers seem to be OK.
If board tries to start every 5s, means SMC talks with charger, but detects some error and power goes down.
Does it start in SMC bypass mode?
Check for short, or low resistance to ground on all coils; and F7000/01 too.
 

JohnB8812

New member
Bootlooping on all of the ports or just one? Could be an issue with one of the CD3215s. Definitely no corrosion near any of them?
 

punkieftw

New member
USB-C controllers seem to be OK.
If board tries to start every 5s, means SMC talks with charger, but detects some error and power goes down.
Does it start in SMC bypass mode?
Check for short, or low resistance to ground on all coils; and F7000/01 too.
Resistance to ground on these coils its about 10 milliohms (10M?), how i can test bypassing the SMC? like an old macbooks?
 

2informaticos

Administrator
Staff member
"Resistance to ground on these coils its about 10 milliohms (10M?)"
First, which coils?
I didn't mention any; F7000/01 are fuses from PPBUS_G3H.
Second, M on DMM display means Megohms...

Measure on diode mode, red probe to ground; disconnect any power first.
Start checking on PPBUS_G3H.

If 5V goes off every 5s, is because the board try to start and some sensor error forces SMC to restart it.
Starting in SMC bypass can confirm/discard that.

BTW, do not quote an entire previous post; is not aesthetic.
Quote only the text you want to refer.
 

JohnB8812

New member
If PPDCIN is only getting to 5 volts, something is pulling it down usually one of the CD3215 chips. Inject 3.3 volts on PP3v3_G3H and see if there is any current consumption. If so, use freeze spray or alcohol or whatever to see if one of the CD3215s is causing it. In my experience, the one that often fails is U3200, but it could be any of them!
 

2informaticos

Administrator
Staff member
The board gets only 5V as normal in the first moment.
After SMC talks with the charger, voltage should go high, to nominal value.
In your case seems the voltage drops just in that moment.
This makes me suppose SMC talks with charger and ask it for nominal voltage; that is not possible if one CD3215 is bad.
The issue should be after U7000.

"Measure on diode mode, red probe to ground; disconnect any power first.
Start checking on PPBUS_G3H."
 

punkieftw

New member
"Resistance to ground on these coils its about 10 milliohms (10M?)"
First, which coils?
I didn't mention any; F7000/01 are fuses from PPBUS_G3H.
Second, M on DMM display means Megohms...

Measure on diode mode, red probe to ground; disconnect any power first.
Start checking on PPBUS_G3H.

If 5V goes off every 5s, is because the board try to start and some sensor error forces SMC to restart it.
Starting in SMC bypass can confirm/discard that.

BTW, do not quote an entire previous post; is not aesthetic.
Quote only the text you want to refer.
Ok my mistake, i mean fuses, on these fuses. And, i take a picture for you of my measures on the fuses so you let me know the resistance, i think this is milliohms.

So, i do the SMC Bypass too and stuck on 5.21v - 0.00 A on the meter on all USB-C Ports.

Any other idea?

Thanks !
 

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punkieftw

New member
The board gets only 5V as normal in the first moment.
After SMC talks with the charger, voltage should go high, to nominal value.
In your case seems the voltage drops just in that moment.
This makes me suppose SMC talks with charger and ask it for nominal voltage; that is not possible if one CD3215 is bad.
The issue should be after U7000.

"Measure on diode mode, red probe to ground; disconnect any power first.
Start checking on PPBUS_G3H."
What i need measure in diode mode? what i looking for?
 

2informaticos

Administrator
Staff member
In the photo you have Megohm value....
Select diode mode for the future.
However, not needed now; as you don't have low value.
Check for any voltage pulse at F7000.
An o-scope will help better, to catch the pulse level.
If get something, check if other coils pulses too.
Any pulse at any PM_SLP_S5/4/3_L, or PM_SLP_SUS_L?
 

punkieftw

New member
In the photo you have Megohm value....
Select diode mode for the future.
However, not needed now; as you don't have low value.
Check for any voltage pulse at F7000.
An o-scope will help better, to catch the pulse level.
If get something, check if other coils pulses too.
Any pulse at any PM_SLP_S5/4/3_L, or PM_SLP_SUS_L?
Hi again, no pulse on those signals, going crazy now.

I don't know if i think right but, these seems like a short to ground in any level, but i don't know where to look.

Help please!
 

2informaticos

Administrator
Staff member
Check resistance to ground (diode mode) on all coils.

PLEASE, quote only text lines wich you want to refer.
Maintain good aesthetic of forum...
 

punkieftw

New member
Ok, here is the measure of all single coils on the board in ohms. If any measure go to ohms scale i will take diode mode in this too. here we go..

L2959: 1.3k on both sides.

L3500: starts in 20k and goes down slowly and when get 15k get more slowly.

L6900: 120k and slowly goes down

LA900: 4.2k on both sides.

L9360: 0.9k on both sides.

L9370: 3.7k on both sides.

L9380: 5.5M and goes down slowly.

L9330: 8.7k on both sides.

LB150: 1.1k on both sides.

LB700: 14k on both sides.

LA350: 32 ohms on both sides and diode mode (Positive probe to ground) has 0.020.

LA650: 3 ohms on both sides and diode mode (Positive probe to ground) has 0.002. Very similar measures on "LA640 - L7330 - L7231 - L7221 - L7211 - L7420 - L7410"

L7030: 1.1M and goes down slowly.

L8000: 65.5 ohms on both sides and diode mode (Positive probe to ground) has 0.029.

L7960: 22.0 ohms on both side and diode mode (Positive probe to ground) has 0.013.

L7900: 140.5 ohms on both side and diode mode (Positive probe to ground) has 0.098.

L7660: 30k on both sides.

L7600: 44k on both sides.

L8410: 190k on both sides.

Have another 4 coils "L6400 - L6401 - L6450 - L6451" But this is for speaker and all of these have values on the kohms scale.

i hope this help you to help me. :)

Thanks!
 

2informaticos

Administrator
Staff member
Always start checking in diode mode.
Only switch to ohm mode for very low value; i.e. under 010 diode mode indication.

5V at R7020 drops every 5 seconds?
Do you have an oscilloscope for checking?
Sometime pulses to the coils, or other signal, are very short and DMM cannot catch them.
Check if PM_SLP_S5_L, or PM_SLP_S4_L get a pulse just before 5V drops.
Also monitor PM_SLP_SUS_L.
 

punkieftw

New member
Hi again!

Only switch to ohm mode for very low value; i.e. under 010 diode mode indication.
Ok, copy that.

5V at R7020 drops every 5 seconds?
https://vimeo.com/314606111

There is a video for that measure.

Do you have an oscilloscope for checking?
Sometime pulses to the coils, or other signal, are very short and DMM cannot catch them.
Check if PM_SLP_S5_L, or PM_SLP_S4_L get a pulse just before 5V drops.
Also monitor PM_SLP_SUS_L.
Yes i have an oscilloscope, i try to catch any pulse but i get nothing.

Any ideas?
 
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