820 00165A .... 5v Missing

2informaticos

Administrator
Staff member
First of all, welcome to the forum!

Fluctuating how?
Do you get pulse every 2, or 5 seconds?
Or the voltage fluctuates continuosly?

What about 3v3_S5 (L7560), PPBUS_G3H and 3V42_G3H?
Post some useful information; any history available?
 
Ampere fluctuates between (38 amp to 110 amp)

PPBUS_G3H Present (8.6 V)
PP3V3_S5_REG_R Present (3.3)
PP3v42_G3H Present
PP5V_S4RS3 Missing (5V)

*After removing R7551

Pin 1 on R7551 P5VS4RS3_EN Present

Pin 2 on R7551 P5VS4RS3_EN fluctuates

PP5V_S4RS3 Present (5V)
 

2informaticos

Administrator
Staff member
"(38 amp to 110 amp)"
I hope you don't believe this; me NOT.
Make difference between A and mA!!!

Please, post accurate information.
Enable signal on R7551 pins, has different names; check schematic
"Pin 1 on R7551 P5VS4RS3_EN Present
Pin 2 on R7551 P5VS4RS3_EN fluctuates"
What we should understand from this???

"Fluctuating how?
Do you get pulse every 2, or 5 seconds?
Or the voltage fluctuates continuosly?"
Can we get a clear answer?

"any (fault) history available?"

Did you try starting in SMC bypass?
 
Yes, readings are in mA. MY BAD

Removed R7551

Pin 1 on R7551 P5VS4RS3_EN_R (Present 5V)

Pin 2 on R7551 P5VS4RS3_EN (Pulsing every 2 Second)

No history before

Can you help me with SMC Bypass? I didn't try. I am learning I am not perfect
 
Yes, readings are in mA. MY BAD

Removed R7551

Pin 1 on R7551 P5VS4RS3_EN_R (Present 5V)

Pin 2 on R7551 P5VS4RS3_EN (Pulsing every 2 Second)

No history before

SMC bypass? I keep the power button down and plug the charger in ,and then release the power button.....Fan Rotates for a sec and then turns oFF

NO Difference
 

2informaticos

Administrator
Staff member
If fan tries to spin, probably more voltages try to appear on the board.
Check for pulse at all big coils.
Also check pins 1, 3 & 7 of U1950.

Trigger SMC_ONOFF_L and check for pulse at mentioned points (at same time).

Inspect Q8150 and U1950 areas for corrosion.

If machine came from a client, didn't say anything?
 
I disconnected the L7430 from pin 2

Pin 2 ( PPDDR_S3_REG_R ) : 2 V on the coil

All coil voltages are stable

L7560 = 3.3 V
L7520 = 5V
L7630 = 1.05
L7430 = 2V (Pin 2 end of the coil is disconnected from the board)... This should be 1.2V, but I am getting 2V on Pin2 of the coil which is disconnected from the board. ANY Solutions?
 

2informaticos

Administrator
Staff member
I can't help in this way.
You've been asked to do same checkings on the board.

Very likely corrosion on Q8150, or U1950 areas.
Maybe some problems around U7400, god knows.
We need some accurate information.
 
Board looks clean to me ....I am checking under microscope

is it possible ? L7430 = 2V (Pin 2 end of the coil is disconnected from the board)... This should be 1.2V, but I am getting 2V on Pin2 of the coil which is disconnected from the board
 

2informaticos

Administrator
Staff member
How can you think to test a buck converter without its coil???

Let me know when you decide to post some useful information...
 
Sir, One end on the coil is connected on the coil and other end(PIN 2) is in the air.

Please ask your questions ,I will not touch it unless you ask me to do
 
Sir, One end of the coil is connected to the board and other end(PIN 2) is in the air.

Please ask your questions ,I will not touch it unless you ask me to do
 

2informaticos

Administrator
Staff member
Resolder ALL BACK on the board.

"Check for pulse at all big coils.
Also check pins 1, 3 & 7 of U1950.

Trigger SMC_ONOFF_L and check for pulse at mentioned points (at same time).

Inspect Q8150 and U1950 areas for corrosion."

No need to write double posts.
Please maintain forum aesthetic...
 
No corrosion detected near Q8150 and U1950 areas

Before trigger SMC_ON_OFF_L

U1950

pins 1: Pulsing

Pin 3: Pulsing

Pin 7: Pulsing


After trigger SMC_ON_OFF_L

U1950

pins 1: Pulsing

Pin 3: Pulsing

Pin 7: Pulsing
 

2informaticos

Administrator
Staff member
You didn't understand what trigger SMC_ONOFF_L means.

However, now remove Q8150 and test if get stable voltage on big coils (at least few of them).
 
SMC_ONOFF_L : It shorted together for a millisecond

Anyways..... I removed Q8150 and still the same situation

No stable voltage any other big coils

Only stable voltage on L7130 and L7560
 

2informaticos

Administrator
Staff member
"shorted together for a millisecond"
Yeah, but expected reaction must be checked at same time; in this milisecond!
Not before, nor after.

Keep Q8150 out of board.
Now remove R8164/65/66/68, one by one; keep R8167 on its place.
Tell us when (if) voltage appears on the coils.
 
Voltage is stable on all the coils

Current : 140 mA

L7130 =8.6V
L7520 = 5.1 V
L7560 = 3.3 V
L7430 = 1.2V
L7630 = 1.05V
L7320 =1.6V
L7310 =1.6V

But it is going in original state sometimes when I plug out and plug it back in to DC supply
 
Last edited:

2informaticos

Administrator
Staff member
I said to remove the mentioned resistors one by one and tell us when voltages come on.
Don't you want to help us to diagnose anything on this board???

"when I plug out and plug it back in to DC supply"
Are you using lab PSU, not original Magsafe 2 charger?
 
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