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A1534 no power

H

hgoncalves

Active member
Hello,

I have an A1534 that had water damages, and has been ultra-sonic cleaned in other store.
Now it doesn't power on.

It has 4.98V on charger and pulls 0.02A.

In PPBUS_G3H i have 0V and on F4700 i have 5V.

Can you help me?
 
2informaticos

2informaticos

Administrator
Staff member
Ultrasonic cleaner can make more damage, if not correctly used.
Sweep function is a must, to avoid hot spots in the process.
Check for knocked off components and broken traces.

Be sure no short on any power rail.

Can we know what board do you have?
Is a must when ask for help.
 
H

hgoncalves

Active member
Sorry, the board is an 820-00045.
I can't see any broken traces, but It seams that i have a missing SW6900, and the U4490.
I have a short in PP3V3R3V0_AON and in E85LSMUX_RFU_EN_L i have 0.99 ohm resistance
 
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2informaticos

2informaticos

Administrator
Staff member
U4700/80 are the first suspects there.
But more chips are connected on 3V3_AON.

Short on E85LSMUX_RFU_EN_L points more to U4470/90.
Pray that is not U4600...
 
H

hgoncalves

Active member
Hello again.
It seams that the U4600 is shorted. It is the only thing that gets hoted when injected 2.5V with 3A in 3V3_AON (already taked out the U4700/80 )
Is it possible to replace the U4600?
 
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H

hgoncalves

Active member
OK. I´ve changed the U4600, and reballed the U4700/80. The shorts are gone ( 3V3_AON and E85LSMUX_RFU_EN_L ) but still no boot ( It has 4.98V on charger and pulls 0.02 A).
 
2informaticos

2informaticos

Administrator
Staff member
Other chips from 3V3_AON can be damaged.
Even there is no short anymore.
0.341 still looks low; U4700 is the first suspect...
 
H

hgoncalves

Active member
On pad 1of the board, of the U4700 i have 0.339 but all other pins are arround 0.500 / 600. this maybe means that the problem is before the U4700, don't you think? Am i understanding this wrong?
 
H

hgoncalves

Active member
Hello again,
I've replaced U4780 and now thr 3V3_AON its also 0.331 in diode reading, but It is pulling 19.5V but only consumes 0.2A on ampmeter
 
2informaticos

2informaticos

Administrator
Staff member
Diode mode should be higher than 0.400 I think.
Compare with working board.
Seems that still a bad chip on 3V3_AON...
 
H

hgoncalves

Active member
I don't have any working board. Is there any other way?
On 2 other boards (parts) the value is near the same. In this board, on 3V3_AON i have 3.28V
 
2informaticos

2informaticos

Administrator
Staff member
You've got 3V3 after changed U4600.
It was damaged by overvoltage on 3V3_AON.
Something else must be affected, even not shorted to ground.

"U4700 on the 12" A1534 Retina Macbook from the year 2015 is SLG4AP645AV.
This is the most common cause of a 6-400 ohm low value on the PP3V3R3V0_AON power rail."
This is an old note from dukefawks; so even 400 is lower value than normal...
 
H

hgoncalves

Active member
Good morning,

I've replace the U4700 with a new one, but the same result. On U4700 i have, on BBPD_RPD_EN (PIN 17) 3.2V and on BBPD_VCONN_EN 0V, but on BBPD_VCONN1_EN and BBPD_VCONN2_EN (Pins 5 and 8) i have 0V.

Now i notated that the power cable only works in one position. If if flip the cable, it doesn' t work.

Is this relevant?
 
H

hgoncalves

Active member
I've replaced U7860/65 and the behaviour is the same.
Diode readings on U4700 of pin 10 is 0.530, and on pin 12 it is 0.546.
With power connected i have on pin10 0V and on pin 12 0.850V.

Is this helpless? do you think i should give up on it?
 
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