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A1990 820-01041-A No Power

K

kashitozu

Member
Hello,

I have a MacBook a1990 who is blocking on 5v, we have change UB300 because i see on th thermal camera is go up to 50° degres but is no go on 20V.

After i have find a short ciruit on the line PP3V3_G3H_T, i have inject eletric power and i have find C8250 dead.

there is no more short circuit and the value of the diodes is normaly (423 Ohm) but i don't have the 3V3.

On J3300 when i plug usb-c i have 5V and 0.018A in the top connector and 20V and 0.000A in the bottom connector

But for JB500 is reverse, 20V and 0.000A in the top connector and 5V and 0.018A in the bottom connector.

The client give me the macbook with 5V only.
 
2informaticos

2informaticos

Administrator
Staff member
The mentioned tests, have been done with battery connected too?

Get a battery which holds some charge and test if board turns on.
If yes, your problem resides on USB-C area,
If not, may be anywhere else; a problem on USB-C persists anyway.
 
2informaticos

2informaticos

Administrator
Staff member
Sorry, I meant 3V3_G3H_RTC.

Anyway, PPBUS_G3H must appear first.
But U7000 can generate it with just 5V input.
Do you get R7020 voltage from all ports?
 
K

kashitozu

Member
For the USB-C ports on the left and right sides, the top USB sometimes stays stuck on 5V or 20V as before, and the bottom USB stays on 5V, but I have the 3V3 on the 3V3_G3H_RTC and the 5V on the R7020.
And when I have the 20V, I have no current going to the 3V3_G3H_RTC and the R7020.

Conclusions When I have 5V I have 3V3_G3H_RTC and I have 5V on R7020 but the 5V doesn't transform into 20V
When I have 20v I don't have 3V3_G3H_RTC and 0v on R7020
 
2informaticos

2informaticos

Administrator
Staff member
Instead of top/bottom, use corresponding CD3217 code to identify the channel.

Did you try original 87W charger?
Test the board alone on the desk, without battery connected.
 
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