MacBook AIR A1466 820-00165-A - świeci pomarańczowa dioda, Grzeje się U1900

Dzień dobry,
MACBOOK AIR A1466 820-00165-A
Podłączenie zasilacza zaświeca pomarańczową diodę. Laptop nie reaguje na włącznik.
Grzeje się układ U1900
Czy na C1910 powinna być tak niska rezystancja wynosząca 1,62Ω ?
Sygnał PPVRTC_G3H na tym kondensatorze wynosi 0,336V

Znalazłem mały punkt z korozją w okolicach rezystora R8156 - ale wszystkie rezystory wydają się być sprawne.
PPV3V_S5 - na tym rezystorze 3,3V

U1900:
p1 - 0,33V
p5 - 3,31V

Czy U1900 jest do wymiany? Czy coś jeszcze sprawdzić?

Sasni ha scritto:Czy na C1910 powinna być tak niska rezystancja wynosząca 1,62Ω ?

Hello!
Not at all. That's a short circuit to ground and that's most likely also the reason of heating the chip U1900.
Perform a short circuit test described here on the power rail "PPVRTC_G3H".
For a short circuit test limit the voltage to 3V and do not exceed the current of 1A, otherwise there is a risk to burn the copper traces on the PCB.

The PCH part (small core) of the APU hybrid is unfortunately very likely damaged.

Thanks for your reply.
I did not perform a short-circuit test - earlier I found another corrosion and a shorted capacitor C0890 - it is on this suspicious line.
Now i have 3,3V on PPVRTC_G3H and laptop works when i disconnect tape between motherboard and small board with DC / USB / headphone jack.
When this tape is connected, i have an amber light and laptop wont turn on.

I found Signal PP3V3_S0 is gone when tape is connected. Now Should i Perform a short circuit test on this small board only?

Measure the resistance to ground on the power rail "PP3V3_S0" with and without small USB/Audio board connected.

The resistance does not change and is approximately 10kΩ
I noticed that I also don't have PP5V_S0 signals - I don't know if I should have them when the laptop is not running? The resistance on this line also does not change and is approximately 50kΩ
Connecting the power supply without a module simply turns on the laptop, so I take measurements with it running. However, when the board is disconnected, I measure it with it turned off.

USB_PVR_EN - connected - 0V / disconnected 3,3V

Sasni ha scritto:I noticed that I also don't have PP5V_S0 signals - I don't know if I should have them when the laptop is not running?

The voltage on this line should be present in "S0" state only (when the machine is turned on).

Inspect both sides of the small USB/Audio board under a microscope for signs of spilling or any other damage.

The board is marked 820-3455-A - unfortunately I do not have a diagram or boardview. I see many measurement points on the board that have discoloration. Is it normal?


The marked element has very low resistance, below 1Ω (~0,5Ω)

Sasni ha scritto:The marked element has very low resistance, below 1Ω (~0,5Ω)
[ Obrazek ]

This component is a coil, so the resistance is normal.

Measure the resistances to ground on pins 1, 3, 5, 7, 9, 11, 13, 19, 21, 23, 25, 27, 29, 39, 43, 45, 47 of connector J9500 with the small USB/Audio board connected to the motherboard.

Hi,
I decided that it would be faster and cheaper to buy a new module.
Unfortunately, I had the same symptom with the new board. The laptop does not start, and the orange LED on the power supply is on.
I don't repair Macbooks very often. I wanted to check if it was charging the battery, so I connected it (the battery) and the laptop started to boot. So it needs a battery connected - I didn't know about it.
The laptop appears to be working properly now. Thank you for your help.