#1 Macbook Pro 13" A1502 motherboard 820-3476A Orange led no power on
Napisal/-a valieromarco • 26 December 2025, 03:03
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- Naslov teme mora vsebovati: proizvajalca naprave, poln model in kratek opis okvare.
- Sporočilo teme mora vsebovati: oznako tiskanega vezja (v primeru popravil strojne opreme), razširjen opis okvare, kaj je bilo preverjeno, zamenjano in/ali izmerjeno, sklep in vprašanje. Če ne morete najti oznake tiskanega vezja, morate prebrati TO TEMO. Če še vedno ne najdete oznake, prosim objavite kakovostne fotografije obeh strani matične plošče - potrebno je odstraniti vse folije in module, ki bi lahko zakrivali te oznake.
- Pred objavo nove teme, preberite vse teme v podforumu USPOSABLJANJA, in naredite predhodno diagnostiko na podlagi vsebine teh usposabljanj.
- Nalaganje celotnih navodil/shem, BIOS / firmware datotek, ali objavljanje povezav, ki vodijo do drugih spletnih strani s takšnimi datotekami, je SROGO PREPOVEDANO. Lahko objavite le majhen del navodil/shem, ali povezavo na BIOS datoteko v podforumu NEVERIFICIRANE DATOTEKE BIOS/EFI. V eni temi ne smete objaviti več kot eno stran navodil/shem. Datoteka ne sme vsebovati vidnih žigov "zaupno",, e-poštnih naslovov ipd.
- V eni temi lahko opišete SAMO eno napravo. Za vsako drugo okvarjeno napravo morate odpreti novo temo.
- Zahteve za sheme, boardview, fotografije matičnih plošč, datoteke BIOS-a ali servisne priročnike za storitve NISO DOVOLJENE. Če želite vprašati za katero koli od teh, odprite novo temo v podforumu ZAHTEVA ZA DOKUMENTACIJO & DATOTEKO BIOS/EFI.
Re: Macbook Pro 13" A1502 motherboard 820-3476A Orange led no power on
Napisal/-a Google Adsense [BOT] • 26 December 2025, 03:03
#2 Re: Macbook Pro 13" A1502 motherboard 820-3476A Orange led no power on
Napisal/-a Vogelek23 • 26 December 2025, 05:31
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#3 Re: Macbook Pro 13" A1502 motherboard 820-3476A Orange led no power on
Napisal/-a valieromarco • 26 December 2025, 14:43
After solder old chip nothing is changed but I saw that a resistor was missing and now I got up and down voltage on both coils L7520 and 7560 fro 0V to 0,5V
I checked pin + of battery connector is 12,5V but after 3 seconds drops to 4V for 3 seconds and goes back to 12,5V continuously
Voltages of U7501
1=0V
2=0V
3=0V
4=5V
5=0V
6=5,1V
7=0V
8=0V
9=0V
10=4,8V
12=3,42V
13=5,1V
14=5,1V
15=4,8V
16=0V
17=0V
18=0V
19=5,1V
20=0V
21=3,42V
22=3,9V
23=12,5V
24=0V
25=0V
26=5V
27= 0V
29=5,1V
30=0V
31=5V
32=0V
I checked pin + of battery connector is 12,5V but after 3 seconds drops to 4V for 3 seconds and goes back to 12,5V continuously
Voltages of U7501
1=0V
2=0V
3=0V
4=5V
5=0V
6=5,1V
7=0V
8=0V
9=0V
10=4,8V
12=3,42V
13=5,1V
14=5,1V
15=4,8V
16=0V
17=0V
18=0V
19=5,1V
20=0V
21=3,42V
22=3,9V
23=12,5V
24=0V
25=0V
26=5V
27= 0V
29=5,1V
30=0V
31=5V
32=0V
#4 Re: Macbook Pro 13" A1502 motherboard 820-3476A Orange led no power on
Napisal/-a ado • 26 December 2025, 20:02
Start by measuring the resistance to ground on PP3V3_S5. PP5V_S4/
Your initial decision to replace U7501 seems reasonable. Since EN is present, it confirms that SMC is alive and has allowed the power-up sequence, which is a good sign.
However, there may still be a short or abnormal load downstream of the PMIC. The rather abrupt reaction after the replacement suggests that U7501 could be shutting itself down due to protection mechanisms, such as OCP or OVP, rather than a control or firmware issue.
Edit Ai:
In Apple boards, standby lines like PP3V3_G3H are always live, but 5 V rails tend to be more vulnerable to shorts from I/O, USB, or other peripherals. Check these rails carefully before concluding that U7501 is faulty.
Your initial decision to replace U7501 seems reasonable. Since EN is present, it confirms that SMC is alive and has allowed the power-up sequence, which is a good sign.
However, there may still be a short or abnormal load downstream of the PMIC. The rather abrupt reaction after the replacement suggests that U7501 could be shutting itself down due to protection mechanisms, such as OCP or OVP, rather than a control or firmware issue.
Edit Ai:
In Apple boards, standby lines like PP3V3_G3H are always live, but 5 V rails tend to be more vulnerable to shorts from I/O, USB, or other peripherals. Check these rails carefully before concluding that U7501 is faulty.
#5 Re: Macbook Pro 13" A1502 motherboard 820-3476A Orange led no power on [REŠENO]
Napisal/-a valieromarco • 27 December 2025, 02:45
Re: Macbook Pro 13" A1502 motherboard 820-3476A Orange led no power on [REŠENO]
Napisal/-a Google Adsense [BOT] • 27 December 2025, 02:45
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