• Macbook A2289 820-01987 no backlight

It is currently 14 December 2024, 04:27

Macbook A2289 820-01987 no backlight

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#1 Macbook A2289 820-01987 no backlight

by leonemax81 • 20 November 2024, 18:21
Ciao ragazzi mi capita questo macbook A2289 scheda madre 820-01987 che non accendeva, ho sostituito due componenti in corto U8110 e U7710, adesso il Macbook funziona ma non ha backlight, con monitor esterno funziona regolamente.

Ho sostituito anche il driver U8400 due volte senza successo, sostituito Q8400 senza successo.

EDP_BKLT_EN è presente fino a quando non appare il logo dopo scende a zero.

PPVOUT_S0_LCDBKLT_F non risulta in corto.

Re: Macbook A2289 820-01987 no backlight

by Google Adsense [BOT] • 20 November 2024, 18:21

#2 Re: Macbook A2289 820-01987 no backlight

by matic • 21 November 2024, 08:50
Hello!

Measure the voltage to ground on pin 2 of ferrite bead L8420 in both cases - when the signal "EDP_BKLT_EN" is at high (before the logo appears) and low level.

#3 Re: Macbook A2289 820-01987 no backlight

by leonemax81 • 21 November 2024, 18:43
matic wrote:Hello!

Measure the voltage to ground on pin 2 of ferrite bead L8420 in both cases - when the signal "EDP_BKLT_EN" is at high (before the logo appears) and low level.


always measures 0 volts.

#4 Re: Macbook A2289 820-01987 no backlight

by matic • 22 November 2024, 08:05
Check the fuse F8400 (3A, fast acting, package 0603).

#5 Re: Macbook A2289 820-01987 no backlight

by leonemax81 • 22 November 2024, 13:22
matic wrote:F8400


già controllato fusibile F8400 buono.

#6 Re: Macbook A2289 820-01987 no backlight

by matic • 22 November 2024, 17:12
Measure the voltages to ground on pins 5, 9, 10, 11, 15, 16, 17, 18, 21 of chip U8400.

#7 Re: Macbook A2289 820-01987 no backlight

by leonemax81 • 22 November 2024, 19:37
matic wrote:Misurare le tensioni verso terra sui pin 5, 9, 10, 11, 15, 16, 17, 18, 21 del chip U8400.


PIN 5: 5 VOLT.
PIN 9: 12.6 VOLT.
PIN 10: 12.6 VOLT.
PIN 11: 12.4 VOLT.
PIN 15 E 16: 3.3 VOLT.
PIN 17: 3.3 VOLT. POI SCENDE A ZERO APPENA APPARE IL LOGO APPLE.
PIN 18: 5 VOLT.
PIN 21: 0 VOLT.

aggiungo anche che ho provato a collegare un monitor di un'altro modello di macbook 15" A1707 e il logo si vede bene illuminato, PPVOUT_S0_LCDBKLT_F sale fino a 50 volt, poi appena entra in scrivania la retroilluminazione si abbassa al minimo.

#8 Re: Macbook A2289 820-01987 no backlight

by matic • 27 November 2024, 10:59
leonemax81 wrote:provato a collegare un monitor di un'altro modello di macbook 15" A1707 e il logo si vede bene illuminato, PPVOUT_S0_LCDBKLT_F sale fino a 50 volt, poi appena entra in scrivania la retroilluminazione si abbassa al minimo.
The backlight of your original screen is very likely damaged. Replace the screen.

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