• iMac Mid 2010 27" A1312 820-2901-A Brak obrazu

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#1 iMac Mid 2010 27" A1312 820-2901-A Brak obrazu


by kamil1986 6 May 2022, 21:59
Komputer iMac Mid 2010 27" A1312 820-2901-A objawy brak obrazu na matrycy, usterka pojawiła się po zaniku zasilania w sieci. Gdy zasilanie powróciło komputer można uruchomić ale nie pojawia się obraz na matrycy. Komputer można wyłączyć przytrzymując włącznik jedyna zmiana jaka następuję to komputer jest włączony z odpiętą matrycą to wentylator od CPU pi około 20sek wchodzi na pełne obroty. Podmieniłem RAM oraz przeprogramowałem bios bez zmian. Niestety nie mam CPU na podmianę ale po uruchomieniu komputera z podłączoną matrycą CPU robi się lekko ciepły, a dokładnie płyta główna pod CPU ale to o niczym nie świadczy. Sygnały ALL_SYS-PWRGD, ALL_SYS-PWRGD_R, ALL_SYS-PWRGD_SMC obecne.

Moje podejrzenia padają na zasilanie matrycy brak napięcia PP12V_LCD_CONN. Z informacji jakie udało mi się znaleźć to to napięcie powinno się pojawić nawet z odpiętą matrycą. U mnie wynosi 260mV.

Re: iMac Mid 2010 27" A1312 820-2901-A Brak obrazu


by Google Adsense [BOT] 6 May 2022, 21:59

#2 Re: iMac Mid 2010 27" A1312 820-2901-A Brak obrazu


by matic 7 May 2022, 09:43
Hello!

- Measure the resistance to ground on pin 1 of transistor Q9000 with the LCD screen (matrix) connected.
- Measure the voltages to ground on pins 1, 3 of transistor Q9001, when the machine is turned on with matrix connected.
Transistor Q9001 pin count:
Image

#3 Re: iMac Mid 2010 27" A1312 820-2901-A Brak obrazu


by kamil1986 7 May 2022, 17:07
Hello Matic

- Measure the resistance to ground on pin 1 of transistor Q9000 with the LCD screen (matrix) connected.

At the beginning of measurement was 5kΩ and slowly increased and stabilize at 58kΩ
- Measure the voltages to ground on pins 1, 3 of transistor Q9001, when the machine is turned on with matrix connected

Pin.1 - 0V
Pin.3 - 11,82V

#4 Re: iMac Mid 2010 27" A1312 820-2901-A Brak obrazu


by matic 19 May 2022, 11:22
Check, if the picture is present on external monitor via DisplayPort.
You will probably need a Mini DisplayPort to VGA or similar adapter to connect the external monitor.
Image

#5 Re: iMac Mid 2010 27" A1312 820-2901-A Brak obrazu


by kamil1986 19 May 2022, 19:09
Hi Matic, the picture does not present on the external monitor. Also, the led light LED604 GPU_PRESENT is off. In my opinion, the GPU is damaged.

Re: iMac Mid 2010 27" A1312 820-2901-A Brak obrazu


by Google Adsense [BOT] 19 May 2022, 19:09
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