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Macbook Pro 13" A1708 (820-00840-A) No image https://vlab.su/viewtopic.php?f=51&t=90197 |
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andromedax [ 16 май 2019, 20:36 ] | |
Заголовок сообщения: | Macbook Pro 13" A1708 (820-00840-A) No image |
Hi, another weird problem with a macbook. I'm trying to repair this Macbook Pro 13" A1708, (820-00840-A) it has no image, but backligth is working ok. All voltages are good, but has no vcore. L7410, L7420 and L7430 have voltage (cpu vcore) but only for half a second. The weird thing is that cpu gets hot, and fan spins. (also osx pendrive install usb, blinks as it were booting from it) Someone experienced something like this? Could be a damaged cpu or bios corrupted? Thanks in advance. |
Shooter75 [ 17 май 2019, 09:02 ] | |
Заголовок сообщения: | Re: Macbook Pro 13" A1708 (820-00840-A) No image |
Can You connect external display? |
andromedax [ 17 май 2019, 09:49 ] | |
Заголовок сообщения: | Re: Macbook Pro 13" A1708 (820-00840-A) No image |
Hi Shooter75, yes I can connect an external display whith usb-c to hdmi adapter but there is no image via external. The point is that without cpu vcore is not possible to guet video, but there is a normal voltage there (at the vcore coils) for a moment. Thanks for your help. |
Shooter75 [ 17 май 2019, 11:20 ] | |
Заголовок сообщения: | Re: Macbook Pro 13" A1708 (820-00840-A) No image |
If video-drain wasn't found at init-algorithm, vcore dosn't appear. |
andromedax [ 17 май 2019, 12:33 ] | |
Заголовок сообщения: | Re: Macbook Pro 13" A1708 (820-00840-A) No image |
Hi Shooter75, what do you mean with "video-drain". Could you explain it? Wich part of the circuit? Thanks. |
Shooter75 [ 17 май 2019, 15:39 ] | |
Заголовок сообщения: | Re: Macbook Pro 13" A1708 (820-00840-A) No image |
Do You understand "video-source"? Video-drain is antipod of. Wow - Any external/internal display. Without any V-D, vcore don't appear. 1. Verify AUX ch at eDP on MB. 2. If no detection packets appears - GT2.eDP channel is damaged. 3. And measure eDP-mux(TB-host), if it has it's power when You connecting external display. 4. If You have same situation with AUX ch at TB-host, - Your GT2 is damaged. You can backup Your original EFI and try any from 00840 with cleared ME. This will not to be stable, but You can detect efi-crashes. |
andromedax [ 17 май 2019, 19:37 ] | |
Заголовок сообщения: | Re: Macbook Pro 13" A1708 (820-00840-A) No image |
Shooter75 Цитата: Do You understand "video-source"? Yea, it is clear for me now. I'm going to test the communication with lcd panel and will post the results. Thanks again. [size=85]Posted after 3 hours 27 minutes 32 seconds:[/size] Цитата: Verify AUX ch at eDP on MB. Hi, I have measured EDP_INT_AUX_N signal and EDP_INT_AUX_N, and both have a burst of pulses in the boot process. Probably these pulses don't get its destination to lcd, so I'm going to order the flex cable and test again. I have also measured pwm circuits for PPVCCGT_S0G voltage, and only get pulses for a moment at pin 1 of coil L7410. Pin 1 of L7420 and L7430 has nothing. If the new flex video cable doesn't solve the problem, I will investigate if there is a problem with phase 2 and phase 3 of PPVCCGT_S0G pwm circuit. Thanks and hope to have good news soon. |
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