A1398 - 820-3662-A shutdown with battery

[hgoncalves]

Hi,

I have an A1398 - 820-3662-A, that when with the battery connected, and even with the charged connected, it shutsdown after a few minutes powered on.

With the battery disconnected, it works fine four days without shutting down, even playing FHD videos for days.

Already replaced with a known good battery, with the same result.

Idon't know where to start.

Can you help?

 

[2informaticos]

Tested in safe mode?
Any error pops up in diagnostic mode?

I suspect the classic FDMF6808 problem.
Try the software trick for that...

 

[hgoncalves]

Hi,

In safe mode it works fine, and the diagnostic mode doesn't show any erros.

I only have FDMF6808 from donor boards, and I read that it isen't a good idea replacing those for used ones...

I don't know the software trick. Can you point me to some documentation or videos explaining it?

Tks.

 

[2informaticos]

https://www.reddit.com/r/mac/comments/9pyort

 

[hgoncalves]

Hi.

After replacing all FDMF6808 for new ones, now I don't have internal image; only external image.

Already tried a known good display.

Can you help?

 

[2informaticos]

"new ones"
Bought from?

What is the voltage at pins 28-30 & 9 of J8300?

 

[hgoncalves]

Hi,

I've bought FDM6708N from Mouser

J8300
PIN 9 = 2.857V
PINs 28-30 = 5V

PIN 1 = 0V

 

[2informaticos]

Check for knocked off components, related with J8300 lines.
Are you sure image is missing too, or just backlight?

 

[hgoncalves]

Hi.

I'm not sure. However I've already U7750 and still no BL or image, and i have none knocked out components.

How can I be sure, of both (image and bl)?