Puzzler: A1707 unresponsive kbd, only boots with J6951 unplugged! I2C?

[Holes Flow]

Experts,

A1707 won't boot. UNLESS I unplug J6951 (and either push Tough ID or USB-C insert).... I'm guessing pin 2 or 3 shorted to gnd. BUT the keyboard is unresponsive no matter what, and they use J4500 & J4501...

Can these 2 be related? Does the I2C bus for keyboard also have battery signals (meaning if 1 shorted, they both fail)?

How can I test to see if the keyboard doesn't need to be replaced?



BIG thanks to anyone familiar, as non-LB schematics are non-existent.

P.S. Sure wish I could hook the scope up to these busses instead of needing 3-4 hands... maybe solder wires to PCB test points to clip on to like we used to do?)

...also attached the shot of the 2 connectors with kbd I2C

 

[MacInWin]

You are in the wrong place. This board does not really have any insight into the hardware at that level. Apple is very close to the chest with schematics, reserving them for a very few techs and all of those with severe NDAs about them. We here focus on software and configuration issues. If it gets to a hardware issue, our usual suggestion is to replace the board/system.

 

[Holes Flow]

Am I in the wrong place? Is there a better forum for troubleshooting logic board and operational issues on the MacBook pros?

If there's a better place on this board, I guess in a forum or a subform, then please direct me as I don't want to waste anyone's time if I'm posting in the wrong forum for this kind of problem.

 

[chscag]

Am I in the wrong place? Is there a better forum for troubleshooting logic board and operational issues on the MacBook pros?

You're welcome to post here anytime. But you might wish to post at iFixit: The Free Repair Manual. They have a community forum which is quite good along with a lot of tech savvy folks like yourself who participate. You do have to join though.

Good luck.

 

[MacInWin]

Am I in the wrong place? Is there a better forum for troubleshooting logic board and operational issues on the MacBook pros?

If there's a better place on this board, I guess in a forum or a subform, then please direct me as I don't want to waste anyone's time if I'm posting in the wrong forum for this kind of problem.

It's not that the forum is wrong but that the entire thrust of this particular board is not in the deep technical hardware arena. As chscag said, iFixit may be a better place to get the information you need. I doubt there are many here who can understand the question, much less provide the answer. We tend to help with software issues and hardware issues that can be resolved without resorting to on-board repairs. When we find that kind of hardware, we point people to Apple and Authorized Apple repair facilities. I just didn't want you to get frustrated because nobody responded to your inquiry. It's probably because we just don't know.

 

[Holes Flow]

OK, sorry to ask.

I was just hoping that the "Ultimate Source For Your Mac" was a little more ultimate...

I don't consider boards like the logic board as replaceable components, as I do the repairs AASPs can't, and Apple won't.

I now understand that this board/forums are not concerned with signalling and components, just software and replacing the big stuff.

Thanks for writing, @MacInWin & @chscag

 

[iggibar]

What kind of diagnostic testing have you done besides unplugging the keyboard?
Have you looked at boardview diagram to locate possible related components?
Have you looked at those components for continuity or shorts?
If that yields nothing, I would look at the components with an infrared camera heat detector when the computer turns on and after when it no longer turns on. There should be a component that heats up more than usual, and that will most likely be the part that needs replacing. This can also be done by using alcohol, but it will take MUCH longer to figure out which component is bad if you can't isolate the problem area.