820-00165 A1466 full fan-spin, no display, chime or back-light after repair attempt.

[EthanL1234]

Hello everybody!

Okay, so I should start this off by saying I am VERY new at this. I recently bought an A1466 MacBook Air on eBay to try and fix. When I got it, it powered on ONCE. It booted to the question mark folder & I was able to get it to start booting into internet recovery (No OS). I left the room while it was booting, but when I came back (Less than 5 minutes later), it was dead. Now, the seller did tell me he was able to get it powered on once as well but died on him too. I was powering it off of my DC Power supply, and it was drawing 0.09A while dead.

I figured out that PM_SLP_S4_L was missing (0V), so I started troubleshooting. Now, when I got the board, it was VERY obvious someone else had been working on it. A good portion of the board was covered in flux along with some missing screws. I found out that C1910 has become a wire, so I replaced it with one from a donor board (820-3437). After that, I ended up replacing U5620, U1950 & U1900 because they looked pretty rough. That seemed to have brought PM_SLP_S4_L back. Now when I plug the board in, It draws between 0.20 - 0.40A. I've seen it at 0.40A most of the time, but occasionally lower. When I went to plug it in right before typing this, it went to 0.20A. Keep in mind while it's drawing that the fan is going at full speed.

So, the question now is how bad did I mess up my board lol. Does anybody know what else I should try? Is it bad to take chips off a board with a different board number? As far as I know, 00165 & 3437 are very similar, so I don't think it should be an issue, but as I've said, I don't know much about this. Does anybody know what I should check/try next? Any and all help is appreciated! If I'm doing something wrong, please tell me! Thanks everybody!

 

[2informaticos]

First of all, welcome to the forum!

The chips are pretty much the same; excepting SMC, which has firmware (board dependant).

Test the board alone on the desk.
Nothing connected than power cable from LIO board; keep LIO flex disconnected.
No worry, fan spin fast as normal in such case; also no Magsafe light.
Use an USB mouse connected on the MLB USB port; see if gets steady light.

Do you get VCORE at least?

 

[EthanL1234]

Hey 2informaticos, thanks for your reply! So, assuming ppVCC_s0_cpu is CPU Vcore (I think it is), it is present. I have a steady 1.8 volts on that rail. As for the USB mouse, that wouldn't light up at all. However, with a USB stick, I get a very quick flash of the light. It lasts maybe a half a second?

 

[EthanL1234]

Okay, this is odd lol. So I went to go try it again, and it booted. Only once and it is now back to the previous issues, but it indeed it did power on. This time it didn't have the CPU cooler installed, so I didn't leave it turned on for long but by the time I got the Heatpipe reinstalled it's dead again. I took a few very quick photos. Ignore the mess lol

 

[2informaticos]

Any reason to quote an entire post visible few centimeters above?
Please, maintain forum aesthetic.

Keep the heatsink installed and test the board alone; AS ABOVE EXPLAINED.
Do not put it in the case untill you get it working properly.

Be sure J6100 is clean; can be removed.
Check all SPI Bus Series Termination resistors (more than 20) and their traces.

A bootable USB stick flashing continously confirms 100% USB activity; but not just one flash.

 

[EthanL1234]

Okay sounds good! J6100 looked terrible so I removed it. Would you be able to point out where those resistors are on the board or how to find them? I wasn't lying when I said I was generally clueless lol. Also, not sure if this makes a difference but I thought I'd let you know. When the mac is drawing 0.40A, it has Vcore. When it's drawing 0.20A it does NOT.

 

[2informaticos]

A search for "SPI Bus Series Termination" in pdf, will point you at page 46.
Be sure all their traces are good too.

 

[EthanL1234]

All resistors measure fine and their traces look fine as well.

Now here's something else I've noticed. On MacBook air's, they usually turn on, off, on, off, then it boots up normally. Mine doesn't do that. Should I look into that?

Also, thank you for taking the time to help me!

 

[2informaticos]

Mentioned behaviour is only valid for 820-3435/3437 (2014).

There are few SPI resistors placed on the other board side.
As J6100 was corroded, be sure corresponding traces are good.

Forget PSU and use original Magsafe 2 charger into repair process.
Disconnect LIO flex and check for USB activity on MLB port.

Should be good to reball SMC also...

 

[EthanL1234]

I found one bad resistor on the other side of the board. I replaced it, and the issue persists. No activity on USB with or without LIO flex.

As for the SMC reball, there's no chance of me being able to pull that off yet. I'm going to practice on some working A1181 boards before I try on this.

Anything else I should try?

 

[2informaticos]

Not much to say, untill you reball the SMC...

 

[EthanL1234]

Okay, I will get back to you once I've figured that out. Thanks!

 

[EthanL1234]

Ok, SMC reball completed. I managed to borrow a stencil from a local shop. Seems to have gone pretty well. Unfortunately, same two issues. Either no Vcore or 0.35A draw & no power.

I decided to measure the enable pin on U7200 when vcore isn't present, and it's measuring 8.2V. The schematic indicates that it's supposed to be 12V. Where should I look for that?

 

[2informaticos]

Are you really sure all the traces for mentioned SPI resistors are good?
Check continuity between all resistors, not only resistors value.
As you had corrosion on that area, is the first thing I suspect.
It is also close to SMC, that's the reason to reballed it.

 

[EthanL1234]

Yeah, all resistors ok. Now that was the area that someone f*cked with before I got it, and is covered in flux. Perhaps they gave up after messing around that area for a bit. I don't see anything obviously wrong there aside from all the flux but once again I've fixed one MacBook Logic board to date so what may be obvious to you may look fine to me.

 

[2informaticos]

Pufff, if board was messed up before by someone else, is not easy fix now.
You can have knocked off components, or broken trace god knows where.

Do you really have 8.2V on pin 1/U7200???

 

[EthanL1234]

Yes, when vcore isn't present (about 3/5 times) I have 8.2V on pin 1. When Vcore is present it's the normal 12V.

 

[2informaticos]

I have my doubts about 12V (even 8,2V) on CPU_VR_EN.
This signal comes from PCH area!
If real, then U7200 is f***d and probably CPU too...

 

[EthanL1234]

Oh no no no pin 17 lol not pin 1 (ppvin s0 cpuvr Vin). My bad.

 

[2informaticos]

"when vcore isn't present (about 3/5 times) I have 8.2V on pin 1. When Vcore is present it's the normal 12V."
12V is not normal at all.
Correct voltage for PPBUS_G3H is aprox 8.5V on this board (without battery connected).

Please re-check your measurments, we need accurate information...