Released October 2008 / 2.4, 2.53, 2.66, 2.8 or 2.93 GHz Core 2 Duo Processor

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Function of MBP logic board copper pins

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Hello

What function do the red circled copper pins do have, which are "all over" the logic board of e.g. my MBP A1286 or A1297?

One of them has been broken and it seems as there is a copper line below it on or within the PCB.

Picture has been attached.

Regards, Stone

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I've always wondered the same thing, hopefully someone will shed some light.

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What I can tell you is they are not described in the Apple Technicians Guide. So they don't offer a general service tech anything useful, that means they are used in manufacturing process or may offer a board level tech something useful at a test/power point. Thats not to say they don't have a function as a VIA (electrical pathway though the PCB board layers). So a damaged one could have an effect here. Are you having issues with your logic board?

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Hi Dan

Yes, it is all about the problem with my 2009 A1297 which sound card is not working properly. To sum up: sometimes it is working (it seems, if the MBP gets warm and some little pressure on the bottom).

I was thinking of them pins as being reference points for measurement or even grounding points. I am not sure if they do touch the bottom cover but it is possible.

If so and they need to touch the bottom then MBP would not run properly without bottom case installed.

To be honest I haven't had the time until now to have a closer look to my "broken" A1297, but I remember, that one of these pins broke off the PCB and it happened during normal use, so the pin felt off the case, as I opened the MBP for HDD change.

I also remember, it is one of the pins which can be found right hand side, if the MBP is placed on its top and the superdrive is on the left hand side.

I could not find them on the schems, too.

Will have a closer look tomorrow, if the sound chip is near the broken pin.

Regards, Stone

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Can you take some hi resolution pics of the area when the pin is now missing and one just back a bit so we can ID that part of the logic board. So we can see the damage and ID what the circuit is.

Update

Well I did some more investigating and was able to locate on the schematic for this system. The pins as it turns out are tied to the chassis ground.

So one has to assume these are fixture guides used in the assembly process or Apple thought they needed an EMI shield to cover over the PCB as they are laid out in a pattern.

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Hi Dan

Did my best, but I am always shaking a bit. You can see that it is right below the USB port in the middle; first of all I was thinking it is a mount point or something else of the USB port, but as this is a 2-layer or maybe 3-layer board it is obviously not.

The pictures can be loaded from here:

http://root.dietmarstein.com/tmp/a1297/p...

http://root.dietmarstein.com/tmp/a1297/p...

http://root.dietmarstein.com/tmp/a1297/p...

Regards, Stone

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Ah ... just found it in the scheme. You are right. Seems as if they are diagnostic measurement (reference) points. Their label is 1.4DIA-SHORT-EMI-MLB-M97-M98 e.g., where I am thinking, 4DIA maybe an abbreviation for "for diagnostic".

They are also connected to ground.

Hard to say, if they 've got a function above that.

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And the location of the sound chip itself, labeled with u6200 ... http://root.dietmarstein.com/tmp/a1297/p...

http://root.dietmarstein.com/tmp/a1297/p...

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Looks like we were on the same path here ;-} I would take a good magnifier and inspect the solder joints of the pathways leading from the speaker leads back to the chip. You could also have a bad connector or the speaker lead is being pinched.

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I'm having a issue with my macbook pro. It's turno off all of a sudden.

After cleaning everything and even replacing the thermal paste, it is still having the same issue.

It was only now I saw those pins and I saw that some of them are broken and maybe not touching the metal case, so not grounding as well.

I wonder if that could be the cause of the issue I'm having and if so, how to fix it.

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They are not active (no direct connection to the chassis here), they are used either in the manufacturing process for the automated parts install machine to index the board to or Apple thought they might have needed additional EMI protection which later on they didn't need.

But! If you've damaged them you could have damaged the logic board! You see these press fit pins go though the logic board so if you forced it to the side it could have delaminated the board causing the foil traces to break.

So the answer is Yes! If you damaged them, it could explain your problem here. Not much you can do to fix this other than replace the logic board.

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Thanks, Dan!

Just found out is a GPU issue. I'll have to have it replaced.

For no,w I disabled the "automatic graphics switching" option in the Energy Saver menu of the system preferences so I'm running only with the internal graphics processor.

I hasn't fixed the issue but it's giving me a little bit more of working time.

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>> deleted: Deliberate design for MBP failure. << They arc with the AL clamshell back, pitting it after years, and the springs and pins fail from normal stresses of handling the unit. They measure about 2 ohms to ground and judging from the pits on the inside of the AL case after years, conduct some significant, likely static currents from the case directly onto the main logic PCB.

Update (07/26/2016)

The arcing and pitting is very real at clearly-defined round cutouts in the insulation inside the clamshell back cover (see photo links below). There's a remote chance it could be the result of galvanic corrosion from dissimilar Cu/Al metal contact but more likely the pits are from high-voltage ESD across an imperfect contact and what appears, I realize now, to be the intent of these pins in the first place.

Pictures of the pits and the round holes in inside back cover plastic:

https://drive.google.com/file/d/0BxyFY-j...

https://drive.google.com/file/d/0BxyFY-j...

Reconsidered, it makes sense ESD discharges find their way to a ground plane on the Main Logic PCB, rather than to any individual components or to any non-ground circuit path.

Continuity of the copper push pins to the case doesn't appear essential, they appear like little 'lightning rods' for the Main Logic PCB, to the extent spots on the interior of the clamshell get eroded away (presumably) by electrical arcing.

Also one of these pins got loose -somewhere- not a good thing, hopefully somewhere else by now, and another pin's shroud has been 'bent' to the extent the spring-housing is cracked, likely by the normal process of handling the MBP with one hand, which stresses the aluminum clamshell case-back and deforms it against a few of these pins.

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Arc? How so? As I pointed out (see schematic diagram) these pins are ground so there is no current pathway possible (static or power). I don't see any design failure here electrically.

I would agree if you open the system and damaged one or more of the pins by bending it to the side you could delaminate the board breaking one or more of the foil traces and one might claim thats poor design.

But, is that Apples fault here or someone being careless? Sadly it's us being careless!

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Missing pin parts and pins deformed through clamsell case flexion are a design flaw.

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Still don't see this as an arc condition. Remember the aluminum shell is a Faraday Cage So any static will stay on the outside skin of the shell it can't enter.

With that said entry of a lightning strike though the MageSafe connection or other interface (USB, FireWire, Display Port or Ethernet network) could jump from the logic board ground plane through the pins and arc across to the case if the case pathway was a less resistive path for the lightning strike. But that is highly unlikely!

To be honest here I suspect you just banged the bottom causing the pins to hit the cover denting it. The metal tang you see in your photos fit into a plastic receiver on the mid plane chassis to offer a stand-off I often see them broken from bangs.

In this series the bottom cover is not as structurally strong as the newer models as the battery access makes it weaker.

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Remember this was the very first Aluminum cased 15" MacBook Pro! So Apple was still learning what works and what doesn't, which is likely why they dropped the removable battery.

Then again, we have to take some of the responsibility here by not using our systems as a hammer ;-} Comparing like systems at the time, Apple's systems were more rugged than other systems. I can attest to that as I had to fix them!

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Stone will be eternally grateful.
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