Apple’s Proprietary 300-pin Connector Is Not Proprietary At All

[Nullcaller]

Ladies and gentlemen, we got 'em. Kind of, sort of... Let me explain.

In every topic I've come across, in every teardown article and every video, the 300-pin connector Apple used for the CPUs on the G5s and G4s (except for the 'Yikes!' ones, I guess), as well as for connecting all the different boards in the 2013 Mac Pro (affectionately known as the 'trash can'), is simply called 'proprietary 300-pin connector', thus waving away any questions for what it actually is, how it's called, and whether or not you can order one: Apple designed it, Apple owns it, and Apple will never sell it to you.

The 300-pin connector on the Power Mac G4 Quicksilver (courtesy of iFixit and Chris Green, under CC BY-NC-SA 3.0)

The Late 2005 Power Mac G5 processor daughter card, featuring the 300-pin connector (my own photos, CC-BY 4.0 unless forum rules state otherwise)

The 2013 Mac Pro halfway through the disassembly process and the bottom connection board, featuring three 300-pin connectors (courtesy of iFixit and Andrew Optimus Goldheart, under CC BY-NC-SA 3.0)

This is, in fact, not true. The pinout is probably different on virtually every device model, that's for certain. But the connector itself is an off-the-shelf one, and its name is 'Amphenol MEG-Array Connector'.

I've had a hunch it was not a proprietary Apple-designed connector for a while. After all, Sonnet somehow had access to it. I doubted that it was Apple-sanctioned, and I also doubted they went to the trouble of copying it for a couple of CPU boards. I've been trying to find what it was for a while, but unfortunately, it's extremely difficult to find any connector or any SMT component if you don't know what exactly you are looking for. The right keywords for the type of connectors I was looking, in the end, were 'SMT high density connectors', which led me to 'SMT high density array connectors', and searching for 'array connector' on AliExpress, I found the '84740-102LF' connector, which looked suspiciously like Apple's 300-pin connector, except it had 400 pins.

P.S. This post is brought to you by my ongoing investigation into whether or not it is feasible to convert a Late 2005 Power Mac G5 DC board into a Quad board by soldering on an additional socket. Please, do chime in if you have something interesting to tell on that subject!

 

[Nullcaller]

The MEG-Array connectors come in different variations based on pin count and mated heights.

The mated height on the Late 2005 Power Mac G5 seems to be 8 mm. I've measure the top of the daughter card to board distance to be 9.87 mm, and the daughter card thickness to be 1.83 mm, so the mated height seems to be 8.04 mm, give or take 0.2 mm. The only height that fits out of the available ones (4, 5.5, 6, 8, 10, 11.5, 12 and 14) is thus 8 mm. So the part numbers seem to be 84500 for the plug (CPU side) and 84553 for the receptacle (logic board side) as per the datasheet, and DigiKey seemingly lists the connectors as 84500-102LF and 84553-101LF. (after the dash, the first number seems to refer to rated mating cycle amount, 0 for 50, 1 for 100, 2 for 200, the second to the plating type (9 or 0), the third one idk what it refers to, and the LF stands for lead-free)

For the older G5s (AGP/PCI), mated height seems to be 5.5 mm. I measured it to be 5.12 mm directly (since I have a desoldered socket lying around), rounding to the nearest available height seems to yield 5.5 mm. The part numbers are 84500 for the plug (CPU side, unchanged) and 84502 for the receptacle (logic board side) as per the datasheet. DigiKey lists the 84502 socket as 84502-101LF.

The motherboard sockets seem to be out of stock at most places, but it seems like there's a few resellers which might have it, if you look around. The CPU side plugs seem to be in stock both at DigiKey and Mouser.

 

[Matias_]

Interesting finds! A while back I was researching those frustratingly unobtainium Airport Runway cards for the late 2005 PMG5 card, trying to evaluate if it would be easy to design a replacement (I think it might be).

I was in a similar position in regards to trying to identify a weird SMD connector. I asked some EE friends and I think we ended up on "Molex SlimStack Board-to-Board Receptacle" but I don't have any real boards to measure, nor could I find high resolution pictures and I also don't have any PCB designing experience so I shelved that project for the time being.

If you are still interested I can provide pictures of the 2.5GHz G5 daughtercards from the Quad, I have 3 sets of them that are dismantled from the LCS but still have the VRM heatsink attached (I'd rather not remove them if I don't have to). I can't provide measurements right now because my set of calipers broke and I don't know where I left my spare but I think they are identical in size and almost identical in components, they just have some additional VRM components that are left out on the 2.0GHz and 2.3GHz daughtercards.

 

[Nullcaller]

Thanks!

I was in a similar position in regards to trying to identify a weird SMD connector. I asked some EE friends and I think we ended up on "Molex SlimStack Board-to-Board Receptacle" but I don't have any real boards to measure, nor could I find high resolution pictures and I also don't have any PCB designing experience so I shelved that project for the time being.

Yeah, from my little googling session just right now, I think finding the exact connector match is probably going to be more difficult than finding a needle in a haystack. With the needle, at least you can theoretically get filthy rich and buy an MRI machine, so that it comes out flying.

I've also looked at the Molex stuff, and I honestly don't think that's it. The runway card connector has some weird funky stuff on the edges of the connector, but there's nothing like that on the Molex connectors. I think it'll probably work, though, if you find a close enough match in terms of size and pitch. I know this connector type as the 'FPC connector'. Virtually every connector inside a modern phone looks like that now, and they usually go on little flexible printed circuit boards (hence the name) that connect various components inside phones.

Remaking the runway board is a fun project idea, though. You can't think of a better starting point EE project. Datasheets for the older PMG5 model seem to suggest that the gold fingers connector on the side of the runway card is just PCI in a weird form factor (though don't go plugging in any mini PCI cards you have lying around into that connector, 'cause it will go up in flames). And it seems like the cards from older PMG5 models are compatible with the newer models, so I would assume it's still PCI even on the Late 2005 PMG5s, with their fancy new PCIe connectors. It seems like all the runway card really is, is just a few decoupling caps on what is probably a 2-layer board. Maybe 4-layer, if someone at Apple was feeling fancy that day, and wanted to have a ground plane between the signal layers or something. So all you have to do, is figure out what values those caps are, and how not to screw up the signal integrity. And also, the connector part number, yes.

If you are still interested I can provide pictures of the 2.5GHz G5 daughtercards from the Quad, I have 3 sets of them that are dismantled from the LCS but still have the VRM heatsink attached (I'd rather not remove them if I don't have to). I can't provide measurements right now because my set of calipers broke and I don't know where I left my spare but I think they are identical in size and almost identical in components, they just have some additional VRM components that are left out on the 2.0GHz and 2.3GHz daughtercards.

If you have some spare time to take the photos (or measurements), then send them my way! Thanks!

What I want to know is kind of the positions of heatpipes and how they're attached to the VRM heatsinks. Also the diameter of the heatpipes, because I can't really tell from the pictures. I know the heatsinks are pretty much the same between the Quad and the 2.0 GHz cards, but (1) I will obviously be trying to make my own little Quad-like heatsink and (2) maybe someone will want a model of the Quad VRM heatsink eventually, you never know. I just think it's better to make the thing as close to the real deal as possible, then it might be useful to people as a reference thing, and not just to me as a do-it-once-then-forget kind of thing.

And as for removing the VRM heatsinks, I honestly don't think the VRM heatsinks should be detached from the daughtercards, like, at all, ever. I detahced mine from the spare 2.0 GHz CPU I had, and the gluey thermal adheisive pad thingamajig isn't holding on to the heatsink as strong as it did before. Which can probably be either mildly bad or pretty fine. On the Quad processor cards I think this has a chance of being more than mildly bad, so don't do it.

You could probably replace the pad things with thermal paste, and it'll probably be better in terms of cooling, but idk whether it'll be as good in terms of longevity.

 

[Nullcaller]

So about that runway card FPC connector. I've tried looking through DigiKey's catalogue of 40-pin FPC connectors (it's actually smaller than you'd imagine), but that yielded nothing. I did suspect Panasonic for a small while, but ultimately couldn't find a perfect match for the runway card connector.

But when that failed, I had an idea for another angle. The runway card isn't the only thing Apple ever used the A1126 combo WiFi/BT card with. (Naturally, I've memorized the model number by now) So if you could find schematics of other Apple products using the A1126 card, they'd probably have a convenient little label above the connector, telling you exactly what it is. Well, spoiler alert, they do. But the story is way more intersting than that.

Here's the schematic I found first. It says it's for an iMac G5, which I was searching for, but what it actually is for Late 2005 15.2" PowerBook G4. You can tell, because it says "PB15" on the first page, and has everything connect to the "Apollo CPU (MPC7447)", which just smells like a G4 chip. It also can't be a 2004 or Early 2005 machine, because those ones don't have the connector for the A1126 card, and, as we will now find out, this one does. Here it is:

With a convenient label above, as promised. If we search up QT510806-L111, we stumble upon something called Foxconn Interconnect QT51 series (datasheet attached), and would you look at that!

You may notice, however, that the connector doesn't exactly look like the one on the runway card. Let's see what iFixit has to say about that. The Airport card replacement guide doesn't seem to show what the board connector looks like. It does show that the board is connected to some sort of extender, however:

(courtesy of iFixit)

I've also looked through the logic board removal guide, which doesn't seem to contain photos of the extender, but it does contain this photo here, which shows the connector to which the extender cable connects:

(courtesy of iFixit)

Looks pretty similar to the datasheet, huh?

But wait, what about that iMac G5 I was looking for? Maybe we can find the schematic for the iMac G5, and then we'll know for sure. If it has the same connector part number, it must be the right one!

Wait, what's this here? A schematic for the iMac G5? Let's see then!

Ah. Well then, the extension must have had a different connector, and the PowerBook G4 datasheet lists the board connector instead. Let's see what the datasheet (attached below) says about the aptly named 20-5602-080-041-829.

Well... That doesn't look like it at all. IFIXIIIT!

(courtesy of iFixit)

Buh waih... That's an iMac G5. And it has... a different connector... So... The runway card, the iMac G5 and probably the PowerBook G4 all have different connectors for the A1126 Airport combo card. It seems like the iMac G5 uses the 20-5602-080-041-829 connector, and the PowerBook G4 the QT510806-L111 connector, and to know what the runway card uses, you'd pretty much have to have a schematic for it.

So, in short, it doesn't matter what connector you use, as long as critical dimensions are the same and they work together. Mind you, that's not me talking, that's Apple. In any case, you now have two datasheets to work with, and, most importantly, the critical dimensions for the connectors. Thus, as this forum's resident self-proclaimed interim chief connector detective, I consider this mystery solved.

(20-5602-080-041-829: "And I would have gotten away with it too, if it weren't for you meddling kids!")