Y Cable Hard Drive

[Edilma Howard]

TheSATA interface cable consists of four conductors in two differential pairs, plus three ground connections. The cable size may be 30 to 26 AWG with a maximum length of one meter (39.37 inches). See Table 7 for connector pin definitions. Either end of the SATA signal cable can be attached to the drive or host. For direct backplane connection, the drive connectors are inserted directly into the host receptacle. The drive and the host receptacle incorporate features that enable the direct connection to be hot pluggable and blind mateable.

For 3.5 Inch Desktop Hard Drives the power cable and the SATA cable are separate cables. Every recent power supply should come with a few SATA power plugs. If you don't have enough free plugs, or if your power supply is really old, there are adapters. For data you just need a normal SATA cable.

You've noted that the HD is SATA, so you will need a SATA cable between the motherboard and the drive, and a SATA power cable from the power supply to the drive. -G43/Specification shows that the motherboard has two SATA ports. Perhaps you have one motherboard SATA port used up by an optical drive - you can temporarily use it for this project.

The connector on SATA drives is designed so it can be used with either a combined power and data connector or with two seperate connectors for power and data. In desktop systems power and data are normally wired up seperately.

Power cables are normally part of the power supply. Big brand OEMs will often use power supplies with exactly the right selection of cable lengths and connectors to match the drive bays in their machines. Generic power supplies may have a less-perfect selection of connectors.

Some fancy power supplies come with cables that can be detatched to make the inside of your case look neater, these are known as "modular cables". Be aware that if your power supply uses these that there is no standard for the power supply end of these cables and they can differ between supplies (even supplies from the same brand), so don't just grab a modular cable from some random power supply and plug it into a spare connector on the power supply.

If you need extra power connections or the cables won't reach you can buy power splitter an extender cables. You can also get adapters to go from the older "molex" power connectors to SATA power connectors.

I've been fixing Macs professionally (not through Apple) for well over a decade now. By far the most common thing I do is replace failing hard drives. While Apple's own tools (hardware test, Disk Utility) do almost nothing to positively confirm a failing hard drive, there are several other tools (SoftRaid, SMART Utility) that can read the SMART data and tell you for sure that a drive is failing. So unlike the Genius bar, I can quickly diagnose a bad hard drive without having to infer the problem through symptoms.

But one problem that I've noticed really being on the rise lately, is a failing hard drive cable in MacBook Pros. That's the little flat ribbon cable that connects the hard drive to the logic board. It also connects the sleep light. This is a much harder problem to diagnose, because it generally acts just like a system with a failing hard drive, but the drive will pass a real SMART test with flying colors. You might think "come on, how often does a simple cable really go bad?" Well, I've never had a traditional desktop style SATA cable go bad. But I've replaced a lot of these drive cables and I'm doing another one tomorrow. I never really know if it's going to fix the problem or not though...

... because, there's no way to directly confirm the cable is the problem. I know all about Apple service procedure. I know the official way to diagnose a problem is to start replacing parts until the computer is fixed, and that last part was your problem. But that's not how things go in the out-of-warranty world of independent Mac repair.

So I got to thinking. Computers with bad cables don't crash, or freeze. They just hang for a while randomly, then come back. JUST like a hard drive with lots of bad blocks. So what could be causing this? The only thing I can think of is SATA bus errors that only happen intermittently (on a scale relative to the amount of i/o calls a hard drive does). If that is the case, then there must be SOME kind of utility somewhere that can see these errors? There are plenty of utilities out that that have fancy 3D interfaces, but do absolutely nothing (tech tool etc). But there are a few tools that the Pros use that actually DO stuff. DiskWarrior and SMART Utility are the main tools. If I could find something that can somehow easily and definitively sniff out these bad SATA cables, that would make my life a whole lot easier.

I just inherited a mid-2012 13" A1278 which previous owner said she hardly used in recent years because it got so slow. After resetting the system, wiping the drive and upping the memory from the original base 4gb to 12gb, I noticed a definite improvement. But still really slow and sort of hanging up when installing new OS and other large apps. Even now on MS Office 2016 and Final Draft I get a lot of beachballing. I'm thinking I should try swapping out the Hard Drive Cable and maybe put in a spare SSD I've got lying around while I'm there.

So the cable iFixit sells says it can replace both. But it's pretty costly at $44 (with bracket). I can find some others (with bracket) on Amazon for half of that. But those specifically say they are EITHER for the 821-1480-A cables OR the 821-2049-A cable. Not both. Should I just go with the newer version 821-2049-A?

You also mentioned that Apple modified the HDD mount so it would prevent the case from pressing on the HDD cable. Even tho you said it didn't eradicate the issue, is that something that I can easily accomplish by replacing both brackets?

Brue computing posted an interesting Video on Youtube. The proposition was that the SATA cable problems in certain MacBooks was caused by abrasion against the machined inside of the aluminum case. Their solution? RED TAPE!

Do you ever notice any physical wear on the cable? One youtube "fix" I saw involved simply insulating the cable with a piece of tape from the MBP's case where it had actually scraped a tiny portion of the very thin insulation off.

I had kept the three old cables so I decided to find out what had gone wrong with them. There are 5 thin copper tacks, which connect to the 7 pin side of the SATA connector. I used a multimeter to do a continuity test on these tracks. I found that on all three cables one of these tracks had broken at the same place. The cable does a tight right angle bend at the point it passes over the optic drive. The cable flexes at this point and eventually one of the copper tracks breaks. I found that if I flexed the cable at this point the track would make and break contact.

On later versions of the MacBook Pro Apple modified the HDD mount so it would prevent the case from pressing on the HDD cable. They also introduced an upgraded cable 821-2049-A, which replaced the original 821-1480-A. Unfortunately, upgraded cable still eventually breaks. This time I have taped the cable to the optic drive to try and prevent it flexing. Time will tell if this helps. The cables are quite easy to replace and I keep a few in stock.

One way of partially checking the problem is to externally connect the HDD (e.g. use a dock or SATA to USB cable) and see if the MacBook boots correctly. You need to hold the alt key down when starting the MacBook to be able to select the external drive.

My MBP Mid 2012 shows a question mark in a gray folder (on white screen) when fired-up.

Thought it could be a HD failure. Invested in a brand new Samsung EVO 850 SSD and same problem occurred until I learned about the famous "Flat wire A1278" issue.

After replacement of the flat wire (with felt protection to prevent further damage) and entire recovery, everything was great, super fast booting, app opening in a blink of an eye, me happy.

End of 2017:

Same question mark in folder appears again when firing-up the machine.

Assuming the SSD was faulty, I swapped it against the original HD and Boom, the machine works fine again, well much slower but still.

Since it has a 5 year guaranty, I brought the SSD to a Samsung Service Center (Bangkok, Thailand) and 10 days after, they declared the SSD is actually fine and might just have needed a firmware update. Ok why not after all...

They printed out many screenshots of the Samsung diagnostic software showing that all was in the green and one last shot showing the SSD up and running in a Mac environment connected via USB port (attached pictures)...

"USB port connected" and "internally on a MPB connected" is something quite different... anyways...

Today,

I put the Samsung SSD back in and even if it appeared in the list of drives under Recovery mode, the SSD cannot be either verified, repaired, erased/formatted as it always ended up with the same error message (see attached picture).

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