User profile for user: Sebastian Kuhn
Sebastian Kuhn Author
User level: Level 1
72 points

Brand new MagSafe adapter with older MacBook Pro

I recently bought a new MagSafe 85W power supply so I don't have to always move the one that came with my (early 2008) MacBook Pro 15" back and forth from home to work. The one that came originally with the MacBook Pro has the rectangular plastic plug at its end - see http://support.apple.com/kb/HT2346#661-5036 . Apparently that one isn't manufactured anymore, so instead they sent me a new 661-5474 with the sleek "L-shaped" metal plug. Surprise: This one works SOMETIME, but after a while it stops working (neither the power supply LED lights up nor the MacBook Pro recognizes it's plugged in). When that happens, NONE of the usual tricks (unplugging and re-plugging into AC etc., see http://support.apple.com/kb/ts1713 ) work; the only thing that DOES work is doing a complete reset of the power management unit inside my Mac - unplug everything, remove the battery, then press the power-on button for at least 5 seconds. Note that the OLD power supply never had this problem and continues to work for me even if the MacBook is in this funky state where it doesn't recognize the new one. Apparently this can even happen to the newer MacBooks (unibody) for which the new power supply was originally designed - see the post at http://discussions.apple.com/thread.jspa?threadID=2484601&tstart=15 . Perhaps my older MacBook is overly sensitive to how (in which sequence) I unplug it - see the post at http://discussions.apple.com/thread.jspa?threadID=2499645&tstart=30 . Or the new adapter has slightly different voltages/currents that are just slightly out of tolerance for the older MacBook. There definitely is no problem with mechanical contact (dirt, stuck pins etc.) - even when the new MagSafe adapter doesn't work with my MacBook anymore, it still works with other (newer) MacBooks. Vice versa, resetting the PMU does the trick (so far, knock on wood) but is hardly a satisfying solution (if you have to do it several times a week, as in my case).
Just wanted to give a heads up to others and see whether anyone else has similar experience (and/or maybe even a SOLUTION???).

MacBook Pro early 2008, Mac OS X (10.6.4), 2.4 GHz 2GB 170 GB HD

Posted on Jul 16, 2010 7:06 AM

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47 replies
User profile for user: Sebastian Kuhn
Sebastian Kuhn Author
User level: Level 1
72 points

Jul 16, 2010 1:05 PM in response to carl wolf

Thanks for some of the advice. I am sure that the NEW MagSafe adapter is not defective, as it reliably works with newer MacBook Pros. In fact, when I first got the new adapter, I THOUGHT it was defective and Apple agreed, sending me a second one. However, BOTH of them showed the exact same behavior (sometimes working, sometimes not with my older MBP), so it clearly is a compatibility issue.
BTW, I found that this problem has clearly happened to other people - if you go to the Apple Store for the new MagSafe power adapter -
http://store.apple.com/us/product/MC556LL/A?mco=MTY3ODQ5OTY
you can read some comments (e.g. "Yes for Unibody, NO for older MBP's") referring to the same problem.
Given that this new power supply (with the L-shaped plug) appears to be the ONLY one Apple still makes, I hope they can figure out how to fix this problem, or else they will have a lot more unhappy "older" MBP owners in the future...
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User profile for user: eww
eww
User level: Level 9
53,122 points

Jul 16, 2010 2:00 PM in response to Sebastian Kuhn

This seems to have been a real oversight on Apple's part. It would have been easy to make the part of the new plug that contains the contacts just a millimeter or two longer, and that would have made it compatible with all MBPs and MBs including the oldest ones.

The new adapters have another drawback, too: in the interest of getting the power cord away from the side of the computer (where there are apt to be other cords plugged in anyway, so how much does it matter?), Apple has partly sacrificed the quick, safe disconnection of the MagSafe plug when it is tripped over or jerked. If a jerk happens to come from the rear, the whole computer will get jerked along with the cord before the plug disengages. This never happened with the original, straight MagSafe plug, and that was a huge advance over the mechanical connectors it replaced. You absolutely couldn't pull a MacBook or MacBook Pro off your desk and onto a hard floor by tripping over its cord. Now you can, if you're unlucky or careless enough to trip over it in back of the computer. Fine if your desk is up against the wall, but if you're at a table in the middle of a room, not so good. It's a step backward.

Message was edited by: eww
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User profile for user: 004forever
004forever
User level: Level 1
0 points

Jul 22, 2010 1:37 PM in response to Sebastian Kuhn

I'm having the exact same problem. As a side note, it's not reseting the SMC that fixes it, it's just taking out the battery. This really is a huge problem. This was the only kind that I saw at my local(a brief 2 hour drive away) Apple Store and they only work properly with the Unibody Macs? You mean the people with older computers and the ones who are more likely to need a new cord are SOL? That's pretty ridiculous.
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User profile for user: Sebastian Kuhn
Sebastian Kuhn Author
User level: Level 1
72 points

Jul 23, 2010 2:51 PM in response to 004forever

Thanks for your confirmation, and the very useful observation (which I indeed can confirm) that it suffices to take the battery out and put it right back in whenever my "older" MacBook Pro doesn't recognize the new power adapter.
I don't know what this means, but maybe some Apple engineer who might see this post has an idea how this problem could be addressed through a firmware update (there's always hope! 😉. In that spirit, I add another observation: It turns out that I CAN switch back and forth between the old and the new power adapter as long as 1) I do NOT shut down the MacBook in between, but rather put it to sleep (using the pull-down menu underneath the Apple symbol) and 2) not enough time elapses for the battery charge state to change significantly. In other words, the Mac "forgets" about how to get along with the new power adapter ONLY if either I shut it down (with either the old one or the new one connected) and then try to (re)connect the new one (after a period of no adapter being connected), or if I disconnect the new one and the battery discharges a little. Strange!
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User profile for user: carl wolf
carl wolf
User level: Level 6
14,631 points

Aug 6, 2010 1:05 AM in response to Sebastian Kuhn

"Thanks for some of the advice. I am sure that the NEW MagSafe adapter is not defective..."

I'm confused: you posted that the new power adapter does not work with your computer, other people confirm that the new power adapter doesn't work with the older computer, and you still claim that nothing is wrong with the power adapter. The only other thing is that your computer is defective, and you should bring it to Apple for analysis. When the Genius says is works OK, and you say that it doesn't work with YOUR adapter, you will be told to bring the computer back with the power adapter that doesn't work.

I'm trying to help you out, but if you ignore my advice, you're not going to get your problem solved. Chasing a tail is fun for a puppy and, if that's what you prefer to do, have at it. I'm just saying.
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User profile for user: Sebastian Kuhn
Sebastian Kuhn Author
User level: Level 1
72 points

Aug 6, 2010 4:42 AM in response to carl wolf

I'm sorry you're confused - I tried to explain that the new MagSafe adapter I received is not a defective (individual) unit - but that doesn't mean that "there is nothing wrong with it" - it is just designed badly. I thought the difference between "defective" (= broken, kaputt, malfunctioning, ...something that can be fixed by replacing it with an identical model) and "not working with older Macs" (NONE of the new powers supplies works with mine and - as this forum shows - any number of other people's) was clear. Maybe it would have helped your understanding to read the posts carefully, but maybe that's also only for puppies (and not for important people busy trying to break the record of most posts).
Anyway, you are correct that I could also waste a perfectly good afternoon going to my nearest Genius bar; however, since neither my Macbook Pro (which continues to work reliably with the old power supply) nor the new adapter are intrinsically broken, I'm not sure what that would accomplish (maybe a report to Apple about this problem? But I did report it over the phone to a tech rep!)
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User profile for user: carl wolf
carl wolf
User level: Level 6
14,631 points

Aug 7, 2010 5:36 AM in response to Sebastian Kuhn

There are several reasons that the newest power adapter will not work with an older computer. Could there be an inherent design defect? Yes. Could there be an internal component tolerance stack-up? Yes. Could a single component not meet spec? Yes. Could a wrong value component be the culprit? Yes. If you do not bring in the power adapter that is demonstrating the problem (even though you believe that the power adapter is not defective), the Genius could say, "Your computer is fine. Let's have a look at the power adapter." Or, "Apple has ascertained that a small number of units with a specific date code could cause a problem. What is the serial number of the power adapter?" So, when you bring in your computer, bring the power adapter too.

On another note, do not troubleshoot the problem for the Genius - it's up to the Genius to discover what the problem is. Simply report the symptom: "using the new power adapter, my computer only charges intermittently" - or something like that.

The power adapter has over-temperature, over-voltage, and over-current protection circuitry, and it reads as though the power adapter is too sensitive.
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User profile for user: znowboarding
znowboarding
User level: Level 1
7 points

Aug 7, 2010 6:40 PM in response to Sebastian Kuhn

I too have had this problem recently, My original 85w magsafe has not been working properly so I decided to try and use my girlfriends from her brand new 15" unibody just to see if it would work, It does, but only occasionally and in a seemingly random fashion. Sounds more like a hardware issue than a coincidence apple.

I need to go find a replacement for my old "T" style 85watt and I would like to buy a non 3rd party part to get the most out of my MBP, If I'm going to have to remove the battery each time to reset the power options this is going to be a serious drawback to owning my computer.

According to apple on their magisafe troubleshooting support page

http://support.apple.com/kb/ts1713
"If you receive a replacement MagSafe adapter with a "L" style MagSafe connector when you previously had a "T" Style MagSafe connector, the "L" style adapter is fully compatible with your Apple computer."

So, what next...
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Brand new MagSafe adapter with older MacBook Pro

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