replacing Apple magsafe 85W charger with a normal laptop PSU possible? - Page 1
Forum section: electronics / repair

author: Electr0nicus
author_rank: Regular Contributor
timestamp: July 19, 2014, 03:56:59 am
content: Hi!My sister has a macbook pro 17" with a magsafe 85W charger. She had the standard problem with the broken cable a half year ago, which I fixed for her with some soldering and a few layers of heatshrink- tubing.The charger worked since then, without any problems, until yesterday. So she again asked me for help. So I inspected the cable, which was fine. No additional breaks were visible. Then I measured the voltage on the magsafe jack, and wondered that it was only 0,45V. Right at this point, I was pretty sure that the charger is at fault, because with a broken cable the voltage would've been 0V.So I opened the charger carefully, which took forever. It seems that Apple has a contract with 3M, because there was so much glue and tape in that charger, i haven't seen something like this beforeAfter finally getting down to the PCB, I inspected it thoroughly but found no obviously charred components. I located the fuses (input and output) and both were fine. Then I desoldered most of the main switching semiconductors, and tested them - all were fine. I also checked the main filter cap, and the output caps - all were fine. So the charger is pretty much unrepairable, because the main driver IC is maybe a proprietary chip, with no datasheet available on the internet. The SMDs are also stuck down with some sort of red glue (maybe epoxy) which makes it impossible to desolder even the smallest SMD component.So I thought, if it wouldn't be possible,, to connect a normal 19V 4.5A laptop PSU (which I have a few lying around for no particular purpose) with the existing charging cable, to run the mac with that. The cable from the carger is also only 2way, so the magic happens in the magsafe connector, where a 1wire eeprom is located. The problem is, that the charger gives out 2 voltages, 16.5V and 18.5V, presumably load dependent (because there is no feedback path between mac and charger). So the question is, would it be possible to run it from 19V the whole time? Because I would rather use a standard laptop PSU, instead of buying a genuine apple charger (which everyone knows is the greatest design fail in apples history, it's so flawedhttp://store.apple.com/us/reviews/MC461LL/A/apple-60w-magsafe-power-adapter-for-macbook-and-13-inch-macbook-pro). This charger was only 2.5 years old and moderately used, and failed not long after the warranty was over. I'm on the other hand, working on an old FSC laptop with over 35000 working hours, and still with the original PSU.Kind regardsGregor

author: XOIIO
author_rank: Super Contributor
timestamp: July 19, 2014, 05:12:55 am
content: Of course it's possible, but is it worth it?I believe that the MacBook needs to "talk" with the cable to accept a charge, so you would need to reverse engineer whatever communication is going on. You could also just swap the cables, however you would need to add some stuff into the laptop charger to get it to work properly, no clue why the apple one puts out two votlages, but you would need to have a 16v regulator then.Honestly for all the hassle I would just get a new charger (though I would not have gotten a mac in the first place)

author: josem
author_rank: Regular Contributor
timestamp: July 19, 2014, 06:19:00 am
content: The charger (not the magsafe connector) does detect a Mac by sensing a precise resistive load and only applies power after that. This is a safety function, if you skip this test you could potentially be delivering power to the exposed charging pogo pins which could be short by random paper clips etc.This page explains the sequence of events:http://www.righto.com/2013/06/teardown-and-exploration-of-magsafe.htmlI'd suggest getting a new power supply, destroying the MBP motherboard or creating an unsafe situation could prove to be a lot more expensive.

author: XOIIO
author_rank: Super Contributor
timestamp: July 19, 2014, 06:53:10 am
content: Quote from: josem on July 19, 2014, 06:19:00 amyeah that too, I can't imagine the cost of a MacBook motherboard compared to a PC one.

author: Electr0nicus
author_rank: Regular Contributor
timestamp: July 19, 2014, 07:50:38 am
content: Yeah you're right. I'll advise her to buy a new charger.I hoped there would be a easy fix to that problem. What I've learned from that is, that I never bought a apple device before and never will do so in the future. I like to be able to fix stuff when needed, and not beeing restricted by a company with their proprietary stuff. It's shocking that apple doesn't let you fix someting simple and low-level as a power adapter, by impementing some weird (and useless) protocol.Thanks anyways.Gregor

author: amyk
author_rank: Super Contributor
timestamp: July 19, 2014, 12:55:09 pm
content: Which model is it exactly? You can get schematics for most of them (thank the Chinese)... and all the ones I've seen have basically the same power system circuitry as any other PC laptop with 16-20V input. That means anything from ~14V up to 20V (24V if you're feeling brave) will be fine - the lowest rated components on the main DCIN bus are 25V caps. Apple's dual-voltage scheme is probably for passing some sort of efficiency testing but not necessary at all. I personally wouldn't worry about giving it 20V, the buck converters will draw less current and there'll be less heating too.The ID pin EEPROM is only necessary to let the battery charge, it will still power on and run without.Dell has a similar scheme on their laptops. Almost all laptop PSUs have short-circuit protection too.The only thing I'd warn you about isGET THE POLARITY RIGHT!!

author: gxti
author_rank: Frequent Contributor
timestamp: July 19, 2014, 03:35:45 pm
content: The dual voltages are for backwards compatibility, older laptops only supported the lower voltage. I remember reading about some sort of dance where the laptop pulled a certain amount of current from the lower voltage in order to tell the charger that it supported the higher voltage.

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: July 19, 2014, 03:48:52 pm
content: Try an SMC rest and see if it starts charging again ,ive had to do this recently after replacing a magsafe jack in a 13" unibody mac pro .http://support.apple.com/kb/HT3964

author: corrado33
author_rank: Frequent Contributor
timestamp: July 22, 2014, 08:16:12 pm
content: Quote from: Electr0nicus on July 19, 2014, 07:50:38 amOn Topic: Don't risk it, just buy the new apple charger.Off topic:Sure is a lot of apple hate in this thread.I'd LOVE to hear the response you get for ANY computer company asking them if they support you fixing the power adapter for their computers.Hell, I'd LOVE to hear the response for ANY computer company asking them if you can use anything except the original charger supplied with the computer.Apple hating fanboys.Sure, companies should just design their products so that the end user can fix them... GREAT design strategy. Especially when 98% of the end users are as clueless as your sister.I (obviously) like apples, however I do not currently own one. I really enjoy working on it at work, but at home I have a linux box and a windows gaming PC, so no,I am not an apple fanboy. I will buy an Apple when I graduate though because I enjoy the OS more than any windows OS, and hell, I'll take the android argument of "having more freedom". I like my damn useful console, instead of whatever the hell windows gives you.

author: amyk
author_rank: Super Contributor
timestamp: July 23, 2014, 12:04:57 pm
content: Quote from: gxti on July 19, 2014, 03:35:45 pmThat's not the case, the only other range is 9-12V with 16V components in the power circuits and those laptops can't take the 16.5V this adapter puts out at its lowest. I believe it's more of an efficiency hack to pass some sort of testing.I posted a bit about that here where someone found the dual-voltage behaviour:https://www.eevblog.com/forum/projects/apple-magsafe-power-brick/The voltage ranges come from the fully charged voltage of lion batteries, the fact that buck converters are usually used to charge them, and the voltage ratings of the capacitors on the main DC bus. A 2S pack will have a voltage range of ~6-8.4V empty to full, thus needing an AC adapter in the 9-12V range and 16V caps. A 3S pack is ~9-12.6V, and a 4S is ~12-16.8V; they could use different voltage adapters, but since the next highest voltage rating for caps is 25V, in practice they result in the same range and an 18-20V adapter being used. The exact voltage (18, 18.5, 19, 19.5, etc.) doesn't matter, it's whatever the OEM could supply.QuoteUnlike many others (with the exception of Dell), Apple chooses to unnecessarily complicate its adapters with extra failure-prone components, when all it could do if it wanted to e.g. detect the plugged-in adapter wattage was use a simple ID system likea resistor.

author: vvangelovski
author_rank: Newbie
timestamp: July 24, 2014, 07:29:59 am
content: Just get a charger from DX.com. Much more durable than the genuine apple chargers at a third of the price.

author: Electr0nicus
author_rank: Regular Contributor
timestamp: July 27, 2014, 11:40:26 am
content: My sister got the new charger/PSU (genuine Apple one) on Wednesday and everything works again now (but for how long)But before that, I testet the output voltage of the openedoldadapter, while connected to the MBP. It was stange, that the output voltage, directly measured on the output solderpads of the opend PSU, was constant 16.5V without much ripple. Nevertheless the MBP didn't start (battery was depleted at that time). So I assume, that originally not the PSU was at fault, but the magsafe connector with its little 1wire ID Chip inside. WIthout the MBP connected, I could reproduce the 0.45V directly on the PSU PCB, so it's a short- protection feature as josem wrote. When the MBP was connected the voltage instantly ramped up to 16.5V and Magsafe LED was a very dim green (should light up bright green). So I'm pretty sure the chip in the magsafe connector had a fault. Anyway the old PSU is now in the dumpster, after I desoldered all the compoents which maybe useable in a projectGreetings Gregor.

author: German_EE
author_rank: Super Contributor
timestamp: July 27, 2014, 04:24:33 pm
content: An example of the right way and wrong way of doing things:Lenovo Thinkpad W500The charger is 20V 90W and connects using a custom connector which can be found all over the Internet. A single resistor between the center pin and ground indicates if you have a 90W or 65W charger and if you connect the 65W model the laptop reduces the CPU frequency and backlight level to compensate. After market charger? No problem, it's half the price, just make sure that resistor is the right value.Apple Macbook Pro 17"Charger connects using a plug which contains additional electronics and the result of connecting a good cable to a replacement power supply is unknown. If the chip in the connecter fails then a perfectly good power supply will end up in the trash.Please do not misunderstand me, I like Apple, my first computer was an Apple //e and I think that Steve Jobs was a remarkable man, but so long as they continue to pull stunts like this there is no way I will purchase another Apple machine.

author: eas
author_rank: Frequent Contributor
timestamp: September 01, 2014, 06:03:50 pm
content: Chiming in late, but for what it is worth, I've generally had pretty good experience with Apple fixing stuff out of warranty for a reduced rate, or, in the case of things like power bricks, for free.Apple charges a premium for their stuff, and they throw up barriers that frustrate some DIYers, hackers and engineers. This is in part explained by the fact that they aren't just engineering software, or hardware, or a device embodying the two, they are engineering a total user experience that starts before you buy, continues after you buy, and, if they do it right, never ends, because it carries you through repairs, upgrades, etc.Yes, some of the stuff they do, like MagSafe negotiation, is to protect their margins on accessories, but it is also there to keep you within territory that they (usually) take responsibility for.So, its probably too late now that you've torn it apart, but in the future, its worth contacting support, or even better, dropping by an Apple Store.

author: LektroiD
author_rank: Frequent Contributor
timestamp: September 04, 2014, 07:01:46 am
content: Had the same problem, so I bought a cheap replacement from eBay. The noise was awful (I remember this being the same on OEM PC chargers too, no matter how much you spend). If you do anything with audio (even just plugging your mac into your amp to listen to music), replace with original part. In fact, just get the right part anyway. That noise that comes through from PC chargers and fake Apple ones can't be doing the internal components any good.

author: tjb1
author_rank: Regular Contributor
timestamp: September 04, 2014, 12:30:20 pm
content: I had the battery bulge on my 2010 15" MBP this spring, contacted Apple about it and they told me they would do a one time repair on it. I never purchased Applecare for it and it was long out of warranty but they decided to do the repair anyway. They sent me a box with the foam, tape and label all included and I received it the day after I called them. Packed it up, gave it to Fedex on a Tuesday and had the laptop back on Thursday with a brand new battery and logic board.That laptop has been one of the best devices I have ever purchased, besides my hate for the new OS and all the graphical junk (address book and others made to look like real ones) it does well. Once I go through the SSD I will likely toss Snow Leopard back on and enjoy it. Doesn't get used much now because I use many CAD and related programs that work much better on my desktop and being out of college I have no real use for it.That said, I don't understand the Apple hate. My powerbrick lasted nearly 3 years of almost everyday use and cost me $80 to replace with an OEM charger. I don't know why you would screw around hacking a charger up to power such an expensive laptop when the replacement is only $80 and the logic boards are around $700 but I guess that's just me.I guess it's a hip thing to hate Apple?

author: amyk
author_rank: Super Contributor
timestamp: September 04, 2014, 01:13:21 pm
content: Quote from: tjb1 on September 04, 2014, 12:30:20 pmhttps://www.eevblog.com/forum/repair/replacing-apple-magsafe-85w-charger-with-a-normal-laptop-psu-possible/msg486173/#msg486173

author: tjb1
author_rank: Regular Contributor
timestamp: September 04, 2014, 02:04:01 pm
content: Quote from: amyk on September 04, 2014, 01:13:21 pm.What a great and informative reply. If you are too cheap to buy a $80 supply which lasts quite a long time, go pick up a disposable Compaq from Walmart that way you can just buy a new one every year.

author: h1386343
author_rank: Regular Contributor
timestamp: September 04, 2014, 02:07:12 pm
content: Logical steps:#1 Ignore the Apple Ignorant/"haters" - they won't help you.#2 Buy a new magsafe PSU.#3 Carry on with life.It's not even worth a conversation, especially with folk with some irrational anti-Apple agenda.

author: h1386343
author_rank: Regular Contributor
timestamp: September 04, 2014, 02:16:59 pm
content: Quote from: Electr0nicus on July 19, 2014, 07:50:38 amApple design products for the everyman, they don't target the designs towards electronics hobbyists or engineers - these are simple to use consumer products that the world loves. They don't set out with a "mission to thwart repair engineers" - thats ridiculous. They're in the design business, and sell to the public, and considering they're worth over $167 BN, I'd say they've pretty much nailed it.What WOULD be shocking would be if they designed things that fell apart and electrocuted the public. Just because you don't happen to understand the rationale behind their reasons for magsafe and how it works, that doesn't make it "weird and useless", it just makes it something you don't know the purpose of - they're not in the business of making arbitrarily complex designs just for the fun of it.

author: techiesteve
author_rank: Newbie
timestamp: September 13, 2014, 01:54:16 pm
content: I note the OP is based within the EC. It's likely that if he had contacted Apple or an Apple Authorised Service Provider he could have submitted a European Consumer Law Claim for an FOC replacement. Obviously if he had opened up a sealed (for safety) power adapter that option would have been void. He would have needed the original receipt, and as in the claim title, it must have been purchased a consumer, not a business. The repair/replacement would have been under the S/N of the MacBook Pro, and should have been made available with the defective power adapter. He would then have signed and dated a claim form with the technician, who would have scanned the receipt/invoice. When the technician submits the repair within GSX they are prompted wether a claim can be submitted. If older than 2 years it's marked for review by Apple. The last claim I submitted was approved that evening and the replaced part shipped the next day. A lot less hassle.Steve, who works as a technician at an AASP, but previously spent nearly 40 years in component level repair and is an amateur radio full license holder who loves construction and restoration.

author: sunnyhighway
author_rank: Frequent Contributor
timestamp: September 14, 2014, 05:59:16 am
content: Quote from: techiesteve on September 13, 2014, 01:54:16 pmOf-course that would save a lot of hassle it's not mandatory. By ruling, a bankstatement would also be a sufficient proof of purchase.

author: cybertronicify
author_rank: Regular Contributor
timestamp: September 14, 2014, 06:54:41 am
content: Apple will replace the adapter for free if the adapter is frayed.http://support.apple.com/kb/TS4127But if they somehow say they will not replace, then you can replace the adapter with a aftermarket one. The 85w Magsafe has dual voltages with 16.5v at lower power mode and 18.5v at high power mode. They do this to put less strain on the internal components of the MacBook Pro. Which is why you can use the 85w on a 13in MBP. You can safely run the 15 inch ONLY mac on 18.5v (not sure about 17in). In order for the mac to even accept the charge. You need to get a 85w version of the cable because there is a data pin in the 5 pin magsafe connector (- + sense + -) fortunately if your cable is not that damaged you can salvage it from the original charger. I have a Intocircuit PC26000 which gives out 12v 16v and 19v. It has been powering my mac for 1 year now and it is working fine as a secondary battery. Just make sure you get the polarity correct.Inside is Pos and outside is Neg.I have done a few test on the Mid 2012 15in MBP.Max Current: 4.48 A (never goes over this number)Max Voltage: 21 V (stops charging)Watts: 94.08 WWhen running on the 85W adapter it CANNOT charge the battery. But it actually draws a little bit of power from the battery. The way i measure it is with iStat Menus, Intel Power Gadget, and Bench Power Supply.

author: Stonent
author_rank: Super Contributor
timestamp: September 14, 2014, 09:00:48 am
content: The other day I noticed you can buy used MBP's on ebay for about the same price as a replacement motherboard.The Core2Duo MBPs are around $200 now.

author: cybertronicify
author_rank: Regular Contributor
timestamp: September 14, 2014, 01:38:56 pm
content: For the MacbookPro 's (Different from MacBook) The CPU and GPU are BGA types and soldered onto the board. That is why the boards are so expensive. I have a i7-3720qm soldered and that chip itself costs $350, now add in a GT 650m and you got 2 chips soldered to a board that costs nearly $600+

author: FransW
author_rank: Frequent Contributor
timestamp: December 26, 2017, 04:32:05 pm
content: I just modified a 19V 3Amp laptop power supply (switcher) with a cheap Chinese Magsafe 2 connection and my MacBookPro Retina 15" does not have any problem with this power supply.However, it does not charge the batteries as could be expected due to the 1-wire communication protocol and IC absence.So anyone who wants to run his Macbook independant from the batteries can follow this example.Regards, Frans

author: Electro Detective
author_rank: Super Contributor
timestamp: December 29, 2017, 11:12:07 pm
content: FWIW, I have always found the Apple charger cables to vary in quality, and rarely the charger internals at faultunless driven over by a forkliftFinding breaks and or applying heatshrink to reinforce weak spots and the sometimes splitting and fragmenting cable sheathing makes for a working Magsafe charger,that won't be as flexible to handle nor win any beauty contestsbut saves money, petrol and waiting frustrationIf I was to get a new Magsafe charger (unlikely so far due to DIY fixit) I would get a verified original with warranty,some of the knockoffs are iffy in all respects

author: tooki
author_rank: Super Contributor
timestamp: December 31, 2017, 01:10:41 pm
content: Agreed. The power supplies themselves are top-notch, but the “environmentally friendly” PVC-free cords just suck, they’re too stiff, and the insulation eventually gets warped and brittle. (On one MagSafe cord I have, the outer jacket seems to have stretched longitudinally, seemingly several centimeters. Obviously it cracked and has splintered off. Even with heatshrink there’s only so much I can do though!)

author: Electro Detective
author_rank: Super Contributor
timestamp: January 01, 2018, 01:08:15 am
content: I've come across a few of these, and at first suspected cats or dogs chewing/clawing on them and or too much exposure to direct sunlight etc.It soon dawned the cable sheath/covering is literally flimsy, flakey crap, depending on which back alley 'HowLoKanUgO' factory churned it out for Apple Co.,though in their defense I have also come across some that appear identical yet are top notch qualityUsually if the wires are ok, I first I give it a good once over wrap around with good quality white electrical tape that won't goo when heat is applied,then do one continuous (or partial) cover all with either white or clear heatshrink, and offer no apologies for the appearance and stiff handling.They work great, and $5 worth of tape and heatshrink is a better deal IMO than a new chargerwhose internals may be worse than the previous batches...that Apple should HEAVILY discount or offer changeover rates for verified Mac owners who submit their knackered/faulty ones

author: tooki
author_rank: Super Contributor
timestamp: January 02, 2018, 02:19:13 am
content: Obviously Apple isn’t using back-alley factories - making that kind of claim just makes you look stupid. Back-alley factories cannot churn out the volume and adherence to design spec that a company Apple’s size needs.Look at Apple chargers, and the manufacturers are a who’s who of top-tier power supply vendors. But they’re doing them to Apple’s custom specs, and Apple’s specs dictate every detail of their design and suppliers. This includes the PVC-free insulated wire that Apple now uses, having phased out PVC for environmental reasons. But even more than with lead free solder, I wonder if this environmentally friendly insulation isn’t actually resulting in a net negative effect, given the added e-waste due to premature wire failure.

author: tooki
author_rank: Super Contributor
timestamp: January 02, 2018, 02:27:18 am
content: Took me a second to realize what you meant, since you left out “USB”, but yes, that would make total sense. The real proof will be in whether future products also migrate to USB-C or Lightning for charging. Right now most of their laptops still use MagSafe. (And I have to say, I really like MagSafe, it’s prevented so much charging port damage over the years!)Now if only they’d make their USB cords and earphone wire out of wire that doesn’t fail when you look at it wrong...

author: tooki
author_rank: Super Contributor
timestamp: January 02, 2018, 02:39:02 am
content: Nah, that’s not planned obsolescence. (A term that’s frequently, and rather cavalierly, bandied around without understanding what it means.)And I can easily prove that it’s not. How? Because the damned things frequently failwithin the warranty period. Nobody is going to deliberately make things fail when they’re still on the hook to replace them!

author: tooki
author_rank: Super Contributor
timestamp: January 02, 2018, 03:28:05 am
content: Quote from: blueskull on January 02, 2018, 03:17:10 amDon’t be so naive. It’s not just $2. It’s also the logistics costs to get that replacement to you, the wages of the employee who processes it, the overhead for the store to do it in...And for sure, if we are talking a MagSafe charger, which is the original subject of this thread, the cost of the replacement is going to be high enough to not wanna give them away, since they can’t just replace the cord.Also, don’t forget that one of Apple’s biggest markets is Europe, where they must give atwo yearwarranty by law.So yeah, all in all, planned obsolescence simply doesn’t add up here — it doesn’t even pass a rudimentary sanity check. What really boggles my mind is that Apple tolerates the ongoing bad press about the cable quality. Surely that’d make them want to improve it, since it’s incongruent with the high build quality of the devices themselves.

author: Jeroen3
author_rank: Super Contributor
timestamp: January 02, 2018, 08:06:25 am
content: Does anyone have an unbiased test of Apple's silicon cables vs Standard PVC cable?I think both cables fail after similar wear. But one fails on the externally (visibly) and one fails internally.

author: Jeroen3
author_rank: Super Contributor
timestamp: January 02, 2018, 09:45:15 am
content: I have not owned a macbook, but I do have iPhones. I have failed 1 out of 5 cables. The 30-pin variant. Due to it being on my desk and often plugged in and out, and pushed back when not in use. I think this is fair. But I have tossed many more USB B/Mini cables in the bin than I've owned Apple cables.I also have had to re-splice my Dell power cord twice since 2010. I think that's fair as well. The abuse it takes being wound up tightly and put in a backpack more than 200 times a year is quite severe.That's why I ask if anyone did a test instead of just rambling personal biased experiences like I just did.Like this?

author: helius
author_rank: Super Contributor
timestamp: January 02, 2018, 09:49:31 am
content: One aspect that these discussions don't usually cover is that environmentally durable cables are not made in all colors. The UV- and ozone-protective additives that make cables last a long time without cracking are usually based on carbon black. This limits the colors industrial designers can select when durable cables are used; it isn't an accident that SJT flex cables are always black.Like Henry Ford, you can have it in any color you want as long as it's black. Apple's charging cords are notably silver-gray or white.

author: Jeroen3
author_rank: Super Contributor
timestamp: January 02, 2018, 09:56:03 am
content: Now that you mention it. I remember having to throw away my iPod touch earbuds since the cable got all sticky and stuff.

author: tooki
author_rank: Super Contributor
timestamp: January 02, 2018, 04:19:37 pm
content: Quote from: Jeroen3 on January 02, 2018, 08:06:25 amI don’t know of any such comparisons. Somewhat hard anyway, since there aren’t a ton of cables that existed in both variants.FYI, I don’t know what the PVC-free cables are made of, but it’s not silicone. The MagSafe, Lightning, and USB cords use something that goes brittle and splits longitudinally eventually. The earbuds use something very different that’s soft and tacky like silicone. But in both cases, it’s a thermoplastic.Quote from: blueskull on January 02, 2018, 08:59:54 amOh, I’ve definitely had MagSafe cables fail. (Even old ones with PVC insulation.) I have one PVC-free MagSafe with a giant heatshrink section to stop the insulation from fraying. (But of course the fault will eventually reappear at the end of the heatshrink.)There’s tons and tons of reports of MagSafe cable failures, they’re notorious for it. So is failure of Lightning cables, but since they don’t cost anywhere near as much to replace, people don’t make quite as big a fuss about it.

author: tooki
author_rank: Super Contributor
timestamp: January 02, 2018, 04:21:34 pm
content: Quote from: Jeroen3 on January 02, 2018, 09:45:15 amThat said, it’s extremely rare for them to fail mid-cable. That’s not the failure mode we are worried about. Where Apple cables invariably fail is at the strain reliefs.