Exploding Lite-on / Apple SMPS - Page 1
Forum section: electronics / general

author: bd139
author_rank: Super Contributor
timestamp: December 05, 2018, 04:37:00 pm
content: Had my Apple A1424 charger explode last night. Went with a proper bang it did. Spent some time tearing it down today and found this nice hole in the IC.Was expecting it to have been a cap going bang based on the noise but no.MOSFETS + diodes test fine. Any ideas what could cause this catastrophic destruction?

author: wraper
author_rank: Unknown
timestamp: December 05, 2018, 04:58:01 pm
content: Usually IC explodes because of faulty MOSFET hitting it with current through it's gate. In this case it might be that IC is directly powered from rectified mains voltage without need of auxiliary winding as some SMPS controllers do.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 05, 2018, 06:37:39 pm
content: Hit with a surge, maybe?No idea what the chip is, bootstrap gate driver maybe?Not much that'll take out a controller but leave the transistors okay. That said, I've seen at least two supplies where the controller died an idomatic death while everything else was fine.Tim

author: MrMobodies
author_rank: Super Contributor
timestamp: December 05, 2018, 06:55:08 pm
content: There are 222 complaints out of 8 five star ratings about that Apple A1424 charger mostly about overheating and breaking down.https://www.apple.com/uk/shop/reviews/MD506B/B/apple-85w-magsafe-2-power-adapter-for-macbook-pro-with-retina-displayI came across a couple of them when I was replacing some screen parts and hard drives.They were the ones that plug in on the wall and and they were fine and didn't get hot.

author: bd139
author_rank: Super Contributor
timestamp: December 05, 2018, 06:58:06 pm
content: This one ran pretty warm. It was 5 years old so not terrible lifespan.

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 05, 2018, 07:10:47 pm
content: Is the exploded IC reference visible? (It's not on the picture.)

author: 0culus
author_rank: Super Contributor
timestamp: December 06, 2018, 04:45:24 am
content: Wow, that looks very cooked. I have quite a bit of Apple gear, but their chargers and cables really leave a lot to be desired. All of the larger chargers for the 15" (and 17" when it was still made) MBPs I've encountered get super hot when the device is charging.Don't get me started on their zero strain relief cables. I have a (growing) collection of Anker cables of all types that I use instead of the OEM whenever possible, the only exception right now is the USB-C cable for my 12" MacBook and the USB-C-lightning cable I have so I can fast charge my iPhone from that computer's 29W brick.

author: bd139
author_rank: Super Contributor
timestamp: December 06, 2018, 07:55:09 am
content: @kripton: thanks for the schematic. That’s got the same part on as mine. Not going to bother fixing it. Refurb one was only £35.@0culus: Yeah this was running pretty hot. Was used on a 14” model. Had same problem with their cables. Total crap. Usually use Amazon Basics ones now.Bought a MacBook Air to replace the MBP now as well. Figured I don’t want to get rid of this while it’s still worth something. Don’t want to be around for its funeral!

author: amyk
author_rank: Super Contributor
timestamp: December 06, 2018, 12:51:01 pm
content: Why am I not surprised that the schematic is in Russian...This appears to be the only information on that IC in the Internet:http://www.rom.by/files/dap013_858.pdf

author: TimNJ
author_rank: Super Contributor
timestamp: December 07, 2018, 11:00:14 pm
content: My guess is overvoltage transient on Pin 14, the high voltage startup pin. There is no MOV on the input.

author: bd139
author_rank: Super Contributor
timestamp: December 07, 2018, 11:09:02 pm
content: Yeah there is a design flaw there for sure. New one arrived and works. Fortunately it didn’t kill the input board on the laptop. New one runs damn hot as well. Think a little meanwell SMPS adjusted down to 20V would be a better charger. The brains are in the connector end.

author: wraper
author_rank: Unknown
timestamp: December 08, 2018, 02:32:07 am
content: Quote from: bd139 on December 07, 2018, 11:09:02 pmThere is nothing special about it running hot. It's small 85W PSU placed into plastic box without any ventilation. Give or take, you won't make it work cool.

author: kripton2035
author_rank: Super Contributor
timestamp: December 08, 2018, 08:22:53 am
content: Quote from: bd139 on December 06, 2018, 07:55:09 ambeware of dangerous non-apple adapters ...http://www.righto.com/2016/09/why-you-shouldnt-use-cheap-macbook.htmlhttp://www.righto.com/2015/11/macbook-charger-teardown-surprising.html

author: bd139
author_rank: Super Contributor
timestamp: December 08, 2018, 08:32:08 am
content: Yeah aware of that. I bought this from someone I’ve worked with. He recycles old kit bought from corporate disposals. Sells the parts that work on and builds Frankenstein MacBooks when he can. Extremely low chance of hooky kit coming through.

author: wraper
author_rank: Unknown
timestamp: December 08, 2018, 02:18:58 pm
content: Quote from: kripton2035 on December 08, 2018, 08:22:53 amThat one is actually quite good as far as knockoffs go. It's very rare to see decent creepage distance. Decent transformer size. Second is not that bad too. Often you see 1-2 mm of creepage.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: December 08, 2018, 02:34:19 pm
content: Is it me or are the line filter common mode chokes drawn wrong in the schematic? Or are they really like that in the supply?I thought they go this way

author: wraper
author_rank: Unknown
timestamp: December 08, 2018, 02:35:48 pm
content: Quote from: Alex Eisenhut on December 08, 2018, 02:34:19 pmAt least it's completely normal to see 2 common mode chokes in series in PSU. EDIT: although direction of the windings is marked wrong, maybe you mean that.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 08, 2018, 02:56:59 pm
content: I would expect so, yes.Tim

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: December 08, 2018, 03:03:11 pm
content: Quote from: wraper on December 08, 2018, 02:35:48 pmAh, I see what you mean. I meant the phase was wrong, not the amount!